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Constructing nanoscale coordination polymers (CPs) with different micro- or nanoscale morphologies and sizes is crucial for the functionalization of CPs-based heterogeneous catalysts. Herein, surfactant polyvinylpyrrolidone (PVP), surface-supported frameworks (filter paper or Ni foam), and Co-based CPs (1), [Co 2 (pdpa)(py) 4 (H 2 O)] n (H 4 pdpa ​= ​5,5'-(pentane-1,2-diyl)-bis(oxy)diisophthalic; py ​= ​pyridine)) were employed to develop highly ordered micro- or nanoscale CPs, achieving microscale 1a (without surface-supported framework) and nanoscale 1b-c (filter paper and Ni foam as surface-supported frameworks for 1b and 1c , respectively). Furthermore, the catalytic performance of nanoscale 1c with spheric particles for the tandem conversion reactions of aromatic nitriles and diamines into imidazoline or tetrahydropyrimidine frameworks was much more prominent than that of large scale 1 , microscale 1a , and nanoscale 1b because of the easily accessible catalytic active sites in the nanoscale spheric particles, which offered a functionalizable platform for the tandem reactions by minimizing the diffusion distance but did little for their activity. By introducing surfactant and surface-supported frameworks, different morphologies and particle sizes of Co-based CPs with micro- or nanoscale 1a-c were constructed and were used as efficient heterogeneous catalysts to execute tandem conversion reactions. [Display omitted] • A new Co-based CPs was constructed under solvothermal conditions. • Co-based CPs with different morphologies and particle sizes were obtained. • The catalytic performance of all the prepared particles for tandem reactions was conducted. [ABSTRACT FROM AUTHOR]

Countries worldwide consider solid waste collection and recycling necessary due to the recent emphasis on conservation of resources and environmental protection. Due to the constraints from resource depletion and the need for sustainable economic growth, solid waste recycling has become a critical issue in China. Several indigenous researchers in China have studied the potential benefits of solid waste recycling. However, most studies limited the environmental assessment of solid waste recycling to greenhouse gas (GHG) emissions and considered only one type of solid waste (paper or plastic). Therefore, the present study analyzed the energy (electricity) and environmental (GHG and air pollutant emissions) benefits of recycling steel, nonferrous metal, plastic, and paper wastes from 2005 to 2017 in China. The study used the formulation of model equations method to estimate the electrical energy and environmental benefits. Prominent findings show that the total amount of electricity saved by recycling solid waste from 2005 to 2017 was 3743.3 Mtce. On average, solid waste recycling during the period led to a 43.2% saving on electricity. Solid waste recycling avoided 4765.9 billion kg of carbon dioxide emission and 22.502 billion kg of methane emission. It was also found that the recycling of solid waste saved a total amount of 10,669.8 M kg of NO X emission but had a burden of −6263.2 M kg of VOCs emission on the environment. Solid waste recycling avoided the emission of CO 2 , CH 4 , NO X , and SO X, but the recycling of steel, plastics, and paper waste had negative impacts on the environment in terms of VOCs and PM emissions. Proper measures such as installing air pollution control devices should be put in place to minimize the emission of pollutants during the recycling of these solid wastes. • The energy and environmental benefits of solid waste recycling is assessed. • The formulation of model equations method was used for the assessment. • On average, the recycling of solid waste saved 43.2% of electricity. • Recycling of waste avoided a significant amount of GHG and air pollutant emissions. • Solid waste recycling had no essential benefit on the emission of VOCs and PM. [ABSTRACT FROM AUTHOR]

This paper utilized the hydrothermal method and freeze-drying technology to prepare the macroscopic aerogel structure and powder structure of MOF-808/RGO. Through comparative analysis of aspects such as photocatalytic CO 2 reduction performance, electron transfer efficiency, macroscopic structure, and microstructure, it has been discovered that aerogel structure can provide favorable conditions for mass transfer of CO 2 and water molecules, and light propagation. The introduction of RGO successfully captures electrons and the reduction reaction occurs on the surface of the material. [Display omitted] • Macroscopic aerogel and powder structures of the MOF-808/RGO composite photocatalysts were fabricated separately and used for comparison. • The photocatalytic performance of the MOF-808/RGO macroscopic aerogels in reducing CO 2 to CO was approximately 16 times that of MOF-808 and 12 times that of RGO. • The aerogel structure provides an abundance of pore structures within the material. • The presence of the aerogel structure successfully enhanced the photothermal and photoelectric conversion efficiencies of the composite photocatalysts. Three-dimensional (3D) macroscopic aerogels have emerged as a critical component in the realm of photocatalysis. Maximizing the integration of materials can result in enhanced efficiency and selectivity in photocatalytic processes. In this investigation, we fabricated MOF-808/reduced graphene oxide (RGO) 3D macroscopic aerogel composite materials employing the techniques of hydrothermal synthesis and freeze-drying. The results revealed that the macroscopic aerogel material exhibited the highest performance in CO 2 reduction to CO, particularly when the concentration of RGO was maintained at 5 mg mL−1. In addition, we synthesized powder materials of MR-5 composite photocatalysts and conducted a comparative analysis in terms of photocatalytic CO 2 reduction performance and electron transfer efficiency. The results show that the macroscopic aerogel material boasts a high specific surface area, an abundant internal pore structure, and increased active sites. These attributes collectively enhance light energy utilization, and electron transfer rates, thereby, improving photothermal and photoelectric conversion efficiencies. Furthermore, we conducted in-situ FT-IR measurements and found that the M/R-5 aerogel exhibited the best CO 2 adsorption capacity under a CO 2 flow rate of 10 mL min−1. The density functional theory results demonstrate the correlation between the formation pathway of the product and the charge transfer pathway. This study provides useful ideas for realizing photocatalytic CO 2 reduction of macroscopic aerogel materials in gas–solid reaction mode. [ABSTRACT FROM AUTHOR]

[Display omitted] This paper develops a new measurement method to answer the question: How does one measure the interfacial tension of adsorbed droplets? This measurement is based on the placement of a bubble at a water|organic interface. To prove the concept, a bubble was formed by pipetting gas below the water|1,2-dichloroethane interface. Our values agree well with previous reports. We then extended the measurement modality to a more difficult system: quantifying interfacial tension of 1,2-dichloroethane droplets adsorbed onto conductors. Carbon dioxide was generated in the aqueous phase from the electro-oxidation of oxalate. Given carbon dioxide's solubility in 1,2-dichloroethane, it partitions, a bubble nucleates, and the bubble can be seen by microscopy when driving the simultaneous oxidation of tris(bipyridine)ruthenium (II), a molecule that will interact with CO 2 .−. and provide light through electrochemiluminescence. We can quantify the interfacial tension of adsorbed droplets, a measurement very difficult performed with more usual techniques, by tracking the growth of the bubble and quantifying the bubble size at the time the bubble breaks through the aqueous|1,2-dichloroethane interface. We found that the interfacial tension of nanoliter 1,2-dichloroethane droplets adsorbed to an electrified interface in water, which was previously immeasurable with current techniques, was one order of magnitude less than the bulk system. [ABSTRACT FROM AUTHOR]

Insufficient active sites at the hydrophilic grassy CuO electrode tend to produce H 2 in electrochemical CO 2 reduction reaction. To enhance the intrinsic catalytic activity, a metal-oxide heterogeneous interface was created via interfacial engineering modulation by loading Pd on CuO. The CuO/Pd electrode exhibited excellent electrochemical CO 2 reduction performance, with 54% Faraday efficiency at −0.65 V for CH 3 OH. [Display omitted] • The active site of the grass-like hydrophilic CuO electrode was verified to be oxide-derived Cu by the transition in wettability. • Pd loading on CuO by interfacial engineering both satisfies the reduction of CuO to Cu and also contributes to the increase of active sites. • The interfacial effect between CuO and Pd appreciably reduces the work function of CuO to promote CO 2 reduction. • The FE of CH 3 OH reach up to 54 % at −0.65 V over CuO/Pd-2. Copper-based catalysts have been extensively investigated in electrochemical carbon dioxide (CO 2) reduction to promote carbon products generated by requiring multiple electron transfer. However, hydrophilic electrodes are unfavourable for CO 2 mass transfer and preferentially hydrogen (H 2) evolution in electrochemical CO 2 reduction. In this paper, a hydrophilic cupric oxide (CuO) electrode with a grassy morphology was prepared. CuO-derived Cu was confirmed as the active site for electrochemical CO 2 reduction through wettability modulation. To enhance the intrinsic catalytic activity, a metal-oxide heterogeneous interface was created by engineering modulation at the interface, involving the loading of palladium (Pd) on CuO (CuO/Pd). Both the electrochemically active area and the electron transfer rate were enhanced by Pd loading, and significantly the reduced work function further facilitated the electron transfer between the electrode surface and the electrolyte. Consequently, the CuO/Pd electrode exhibited excellent excellent performance in electrochemical CO 2 reduction, achieving a 54 % Faraday efficiency at −0.65 V for methanol (CH 3 OH). The metal-oxide interfacial effect potentially improves the intrinsic catalytic activity of hydrophilic CuO electrodes in electrochemical CO 2 reduction, providing a conducive pathway for optimizing hydrophilic oxide electrodes in this process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co 2 N C with diatomic pair sites was successfully prepared. • Co 2 N C exhibited much faster degradation kinetic rate than Co 1 N C. • More ROS were generated by the catalysis of Co 2 N C. • DFT calculation further revealed the enhanced activity of Co 2 sites. A novel strategy for better catalytic performance in terms of precisely tuning the metal atom number of active centers is gradually getting attention. In this paper, the Co atom pair sites on N -doped porous carbon was engineered. The binuclear Co 2 site structure was identified by aberration-corrected scanning transmission electron microscopy and X-ray absorption spectroscopy. As expected, the Co 2 N C display an outstanding Fenton-like catalysis activity in tetracycline degradation with turnover frequency exceeding 0.91 min−1 that is approximately 4 times higher than the conventional CoN 4 site. The EPR tests indicated that the ROS strength stimulated by the binuclear site was much stronger than that of single site. Theoretical density functional theory calculations reveal that the optimized adsorption configuration is the O1 of peroxymonosulfate (PMS) interacting with two Co atoms, leading to stronger interaction effect and electron transfer for PMS comparing to single atom sites. [ABSTRACT FROM AUTHOR]

[Display omitted] • The adsorption energies of CO 2 on the surface oxygen vacancies of different crystalline In 2 O 3 were calculated using DFT. • The effect of the spatial distributions of two active components on the CO 2 hydrogenation to aromatics was studied. • The acidity of catalyst under different spatial distributions was studied through NH 3 -TPD. In tandem catalysts, not only good synergy between the two active components is required, but also the precise control of the spatial distribution between the two active components of metal oxides and zeolite is crucial for the migration and conversion of reaction intermediates in the direct conversion of CO 2 to hydrocarbons. The correlation between the metal and the acidic site of zeolite has traditionally been simplified as "the closer, the better". However, it should be noted that this principle only holds true for a portion of tandem catalysts. Therefore, this paper studied the effect of different crystalline In 2 O 3 (cubic phase, hexagonal phase, and mixed cubic/hexagonal phase) and sheet HZSM-5 zeolite tandem catalysts on the activity of CO 2 hydrogenation reaction under different spatial distribution. The generalized gradient approximation (GGA) of density functional theory (DFT) were used to simulate the adsorption energy of CO 2 by oxygen vacancy on c-In 2 O 3 (1 1 1) and h-In 2 O 3 (1 0 4) planes, it was found that O v1 on c-In 2 O 3 (1 1 1) and O v4 on h-In 2 O 3 (1 0 4) had the strongest adsorption energy for CO 2. In addition, it has been observed that the proximity of the two active components (e.g., during mortar mixing) results in decreased catalytic performance. This is due to the migration of metal In, which neutralizes the acid sites of zeolites and leads to inefficient conversion of methanol reaction intermediates to aromatics. As a result, CO 2 conversion and aromatic selectivity are decreased. [ABSTRACT FROM AUTHOR]

Designed hexagonal ZnIn 2 S 4 nanosheets wrapped oxygen deficient blue TiO 2 (B) catalyst for highly stable and selective CO 2 Photoreduction into CO and CH 4. The advanced photoactivity is attributed due to improved CO 2 absorption capacity, electron mobility, and visible light accessibility, resulting in effective charge carrier separation and transfer process. [Display omitted] • Simple approaches were used to develop nanocavity assisted oxygen deficient blue TiO 2 (B) nanorods (BT) and ZnIn 2 S 4 nanosheets. • Exfoliating bulk ZnIn2S4 nanosheets into a few layers (ZIS) and integrating them on BT generates a BT/ZIS composite. • The integration of BT on ZIS accelerates charge separation and migration due to high absorption capacity and well-matched band potentials. • The optimized BT/ZIS has a high CO 2 conversion rate into CO and CH 4 , as well as great selectivity and durability. Developing new and highly stable efficient photocatalysts is crucial for achieving high performance and selective photocatalytic CO 2 conversion. In this paper, we designed a one-dimensional oxygen-deficient blue TiO 2 (B) (BT) catalyst for improved electron mobility and visible light accessibility. In addition, hexagonal ZnIn 2 S 4 (ZIS) nanosheets with a low bandgap and great visible light accessibility are employed to produce effective heterostructures with BT. The synthesized materials are tested for photocatalytic conversion of CO 2 into solar fuels (H 2 , CO and CH 4). The optimized composite yields 71.6 and 10.3 μmol g−1h−1 of CO and CH 4 , three and ten times greater than ZIS, respectively. When ZIS nanosheets are combined with a one-dimensional oxygen-deficient BT catalyst, improved electron mobility and visible light accessibility are achieved, charge carriers are effectively segregated, and the transfer process is accelerated, resulting in efficient CO 2 reduction. The photocatalytic CO 2 conversion activity of the constructed BT/ZIS heterostructures is very stable over a 10-day (240-hour) period, and CO and CH 4 production rates increase linearly with time; however, as time goes on, the rates of H 2 production decrease. Further, a five-time recycling test confirmed this, revealing essentially equal activity and selectivity throughout the experiment. As a result, CO 2 to CO and CH 4 conversion has high selectivity and longer durability. The band structure of the BT/ZIS composite is determined using Mott-Schottky measurement, diffuse reflectance spectroscopy, and valence band X-ray photoelectron spectroscopy. This research demonstrates a novel approach to investigating effective, stable, and selective photocatalytic CO 2 reduction systems for solar-to-chemical energy conversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Zn-In-O catalyst exhibits FE HCOO− (94.25 %) at −1.16 V RHE. • Rich interface effects improve the catalytic performance of Zn-In-O. • In 2 O 3 active center of Zn-In-O is protected from reducing by sacrificing ZnO phase. Electrochemical CO 2 reduction reaction (eCO 2 RR) is considered an efficient approach to produce value-added chemicals and fuels. In this paper, a series of MOF-derived composite catalysts with coexisting In 2 O 3 and ZnO are fabricated using a simple process for eCO 2 RR to produce formate. The Zn-In-O/800 catalyst achieves a formate Faradaic efficiency (FE HCOO−) of 94.25 % at −1.16 V vs. RHE, which can maintain over 89 % after 30 h in a stability test. The electrochemical evidence and density functional theory analysis show that the strong interface effect between In 2 O 3 and ZnO can enhance the CO 2 adsorption and activation, and promote the conversion of CO 2 to formate. In addition, the ZnO phase can protect In 2 O 3 , as the main active site, from being reduced to a certain extent for a long time under negative potential, which ensures the high stability of the composite catalyst. [ABSTRACT FROM AUTHOR]

• Ag-Zn bimetal for CO 2 reduction to CO was prepared by the galvanic replacement. • PPy suppressed hydrogen evolution and enabled metals to be deposited on electrodes. • Atomically mixed Ag-Zn improved the CO 2 reduction activity over each single metal. An important strategy for reducing the impact of global CO 2 emissions involves conversion technologies that transform CO 2 into value-added materials. Bimetallic electrocatalysts of Zn and Ag were constructed on polypyrrole-decorated carbon paper (CP/PPy) electrodes for the improved electrochemical reduction of CO 2 to CO. Bimetallic catalysts with different Zn and Ag atomic ratios were produced by the partial galvanic replacement of Zn with Ag on a CP/PPy/Zn electrode. Selectivity for the electrochemical reduction of CO 2 to CO at the CP/PPy/Zn/Ag was clearly improved compared to those of the single-metal catalysts (CP/PPy(Ag or Zn)), while the hydrogen evolution reaction (HER) was suppressed. The PPy interlayer between the catalyst and CP support reduced the hydrophobicity of the carbon paper electrode, which facilitated the effective electrodeposition of Ag and Zn on the CP and suppressed the HER at the electrode. Herein, we propose Zn:Ag bimetallic composites deposited on PPy surfaces as CO-selective electrocatalysts with the optimal Zn:Ag catalyst composition suggested by electrochemical and physicochemical analyses. We experimentally confirmed that the atomically mixed Ag-Zn in the bimetallic catalysts enhanced the CO selectivity and production rate over each single metal catalyst. The developed electrocatalyst resulted in a maximum Faradaic efficiency of approximately 70% and a maximum current density of 8.6 mA/cm2 for the CO 2 reduction reaction to CO in a 1 M KHCO 3 aqueous solution. [ABSTRACT FROM AUTHOR]

[Display omitted] Photocatalytic reduction of CO 2 to high-energy products is an effective way to utilize solar energy and mitigate the greenhouse effect. In this paper, a series of CQDs/Bi 12 O 17 Cl 2 /NiAl-LDH (C/BOC/LDH) photocatalysts were prepared via a one-pot hydrothermal method, demonstrated excellent photocatalytic CO 2 reduction performance. In the case of only water without any photosensitizer and sacrificial agent, the CO production rate on C/0.3BOC/LDH reached 16.4 μmol·g-1h−1, which is 6.7 times higher than that of the original LDH. The construction of Z-scheme heterojunctions inhibited the recombination of electrons with holes. The unique up-conversion PL behavior of CQDs benefitted the absorption of energy in the NIR by the photocatalyst. This study provides meaningful assistance for the design and construction of a ternary photocatalytic system with Z-scheme heterojunction and carbon-based co-catalyst. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO 2) emissions constitute the primary contribution to global climate change. Synthetic CO 2 fixation represents an exceptionally appealing and sustainable method for carbon neutralization. Unlike the limitations of chemical catalysis, biological CO 2 fixation displays high selectivity and the ability to operate under mild conditions. The superfamily of amidohydrolases has demonstrated the ability to synthesize a range of aromatic monocarboxylic acids. However, there is a scarcity of reported carboxylases capable of synthesizing aromatic dicarboxylic acids. Among these, 4-hydroxyisophthalic acid holds significant potential for applications across various fields, yet no enzyme has been reported for its synthesis. In this study, we developed for the first time that exhibits starting activity in fixing CO 2 to synthesize 4-hydroxyisophthalic acid. Furthermore, we have devised a computational strategy that effectively enhances the catalytic activity of this enzyme. A focused library comprising only 13 variants was generated. Experimental validation confirmed a threefold improvement in the carboxylation activity of the optimal variant (L47M). The computational enzyme design strategy proposed in this paper demonstrates broad applicability in developing carboxylases for synthesizing other aromatic dicarboxylic acids. This lays the groundwork for leveraging biocatalysis in industrial synthesis for CO 2 fixation. • Demonstration that carboxylase can synthesize aromatic dicarboxylic acid by fixing CO 2. • 5-Carboxyvanillate carboxylase was found to catalyze the synthesis of 4-HIPA. • Develop an enzyme design strategy combing energy optimization and MD simulation. • The designed variant exhibited a 3-fold increase in carboxylation activity. [ABSTRACT FROM AUTHOR]

In this paper, we propose a multi-RREH (Remote Renewable Energy Hub) based optimization framework. This framework allows a valorization of CO 2 using carbon capture technologies. This valorization is grounded on the idea that CO 2 gathered from the atmosphere or post combustion can be combined with hydrogen to produce synthetic methane. The hydrogen is obtained from water electrolysis using renewable energy. Such renewable energy is generated in RREH, which are locations where RE is cheap and abundant (e.g., solar PV in the Sahara Desert, or wind in Greenland). We instantiate our framework on a case study focusing on Belgium and 2 RREH, and we conduct a techno-economic analysis under uncertainty. This analysis highlights, among others, the interest in capturing CO 2 via Post Combustion Carbon Capture (PCCC) rather than only through Direct Air Capture (DAC) for methane synthesis in RREH. By doing so, a notable reduction of 10% is observed in the total cost of the system under our reference scenario. In addition, we use our framework to derive a carbon price threshold above which carbon capture technologies may start playing a pivotal role in the decarbonation process of our industries. • We demonstrate PCCC technology potential for reducing RREH's CH4 production cost. • We derive a carbon price threshold for crucial industrial decarbonization. • An uncertainty analysis has been carried out on the reference scenario. [ABSTRACT FROM AUTHOR]

Exploring whether informal environmental regulations (INER) can achieve carbon reduction in the context of pollution reduction and carbon reduction, as well as how to achieve carbon reduction, can help solve the dual failures of the market and government in environmental protection. Based on the polycentric governance theory and considering the characteristics of social subject environmental participation, the Stackelberg game is used to demonstrate the impact mechanism of INER on CO 2. In addition, using the panel data of China's 30 provinces from 2003 to 2018, this paper validates the effectiveness of INER by Pooled Ordinary Least Square (POLS) and threshold panel model. Then, the mediating effect model is used to test the mechanism of INER's effect on carbon reduction. The results show that corruption is not conducive to CO 2 reduction. The reduction effect of INER on CO 2 exhibits heterogeneity with changes in other non-greenhouse gas pollutants. While INER effectively reduces local corruption, its more substantial indirect impact on CO 2 reduction is prominent when levels of other pollutants are lower. Comparative analysis reveals that there are still biased governance behaviors to cope with INER's pressure in some regions nowadays. The findings show that for countries facing the dual task of pollution control and carbon reduction, the key to leveraging the supervisory role of INER should be focused on mitigating information asymmetry caused by the characteristics of CO 2. Therefore, in the process of environmental protection, the public environmental participation system should be improved, and the process of disclosing polluters' carbon information should be accelerated. • Polluters may adopt strategic carbon reduction behaviors. • Other pollutants influence the impact of INER on CO 2. • When other pollutants are low, INER significantly reduce CO 2 by constraining corruption. • Some regions still have biased governance behaviors to cope with INER's pressure. [ABSTRACT FROM AUTHOR]

The present paper compared, through life cycle assessment (LCA), the production of aviation biofuel from two hydrothermal routes of microalgae cultivated in wastewater. Hydrothermal liquefaction (HTL) and gasification followed by Fischer-Tropsch synthesis (G + FT) were compared. Both routes included biomass production, hydrotreatment for biofuel upgrading, and product fractionation. Secondary data obtained from the literature were used for the cradle-to-gate LCA. G + FT had a higher impact than HTL in the 18 impact categories assessed, with human carcinogenic toxicity exerting the most harmful pressure on the environment. The catalysts were the inputs that caused the most adverse emissions. The solvent used for bio-oil separation also stood out in terms of impacts. In HTL, emissions for global warming were −51.6 g CO 2 eq/MJ, while in G + FT, they were 250 g CO 2 eq/MJ. At the Endpoint level, HTL resulted in benefits to human health and ecosystems, while G + FT caused environmental damage in these two categories, as well as in the resources category. In the improvement scenarios, besides considering solid, aqueous, and gaseous products as co-products rather than just as waste/emissions, a 20% reduction in catalyst consumption and 90% recovery were applied. Thus, in HTL, 39.47 kg CO 2 eq was avoided, compared to 35.44 kg CO 2 eq in the base scenario. In G + FT, emissions decreased from 147.55 kg CO 2 eq to the capture of 8.60 kg CO 2 eq. [Display omitted] • Gasification + Fischer-Tropsch caused more impacts than liquefaction. • The environment has suffered more harmful pressure on human carcinogenic toxicity. • The catalysts used were the inputs that most caused adverse emissions. • Liquefaction route captured 39.47 kg CO 2 eq with improvement scenario. • Gasification + Fischer-Tropsch captured 8.6 kg CO 2 eq with the improvement scenario. [ABSTRACT FROM AUTHOR]

[Display omitted] • SrTiO 3-x nanosheets were synthesized by simple hydrothermal method; • Sr atom on the SrTiO 3-x surface is the active site of CO 2 adsorption and activation; • COO– and COOH are important intermediates in photocatalytic CO 2 reduction; Converting CO 2 into chemical energy by using solar energy is an environmental strategy to achieve carbon neutrality. In this paper, two dimensionality (2D) SrTiO 3-x nanosheets with oxygen vacancies were synthesized successfully. Oxygen vacancies will generate defect levels in the band structure of SrTiO 3-x. So, SrTiO 3-x nanosheets have good photocatalytic CO 2 reduction performance under visible light. In order to further improve its photocatalytic efficiency, Bi was used to dope Sr site and Ti site in SrTiO 3-x nanosheets respectively. It is found that Sr site is the adsorption site of CO 2 molecules. When Bi replaced Sr, CO 2 adsorption on the surface of SrTiO 3-x nanosheets was weakened. When Bi replaced Ti, there has no effect on CO 2 adsorption. Due to the synergistic effect of Bi doping, oxygen vacancies, and Sr active site, the 1.0% Bi-doped Ti site in SrTiO 3-x (1.0% Bi-Ti-STO) had the best photocatalytic performance under visible light (λ ≥ 420 nm). CO and CH 4 yields were 5.58 umol/g/h and 0.36 umol/g/h. Photocatalytic CO 2 reduction path has always been the focus of exploration. The in-situ FTIR spectrum proved the step of photocatalytic CO 2 reduction and COO– and COOH are important intermediates in the photocatalytic CO 2 reaction. [ABSTRACT FROM AUTHOR]

Carbon dioxide capture from flue gas (CO 2 /N 2) and natural gas (CO 2 /CH 4) is a challenging and cost-effective task. In this paper, ultramicroporous metal-organic frameworks (MOFs) (Co-norf and Ni-norf) are synthesized to realize the efficient separation of CO 2 /N 2 and CO 2 /CH 4 by metal ion regulation. The Ideal Adsorption Solution Theory (IAST) was calculated to evaluate the adsorption selectivity of activated Co-norf and Ni-norf for CO 2 /N 2 (v/v = 15/85) mixtures and CO 2 /CH 4 mixtures. The CO 2 /N 2 selectivity of Co-norf and Ni-norf at 100 kPa was 734 and 96, respectively, which corresponds to an almost 7.6-fold increase by metal ion modulation. The specific binding sites of CO 2 molecules within the pore channels were obtained by grand canonical Monte Carlo simulation (GCMC). Dynamic breakthrough experiments respond to the actual separation in systems simulating flue gas and natural gas, where the higher saturation adsorption and longer retention time proved that Co-norf is an ideal material for CO 2 capture and separation. The present work provides a feasible approach for the application of MOF in gas separation. The regulation of metal ions on MOF channels is proved through single-component gas adsorption experiment, IAST selective calculation and dynamic breakthrough, which provides an effective way for the application of MOF materials in the field of gas separation. [Display omitted] • The successful synthesis of Co-norf and Ni-norf MOFs with ultramicroporous structures. • Enhanced CO 2 /N 2 and CO 2 /CH 4 selectivities achieved through metal ion regulation. • Co-norf demonstrated high separation performance for CO 2 /N 2 captures. [ABSTRACT FROM AUTHOR]

Rapid economic growth and human activities have seriously damaged the environment and hindered the achievement of Sustainable Development Goals (SDGs). Hence, this study aims to explore the impact of economic complexity, uncertainty, and remittance on environmental degradation in 134 countries from 2000 to 2022. In addition, it examines whether uncertainty moderates the relationship between remittance and environmental degradation. Two proxies (ecological footprint and CO 2) were used to measure environmental degradation. The analysis was conducted using a cross-sectional dependency test, second-generation unit root test, and panel quantile regression. The results revealed that economic complexity significantly and positively impacted environmental degradation, while uncertainty and remittance significantly and negatively impacted environmental degradation. Furthermore, uncertainty weakened the negative relationship between remittance and environmental degradation. Accordingly, this paper discusses various recommendations and policy implications regarding economic complexity, uncertainty, remittance, and environmental degradation. • We examined the impact of economic complexity, uncertainty, and remittance on environmental degradation in 134 countries. • Ecological footprint and CO 2 were used to measure environmental degradation. • Economic complexity significantly and positively impacted environmental degradation. • Uncertainty and remittance significantly and negatively impacted environmental degradation. [ABSTRACT FROM AUTHOR]

Livestock is one of major sources of greenhouse gas (GHG) emissions in China. Clarifying spatiotemporal characteristics of GHG emissions from livestock and exploring influencing factors can provide reference for grasping regional changes of GHG emission and formulate strategies of carbon reduction for livestock industry. However, existing literatures considered both spatial and temporal impacts and dynamic evolution trend of these factors seldomly. This paper used the life cycle assessment (LCA) method to estimate GHG emissions of livestock in 114 cities of the YRB from 2000 to 2021. On this basis, spatiotemporal heterogeneity of influencing factors was analyzed by using geographically and temporally weighted regression (GTWR) model. Finally, future evolution trend of GHG emissions from livestock was predicted by combining traditional and spatial Markov chain. Four main results were listed as follows. Firstly, GHG emission in the life cycle of livestock industry increased from 57.202 million tons (Mt) carbon dioxide equivalent (CO 2 e) in 2000 to 77.568 Mt CO 2 e in 2021. Secondly, structure of livestock industry, labor flow and mechanization were vital factors that led to increase of GHG emissions from livestock. Positive effects of labor flow and mechanization were increasing year by year, while negative effect of urbanization and positive effect of economic development were decreasing year by year. Markov chain analysis shown that probability of keeping high level of GHG emissions of livestock in the YRB unchanged were 96% (T = 1) and 90% (T = 5), and there also existed a Matthew effect. In addition, probability of level transfer of GHG emission in urban livestock was spatially dependent. Government should formulate strategies for livestock development and optimize low-carbon transformation of energy structure for livestock and poultry husbandry based on local conditions and key driving factors in the future. Meanwhile, boundaries of administrative divisions should be broken to promote reduction of GHG emissions in livestock comprehensively. • GHG emissions from livestock in cities of the YRB continued to rise from 2000 to 2021. • GHG emissions per unit of GDP of livestock shown a downward trend. • Analyzing parameter of factors from spatiotemporal aspect by using GTWR model. • Probability of GHG emission transfer in urban livestock was spatially dependent. [ABSTRACT FROM AUTHOR]

Onsite sanitation systems (OSS) are significant sources of greenhouse gases (GHG) including carbon dioxide (CO 2), methane (CH 4) and nitrous oxide (N 2 O). While a handful of studies have been conducted on GHG emissions from OSS, systematic evaluation of literature on this subject is limited. Our systematic review and meta-analysis provides state-of-the- art information on GHG emissions from OSS and identifies novel areas for investigation. The paper analyzes GHG emission rates from different OSS, the influence of various design, operational, and environmental factors on emission rates and proffers mitigation measures. Following the Preferred Reporting Items for Systematic reviews and Meta-analysis (PRISMA) guidelines, we identified 16 articles which quantified GHG emissions from OSS. Septic tanks emit substantial amounts of CO 2 and CH 4 ranging from 1.74 to 398.30 g CO 2 /cap/day and 0.06–110.13 g CH 4 /cap/day, respectively, but have low N 2 O emissions (0.01–0.06 g N₂O/cap/day). CH 4 emissions from pit latrines range from 0.77 to 20.30 g CH 4 /cap/day N 2 O emissions range from 0.76 to 1.20 gN 2 O/cap/day. We observed statistically significant correlations (p < 0.05) between temperature, biochemical oxygen demand, chemical oxygen demand, dissolved oxygen, storage period, and GHG emissions from OSS. However, no significant correlation (p > 0.05) was observed between soil volumetric water content and CO 2 emissions. CH 4 emissions (expressed as CO 2 equivalents) from OSS estimated following Intergovernmental Panel for Climate Change (IPCC) guidelines were found to be seven times lower (90.99 g CO 2 e/cap/day) than in-situ field emission measurements (704.7 g CO 2 e/cap/day), implying that relying solely on IPCC guidelines may lead to underestimation of GHG emission from OSS. Our findings underscore the importance of considering local contexts and environmental factors when estimating GHG emissions from OSS. Plausible mitigation measures for GHG emissions from OSS include converting waste to biogas in anaerobic systems (e.g. biogas), applying biochar, and implementing mitigation policies that equally address inequalities in sanitation service access. Future research on GHG from OSS should focus on in-situ measurements of GHGs from pit latrines and other common OSS in developing countries, understanding the fate and transport of dissolved organics like CH 4 in OSS effluents and impacts of microbial communities in OSS on GHG emissions. Addressing these gaps will enable more holistic and effective management of GHG emissions from OSS. [Display omitted] • Onsite sanitation systems (OSS) are major sources of greenhouse gas (GHG) emission in the environment • Emissions from septic systems vary between 1.74 and 398.30 g/cap/day for CO 2 , and 0.06 and 110.13 g/cap/day for CH 4. • CH 4 emissions from OSS estimated following IPCC guidelines are seven times lower than field-measured emissions. • Local contexts and environmental factors should be considered when assessing GHG emissions from OSS. • Future GHG research on OSS should prioritize in-situ measurements of pit latrines and other OSS in developing nations. [ABSTRACT FROM AUTHOR]

The persistent combustion of fossil fuels has resulted in a widespread greenhouse effect attributable to the continual elevation of carbon dioxide (CO 2) levels in the atmosphere. Recent research indicates that utilizing CO 2 as a pyrolysis gasification medium diminishes CO 2 emissions and concurrently augments the value of the resultant pyrolysis gasification products. This paper reviews recent advancements in the pyrolysis gasification of organic solid wastes under a CO 2 atmosphere. Meanwhile, the mechanisms of CO 2 influence in the pyrolysis and gasification processes were also discussed. In comparison to noble gases, CO 2 exhibits reactivity with char at≥710 °C, resulting in additional mass loss of the sample. In addition, CO 2 was able to increase the specific surface area and stability of biochar and reduce biooil toxicity by lowering the content of cyclic compounds in the biooil, while CO 2 was able to react with GPRs with some volatile products (e.g., light hydrocarbons) to increase biogas yield. Finally, CO 2 also prevents catalyst deactivation by reducing secondary coke formation. We also recommend directing future attention toward utilizing unpurified CO 2 in pyrolysis and gasification. This review aims to expand the utilization of CO 2 and advocate for applying pyrolysis gasification products. [Display omitted] • An overview of recent studies on pyrolysis gasification in CO 2 atmosphere. • The effect of CO 2 on the pyrolysis behavior as well as on the catalyst is illustrated. • The mechanism of the effect of CO 2 on pyrolysis products is described in detail. • In the future, CO 2 and waste heat from industrial flue gases should be utilized directly. [ABSTRACT FROM AUTHOR]

Fits to a solar occultation spectrum measured at 21.7 km tangent altitude from balloon above Esrange, Sweden in Dec. 1999 (Black points). The residual trace represents the difference of the measured and calculated transmittances. Colored lines represent the contributions of individual gases (Red: HNO 3 ; Yellow: CO 2 ; Green: H 2 O; Blue: Other). The HITRAN 2020 line list was used to represent the non-HNO 3 absorptions -- mainly CO 2 and H 2 O. For the HNO 3 line list we used: (a) HITRAN (i.e., none), (b) ExoMol computed for 220K, (c) the JPL empirical pseudo-line-list, and (d) the HNO 3 line list from this work. Each panel shows improved spectral fits compared with the previous panel, from 8.84% RMS in panel (a) to 1.77% RMS in panel (d). [Display omitted] • Validation of the linelist generated for HNO 3 at 2.8 μm (ν 1 cold band at 3551.7 cm−1 and the hot band) and at 3.2 μm (ν 1 -ν 9), 2.5 μm (ν 1 + ν 9) and 2.4 μm (ν 1 + ν 7); Comparison with the Pacific National Northwest Laboratory cross sections for HNO 3 ; Comparison with high resolution spectra recorded in laboratory conditions (SOLEIL synchrotron); Comparison with high resolution stratospheric solar occultation spectra recorded by the MkIV balloon-borne instrument of the Jet Propulsion Laboratory (JPL); Similar inter-comparisons performed using the pseudo-line list generated by the JPL laboratory and the ab initio ExoMol list calculated by the University College of London. This is the second of two back-to-back works, whose goal is to generate line lists for the ν 1 band (3551.766 cm−1) and for the ν 1 +ν 9 -ν 9 and ν 1 +ν 7 -ν 7 hot bands for HNO 3 in the 2.8 μm region. Also, we computed line lists for the weaker ν 1 -ν 9 , ν 1 +ν 9 , and ν 1 +ν 7 bands, centered at 3093.53 cm−1, 4006.97 cm−1 and 4127.78 cm−1, respectively. While the first paper (Ref. [1] , the preceding article in this issue), here labeled as "Part-1", was devoted to the description of the determination of the needed spectroscopic parameters in term of line positions and intensities, this paper describes the resulting line lists and the validation process. For this task, we use laboratory spectra recorded at high resolution and described in Part-1, together with the cross-sections established by the Pacific Northwest Laboratory at low resolution. Also, we use high resolution stratospheric solar occultation spectra recorded by the MkIV balloon-borne instrument of the NASA Jet Propulsion Laboratory (JPL). Similar inter-comparisons with laboratory or atmospheric spectra are also performed using the pseudo-line-list generated at JPL in 2005 and with the ab initio ExoMol list calculated by the University College of London. It proves that the line list generated during this work provides significant better agreements between observed and computed spectra. [ABSTRACT FROM AUTHOR]

This paper reports the usage ratio of TEOS and Zr(OBu) 4 on the formation of Ni@ZrO 2 yolk-shell for dry reforming of methane. From XPS analysis, the ZrO 2 hollow shell texture is demonstrated to be [TEOS]/[Zr(OBu) 4 ] dependent due to different sizes of SiO 2 produced. It found that an adequate ratio of [TEOS]/[Zr(OBu) 4 ] improves the catalytic conversion of dry reforming of methane. It (Ni@ZrO 2 -SiZr-7.7) shows 90% conversion for CH 4 and 93% for CO 2 at a WHSV of 72,000 mLg cat −1h−1 for 50 h at 800 °C with TOF CH4 of 8.7 s−1. It proposed that the changes in surface Si/Zr and gradual interconnecting pores contributed to its activity and stability. These finding's potential to be utilized in other high-temperature reactions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Atomically dispersed Ru/Mg-CeO 2 catalyst was prepared and possessed excellent catalytic performance for photo-thermal catalytic CO 2 methanation reaction. • The photo-electron excitation/migration path and the surface structure changes induced by light were systematically characterized by operando experiments. • All potential micro-reaction steps and light intensification steps were determined by in situ DRIFTs experiments. • The reversible dynamic structural evolution between Ru-O-Ce structure and Ru-O v -Ce structure could be induced by light. It is a promising green technology to reduce CO 2 to CH 4 by using renewable solar energy driving photo-thermal catalysis route. However, the efficiency of photo-thermal catalytic CO2 methanation remained to be improved, and the mechanism of this reaction still required further investigation. In this paper, a Ru/Mg-CeO 2 catalyst was designed based on the concepts of single atom catalyst and photo-thermal catalysis concept. The catalyst achieved the CH 4 formation rate of 469 mmol·gcat−1·h−1 at 400 °C under photo-thermal conditions with good catalytic stability. Besides, the superiority of the single-atom of Ru, Ru-O-Ce structure and doping of alkaline metals in catalytic process was proved by a series of physicochemical and optical characterization, and electron migration direction from Ce and Mg elements to Ru sites through Ru-O-Ce and Ru-O-Mg path under photo-thermal catalysis was determined by ISI-XPS experiment. Finally, the comprehensive reaction mechanism and reversible dynamic structural evolution process between Ru-O-Ce and Ru-O v -Ce structures were investigated by in situ DRIFTs experiments, and the source of the excellent performance and structure-function relationship of the catalyst was explored, which provided the theoretical and practical basis for the development of catalyst and industrial application of the reaction. [ABSTRACT FROM AUTHOR]

By introducing functional groups into the isophthalate ligand to decorate the pore of the MOFs, gas adsorption and separation performance can be tunable. In this paper, two isostructural 2D Co-MOFs, [Co(5-MIA)(bpy)]·H 2 O (1) and [Co(5-EIA)(bpy)]·H 2 O (2) (5-H 2 MIA = 5-methoxyl-isophthalic acid; 5-H 2 EIA = 5-ethyoxyl-isophthalic acid; bpy = 4,4′-bipyridine), with different functionalized pore surfaces and channel sizes were designed and constructed. The structures and performance of the two Co-MOFs were analyzed by SCXRD, PXRD, IR, TGA, and gas sorption (CO 2 , C 2 H 2 , CH 4 , CO, and N 2). Attributed to the methoxyl of isophthalate skeleton, 1a (activated 1) shows enhanced CO 2 uptake over other gases. In spite of decreased pore sizes (3.49 Å) compared with 2a (4.38 Å), the CO 2 uptake of 1a (43.41 cm3 g−1) is larger than that of 2a (22.39 cm3 g−1) at 298 K and 100 kPa. Compound 1 incorporates methoxyl groups into the narrow channel, and exhibits the cooperative effect of CO 2 -preferential due to adsorbent-adsorbate coactions and size sieving. GCMC simulation has been used to explore the adsorption coactions of CO 2 and 1 , and the results confirmed that the methoxyl groups in the channel are the main binding sites of CO 2. At ambient temperature and 100 kPa, the IAST selectivities of CO 2 /C 2 H 2 (1:1), CO 2 /CH 4 (1:1), C 2 H 2 /CH 4 (1:1), CO 2 /CO (1:2) and CO 2 /N 2 (15:85) on 1a were 2.6, 39.3, 13.3, 282 and 1433, respectively. The easy activation and regeneration, excellent thermal and humidity stability, and good reusability, make 1 a hopeful adsorbent for adsorption and separation of CO 2. By introducing functional groups into the isophthalate ligand to decorate the pore of the MOFs, gas adsorption and separation performance can be tunable. Two isostructural 2D Co-MOFs with different functionalized pore surfaces and channel sizes were constructed and show different C 2 H 2 /CH 4 and C 2 H 2 /CO 2 gas separation properties. [Display omitted] • Title compound represent the first example of 3D MOF based on 5-H 2 MIA and bpy. • 1a (activated 1) shows enhanced CO 2 uptake over C 2 H 2 , CH 4 , CO and N 2. • 1a shows an excellent reuse performance. [ABSTRACT FROM AUTHOR]

This paper analyses the impact of geopolitical risk on carbon dioxide (CO 2) emissions inequality in the panel dataset of 38 developed and developing economies from 1990 to 2019. At this juncture, the empirical models control for the effects of globalisation, capital-labour ratio, and per capita income on CO 2 emissions inequality. The panel cointegration tests show a significant long-run relationship among the related variables in the empirical models. The panel data regression estimations indicate that geopolitical risk, capital-labour ratio, and per capita income increase CO 2 emissions inequality. However, globalisation negatively affects CO 2 emissions inequality in the panel dataset of 38 developed and developing countries. The pairwise panel heterogeneous causality test results align with these benchmark results and indicate no reverse causality issue. Potential policy implications are also discussed. • Geopolitical risk, capital-labour ratio, and income increase CO 2 emissions inequality. • Globalisation negatively affects CO 2 emissions inequality. • Long-run relationship exists among Geopolitical risk, capital-labour ratio, income, and CO 2 emissions inequality. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study on polyhydroxyalkanoate (PHA) production from sewage sludge. Greenhouse gas (GHG) emissions were monitored for the first time to assess the impact of climate change and environmental sustainability. The pilot plant was composed of a fermenter with a membrane and two biological reactors (namely, selection and accumulation). Results showed that despite a low organic loading rate (namely, 0.06 kg BOD kg SS−1 day−1), a good PHA yield was obtained (namely, 0.37 g PHA/g volatile fatty acids), confirming that sewage sludge can be a suitable feedstock. GHG emissions were 3.85E-04 g CO 2 eq/g and 32.40 g CO 2 eq/g, direct and indirect, respectively. Results provided valuable insights in view of finding a trade-off between PHA production and GHG emissions to prove the PHA production process as an effective solution for biosolids disposal at a low carbon footprint. [Display omitted] • Sewage sludge acidogenic fermentation at low carbon footprint was performed. • High COD, ammonia and phosphate removal was achieved. • Final PHA concentration of 0.37 g PHA/g VSS was obtained. • N 2 O emission factor accounted for less than 1 % of total nitrogen. • N 2 O direct and indirect emissions were 3.85E-04 and 32.40 g CO2eq/g treated sludge. [ABSTRACT FROM AUTHOR]

One of the most important challenges in the fabrication of Cu x O microstructures via the electrochemical method is formation of long, regular and well-packed microwires with good adhesion on the Cu substrate and to achieve better photoelectrochemical properties, which can be potentially applied in solar-driven water splitting and CO 2 conversion to light hydrocarbons. In this paper, Cu 2 O photoelectrode has been fabricated by direct anodization of the Cu foil, then CuO microwires (MWs) was formed by calcination process. The effect of the applied potential (10–40 V), sodium fluoride content in the electrolyte (0.2–0.5% wt.) as well as calcination conditions (400–500 °C, 60–360 min) on the morphology, phase composition, optical and photoelectrochemical properties was investigated. The highest photocurrent response was −0.71 mA cm−2 for the sample 0.35%_10V_400 °C_60min with 0.83 μm length and 154 nm diameter. The mechanism of the photocurrent generation process in the presence of Cu x O/Cu under UV–Vis irradiation was proposed. Thin films of CuO MWs/Cu 2 O were produced on the surface of Cu plates by anodic oxidation. A tendency of increase in the number and length of microwires was observed with the increase in NaF concentration and the increase in the voltage applied during anodization. A mechanism for the synthesis and photoexcitation of the obtained samples was also proposed. [Display omitted] • Optimization of the Cu anodization - voltage (10–40 V); NaF conc. (0.2–0.5% wt.); calcination (400–500 °C, 60–360 min). • Tendency to increase the length and number and decreasing diameter of the microwires with increasing NaF conc. and voltage. • Increasing the photocurrent response 1.65 timer comparing to calcinated pristine Cu plate. • Proposed mechanism of the photocurrent generation process in the presence of Cu x O/Cu under the UV–Vis irradiation. [ABSTRACT FROM AUTHOR]

• Pre-electrolysis imaging in IL-SEM can locally inactivate the catalyst surface. • Passivation occurs due to the under-beam formation of a carbonaceous crust. • The carbonaceous crust is formed by the irradiation of capping agent remnants. • Different degradation patterns are observed on pre-scanned and pristine areas. Identical location scanning electron microscopy (IL–SEM) has become an important tool for electrocatalysis research in the past few years. The method allows for the observation of the same site of an electrode, often down to the same nanoparticle, before and after electrochemical treatment. It is presumed that by IL–SEM, alterations in the surface morphology (the growth, shrinkage, or the disappearance of nanosized features) can be detected, and the thus visualized degradation can be linked to changes of the catalytic performance, observed during prolonged electrolyses. In the rare cases where no degradation is seen, IL–SEM may provide comfort that the studied catalyst is ready for up-scaling and can be moved towards industrial applications. However, although it is usually considered a non-invasive technique, the interpretation of IL–SEM measurements may get more complicated. When, for example, IL–SEM is used to study the degradation of surfactant-capped Ag nanocubes employed as electrocatalysts of CO 2 electroreduction, nanoparticles subjected to the electron beam during pre-electrolysis imaging may lose some of their catalytic activity due to the under-beam formation of a passive organic contamination layer. Although the entirety of the catalyst obviously degrades, the spot mapped by IL–SEM reflects no or little changes during electrolysis. The aim of this paper is to shed light on an important limitation of IL–SEM: extreme care is necessary when applying this method for catalyst degradation studies, especially in case of nanoparticles with surface-adsorbed capping agents. [ABSTRACT FROM AUTHOR]

The atmospheric hydroformylation of olefins with FA as syngas alternative over L1 -Rh(acac)CO) 2 catalytic system (L1 = Xantphos) • Rh-catalyzed hydroformylation of olefins with formic acid as syngas alternative. • Insight into decomposition of formic acid to CO as well as H 2. • Characterizations by in situ FT-IR and high-pressure 1H NMR spectroscopic techniques. Formic acid (FA) is one kind of important bulk chemicals, which is recognized as a sustainable and eco-friendly energy carrier to transport H 2 via dehydrogenation or CO via decarbonylation. Expectantly, FA upon decomposition into H 2 and CO could be used as the syngas alternative for hydroformylation. In this paper, the behaviors of FA to release H 2 as well as CO following the distinct pathways were carefully investigated for the first time, and then established a new hydroformylation protocol free of syngas. It was found that the atmospheric hydroformylation of olefins with formic acid (FA) as syngas alternative was smoothly fulfilled over Xantphos (L1) modified Rh-catalyst under mild conditions (80 °C, Rh concentration 1 mol %, 14 h), resulting in >90% conversion of the olefins along with the high selectivity to the target aldehydes (>93%). By using FA as syngas source, the side-reaction of olefin-hydrogenation was greatly depressed. The in situ FT-IR and the high-pressure 1H NMR spectroscopic analyses were applied to reveal how FA behaves dually as CO surrogate and hydrogen source over L1 -Rh(acac)(CO) 2 catalytic system, based on which the deeply insight into the catalytic mechanism of hydroformylation of olefins with FA as syngas alternative was offered. [ABSTRACT FROM AUTHOR]

• Carbon dioxide (CO 2) capture and utilization (CCU) over noble metal catalysts. • Eliminating CO 2 emissions at the source. • Hydrogenation of amine captured CO 2 to methanol at <150 °C. • Intermediates include ethyl carbonate, formic acid, ethyl formate. • Methanol formation relies on synergy between noble metal and base. Carbon dioxide (CO 2) capture and utilization (CCU) offer a response to greenhouse gas emissions whereas they are often conducted separately, resulting in a high energy demand for the CO 2 separation process. The capture reagent chemically binds the CO 2 molecule, activating the stubborn CO 2 to a more active species. The direct conversion of the captured and activated CO 2 to the value-added chemicals will simplify the CO 2 utilization process, leading to a strong energy-saving effect by omitting the CO 2 separation process. In this paper, the commercial and the self-synthesized noble metal catalysts were evaluated in the hydrogenation of amine captured CO 2 in ethanol at 140–165 °C, which is demonstrated to produce the main product methanol in the presence of K 3 PO 4 or using MgO as a catalyst support. The Pd-based catalyst was superior to the Rh, Pt or Ru based catalyst in the hydrogenation of amine captured CO 2 towards methanol. The superior Pd/MgO catalyst was characterized by XRD, XPS, SEM, HRTEM, and DRIFTS analysis. NMR measurement and the ATR FTIR measurements were used to determine the initial intermediate to be ethyl carbonate. Mechanistic insight to the methanol formation indicates that the synergistic effect of Pd and a base cascaded the reactions: the reduction of ethyl carbonate to formic acid, the dehydration between formic acid and ethanol to form ethyl formate, and the hydrogenolysis of ethyl formate to methanol and ethanol. The ethyl formate intermediate was hydrogenated to methanol by Pd, wherein basic condition (K 3 PO 4 or MgO) was responsible for the activation of the carbonyl group of the ethyl formate. [ABSTRACT FROM AUTHOR]

Constructing and adopting a county-level panel dataset containing carbon emission (CO 2) and economic information between 2009 and 2017, this paper employs the continuous difference-in-differences (DID) model and is among the first to conduct an evaluation of the CO 2 reduction effect of China's emission trading scheme (ETS) pilot markets from the dual perspectives of price and scale. The empirical results emerge that the increase of transaction price and the expansion of transaction volume in ETS pilots have a persistent and significant influence on CO 2 reduction. Parallel to this, it is found the rising of transaction price in ETS can be effective on CO 2 reduction by improving the energy structure transition, however, optimization of industrial structure and the development of ICT might be the essential channels driven by the expansion of transaction volume. Last, this paper identifies the synergistic effect on different sorts of contaminants and find it is more substantial to those with the gas state. This paper implies that the policymakers should fully excavate the market-oriented environmental regulation tools from transaction price and volume perspective of views for the well achieving the climate ambitions of carbon peak and neutrality. • This article estimates the carbon emission reduction effect in of China's ETS pilots from the dual perspective of price and scale point of view. • The switch of China's carbon ETS regional pilots to national unified one can make the carbon emissions experience a wave of decline about 6.162%. • By estimating the possible synergistic effect on pollution of ETS market pilots, which find it is more significant to pollutants with gas phase. [ABSTRACT FROM AUTHOR]

There is concern that the carbon prices generated through climate policies are too low to create the incentives necessary to stimulate technological development. This paper empirically analyzes how the Swedish carbon dioxide (CO 2 ) tax and the European Union emission trading system (EU ETS) have affected productivity development in the Swedish pulp and paper industry 1998−2008. A Luenberger total factor productivity (TFP) indicator is computed using data envelopment analysis. The results show that climate policy had a modest impact on technological development in the pulp and paper industry, and if significant it was negative. The price of fossil fuels, on the contrary, seems to have created important incentives for technological development. Hence, the results suggest that the carbon prices faced by the industry through EU ETS and the CO 2 tax have been too low. Even though the data for this study is specific for Sweden, the models and results are applicable internationally. When designing policy to mitigate CO 2 emissions, it is vital that the policy creates a carbon price that is high enough – otherwise the pressure on technological development will not be sufficiently strong. [ABSTRACT FROM AUTHOR]

Due to lower-cost energy supplies elsewhere, Europe needs resource efficient technologies to safeguard the competitiveness of its energy-intensive industries. The technical feasibility of the CCU value chain components (carbon capture, transportation and utilization) has been widely studied in literature. However infrastructural, regulatory and business strategic issues have received less attention. A review of the relevant policies (e.g. European Emissions Trading Scheme, Renewable Fuels and Waste Directives) has been performed. Stakeholder engagement and the stakeholder influence mapping was used to examine potential climate change, circular economy, renewable energy and regional industrial development policies that can support CO 2 utilization value chains. The main contribution of the paper is to outline potential benefits of policies to foster the production and uptake of CO 2 -derived products such as methanol, polyurethane and mineral construction aggregates. Another outcome is to illustrate the role of key policy-making stakeholders in assessing the suitability of current statutes and the impact of potential changes. An important finding was that the development of connectivity infrastructure is a key missing enabler and more attention to policy on infrastructure is required. Finally, the work examines the justification for a CO 2 Utilization Directive, comparable to the Carbon Capture and Storage Directive, but considering the current complexity of the European Union (EU) policy landscape. • Analysis of all European policies relevant to the development of CO2 utilization. • Stakeholder influence analysis for the future development of CCU policy. • Recommendation to consider CO2 as a material for the circular economy. • Stakeholder engagement with industry participants and European institutions. • Rationale for regional burden sharing of risk in developing CCU infrastructure. [ABSTRACT FROM AUTHOR]

The principle of "common but differentiated responsibility", as a key concept of the United Nations Framework Convention on Climate Change (UNFCCC), acknowledges the conditions for a generally acceptable and differentiated pricing mechanism on carbon emissions. With reference to this principle, carbon price determination has become a necessary instrument for sustainable policies. Considering the development gaps and the historical responsibility of the OECD's countries, a single carbon price would raise a major issue of equity between "developed" and "developing" countries. Although from a climate perspective each molecule of CO 2 produces the same level of damage despite the nature or the location of the activity generating the emissions, all CO 2 emissions are not on an equal footing. Indeed, some are necessary to improve the lives of people in "developing" countries when others can be considered not indispensable, especially beyond a certain level of development. In this policy paper, we explain how the price of carbon should be fixed according to a reference price depending on the Human Development Index (HDI) and CO 2 emissions per capita. The HDI criterion enables to integrate progressivity into taxation while distinguishing what is essential from what is not. By taking a reference price based on the HDI, countries with low HDIs should pay a lower carbon price. However, with same HDI levels, countries with higher CO 2 emissions should pay a penalty on the reference price. Our policy paper analyses the benefits of a differentiated and progressive carbon pricing mechanism to facilitate intergovernmental cooperation for a more sustainable economy. • This policy paper analyses the benefits of a differentiated and progressive carbon pricing. • The article proposes carbon prices based on the Human Development Index (HDI) and C 0 2 emissions per capita. • The proposed mechanism is an efficient mean to facilitate intergovernmental cooperation and modify the global energy mix for a sustainable growth. [ABSTRACT FROM AUTHOR]

• Determination of CO 2 -broadening coefficients of lines in the ν 3 band of methane. • The half-widths were measured using a high resolution diode-laser spectrometer. • The parameters were deduced from the Voigt, Rautian-Sobel'man and Galatry profiles. In this paper, CO 2 -broadening coefficients of 11 lines in the ν 3 band of CH 4 , located between 2906 and 2959 cm−1, were measured at room temperature using an improved tunable diode-laser spectrometer. Each line was recorded for 4 different pressures, ranging from 20.15 to 60.20 mbar. The experimental determination of the CO 2 -broadening coefficients was performed by fitting a theoretical profile on the experimental line shape for each line recorded at each pressure. The Voigt, Rautian-Sobel'man and Galatry models were therefore used. The ratio between the present CO 2 -broadened results and the data available in the literature for air-broadening is investigated and compared to the ratio between N 2 - and air-broadening. The γ CO 2 / γ air presents significant differences with the ratio γ N 2 / γ air as well as a large scattering. This shows the need to make dedicated studies, both experimentally and theoretically, for CO 2 -broadening coefficients. [ABSTRACT FROM AUTHOR]

Precipitation and impregnation are two common methods to synthesize heterogeneous catalysts. In this paper we compare the stability and activity of silica-supported catalysts prepared by precipitation or by impregnation, having comparable support morphology and copper weight loading. To obtain catalysts with comparable support morphology, plate-like silica was prepared from the precipitated catalyst. This porous, high surface area plate-like silica was subsequently impregnated with an aqueous copper solution and reduced in hydrogen. Catalysts characterization revealed that catalysts prepared by impregnation contained heterogeneities, present as particles significantly larger than the vast majority, whereas catalysts prepared by precipitation displayed a narrow particle size distribution. In particular the catalyst prepared by impregnation with a copper weight loading of 34 wt% displayed heterogeneities in the form of large particles, which were detrimental for both activity and stability in methanol synthesis from synthesis gas. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of CO 2 (ECR-CO 2 ) to fuels, storing renewable electricity energy from clean energy and recycling CO 2 in a carbon neutral and green manner, has been proven to be a feasible strategy for energy storage and conversion. However, the catalysts that drive ECR-CO 2 generally suffer from low activity and stability, as well as poor product selectivity. To improve catalyst performance, tuning particle size and morphology has been a key strategy. In this paper, Bi nanoparticle catalysts (Bi 30-80 ) are accurately reconstructed with polyethylene glycol (PEG) using a simple aqueous chemical reduction method. The Bi 30-80 catalyst exhibits Faradaic efficiencies as high as 94.7% for ECR-CO 2 to produce formate at −0.83 V vs. RHE, and retain their activity for at least 10 h. At more positive potential of −0.78 V vs. RHE, a Faradaic efficiency of 91.3% is reached and the catalysts show no degradation over 20 h of continuous electrolysis. The markedly enhanced activity of a typical Bi 30-80 catalyst is due to its appropriate particle size and morphology, assisted by PEG in the catalyst synthesis, which give high electrochemical surface areas and more catalytically active sites. Some visible catalyst deactivation is initially identified, for example, after long-time electrolysis (45 h), caused by a change in morphology and the formation of (BiO) 2 CO 3 , confirmed by SEM and XRD. In addition, the effects of HCO 3 − concentration (or pH) of the electrolyte and the electrode potential impact on catalytic activity and product selectivity of the Bi 30-80 catalyst are also studied for performance optimization. [ABSTRACT FROM AUTHOR]

In 2019, aviation was responsible for 2.6% of world CO 2 emissions as well as additional climate impacts such as contrails. Like all industrial sectors, the aviation sector must implement measures to reduce its climate impact. This paper focuses on the simulation and evaluation of climate scenarios for air transport. For this purpose, a specific tool (CAST for "Climate and Aviation - Sustainable Trajectories") has been developed at ISAE-SUPAERO. This tool follows a methodology for the assessment of climate impacts adapted to aviation. Firstly, models for the main levers of action, such as air traffic, aircraft energy consumption and energy decarbonization, are provided using trend projections from historical data or assumptions from the literature. Second, the evaluation of scenarios is based on aviation carbon budgets, which are also extended to non- CO 2 effects using the concept of GWP*. Several scenario analyses are performed in this paper using CAST allowing different conclusions to be drawn. For instance, the modelling of the scenarios based on the more recent ATAG (Air Transport Action Group) commitments shows that aviation would consume 6.5% of the world carbon budget for +1.5 °C. Some illustrative scenarios are also proposed. By allocating 2.6% of the world carbon budget to aviation, it is shown that air transport is compatible with a +2 °C trajectory when the annual growth rate of air traffic varies between −1.8% and +2.9%, depending on the technological improvements considered. However, using the same methodology for a +1.5 °C trajectory shows that a drastic decrease in air traffic is necessary. Lastly, analyses including non- CO 2 effects emphasize the importance of implementing specific strategies for mitigating contrails. • Development of the open-access tool CAST to simulate aviation climate trajectories. • Modelling of different levers of action to decarbonise aviation. • Use of carbon budgets to assess the sustainability of scenarios. • Analysis of industrial scenarios with regard to the Paris Agreement. • Investigation of sustainable scenarios for different technological forecasts. [ABSTRACT FROM AUTHOR]

We have reported earlier that modification of commercial graphite Pt-supported catalysts with Teflon fluorinated polymeric coating of a very strong hydrophobic nature can significantly improve catalytic activity for aerial oxidation of water-insoluble alcohols such as anthracene methanol in supercritical carbon dioxide (scCO2). Thus, this paper presents some further characterization of these new catalyst materials and the working fluid phase during the catalysis. Using the same Teflon-modified metal catalysts, this paper addresses the oxidation of another water-insoluble alcohol molecule, m-hydrobenzoin in scCO2. It is found that conversion and product distribution of this diol oxidation critically depend on the temperature and pressure of the scCO2 used, which suggest the remarkable solvent properties of the scCO2 under these unconventional oxidation conditions. [Copyright &y& Elsevier]

The UK's 2050 net-zero emission target is one of the most ambitious goals in the world. Organisations should play a vital role by communicating a sufficient level of carbon emission information with the stakeholders. Motivated by the necessity of measuring the level of carbon disclosure, this paper provides a unique carbon emission disclosure measurement based on a sample of UK firms from 2013 to 2019. We apply different methods to assess the validity and reliability of our developed measurement. The results suggest that our measurement captures the actual CO2 emission, including scope 1, scope 2, and also captures the environmental, social and governance (ESG) score. Additionally, we explore the association between capital expenditure, corporate governance and the level of carbon emission disclosure. Further, the results show a positive relationship between capital expenditure and carbon emission disclosure. Also, there is a significant positive relationship between internal governance and carbon emission disclosure. Moreover, the analysis suggests that internal governance strengthen the relationship between capital expenditure and carbon emission disclosure. We also use quantile regression, and the findings show that capital expenditure and internal governance have a positive impact on carbon emission disclosure under all quantiles. Our data suggest that capital expenditure declines within the UK by around 53% over the last six years. Following the reduction in capital expenditure, the results demonstrate 39% decline in the CO2 emission level. The results also indicate that for every $1 million capital expenditure, approximately 2.75 Metric tons of carbon dioxide (MtCO2) emissions increase. Business investment is around 70% of the UK's total investment. Therefore, the reduction in capital expenditure is one of the primary reasons that might explain the decrease in the UK's overall CO2 emission level. The unique findings of this paper are relevant to the government, management and standard-setters. • Novel measurement of corporate carbon emission disclosure. • Our novel carbon disclosure measurement encapsulates actual CO2 emission. • This measure also captures Environmental, Social and Governance (ESG) score. • Capital expenditure is positively related with carbon emission disclosure. • Internal governance moderates this relationship. [ABSTRACT FROM AUTHOR]

In this paper, two isostructural Co/Ni-based coordination polymers [Co(Htzbt)(bpy)] n (1) and [Ni(Htzbt)(bpy)] n (2) have been synthesized by solvothermal method using 2-(1H-1,2,4-triazol-1-yl)benzene-1,3,5-tricarboxylic acid (H 3 tzbt) and 4,4′-Bipyridine (bpy) as mixed ligands. The two compounds exhibited three dimensional (3D) pillared-layer structure and relative high water-stability. Interestingly, through rationally selection of functional ligand and metal ions, isolated N sites and carboxylic acid sites as well as unsaturated metal sites were combined in the structure of the final compounds. Benefit from these multiple active centers in the framework, the as-synthesized compounds exhibit enhanced catalytic activity in both cycloaddition of CO 2 with epoxides and hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol. In particular, compound 1 showed superior catalytic performance under mild conditions. Additionally, 1 could maintain relative high efficiency for at least four cycles, exhibiting potential application in practical catalysis. In this paper, two isostructural 3D pillared-layer Co/Ni-based coordination polymers, namely [M(Htzbt)(bpy)] n (M ​= ​Co2+, 1 ; M ​= ​Ni2+, 2) have been synthesized, which show good catalytic activity in both cycloaddition of CO 2 with epoxides and hydrogenation of 4-nitrophenol to 4-aminophenol, due to the multiple active sites inside their structures. Image 1 • Two Co/Ni-based coordination polymers have been successfully synthesized based on H 3 tzbt and bpy ligands. • The two compounds ​present similar 3D pillared-layer frameworks, which are stable against hot and humid conditions. • Multiple active centers have been designed within the frameworks as potential catalytic sites. • The two compounds ​also exhibit good catalytic properties. • The unique structures endow ​the compounds ​with multifunctional applications. [ABSTRACT FROM AUTHOR]

The primary objective of this paper is to investigate the isolated impacts of hydroelectricity consumption on the environment in Malaysia as an emerging economy. We use four different measures of environmental degradation including ecological footprint, carbon footprint, water footprint and CO 2 emission as target variables, while controlling for GDP, GDP square and urbanization for the period 1971 to 2016. A recently introduced unit root test with breaks is utilized to examine the stationarity of the series and the bounds testing approach to cointegration is used to probe the long run relationships between the variables. VECM Granger causality technique is employed to examine the long-run causal dynamics between the variables. Sensitivity analysis is conducted by further including fossil fuels in the equations. The results show evidence of an inverted U-shaped relationship between environmental degradation and real GDP. Hydroelectricity is found to significantly reduce environmental degradation while urbanization is also not particularly harmful on the environment apart from its effect on air pollution. The VECM Granger causality results show evidence of unidirectional causality running from hydroelectricity and fossil fuels consumption to all measures of environmental degradation and real GDP per capita. There is evidence of feedback hypothesis between real GDP to all environmental degradation indices. The inclusion of fossil fuel did not change the behavior of hydroelectricity on the environment but fossil fuels significantly increase water footprint. [ABSTRACT FROM AUTHOR]

The paper demonstrates the possibility of measuring the carbon dioxide (CO 2 ) concentration in atmospheric air using Raman spectroscopy. Three methods have been studied for deriving the CO 2 concentration from the Raman spectra (the peak intensity ratio, the integrated intensity ratio, the contour fit method). The best results were obtained when the contour fit method is applied for Raman spectra processing. In this case the deviations from reference mixtures of known concentration were below 3 ppm. Methods for improving the sensitivity of the Raman gas analysis method are proposed and the possibility for using this technique for the simultaneous determination of the concentrations of significant amount of greenhouse gases in air with single device is discussed. [ABSTRACT FROM AUTHOR]

This paper estimates the efficiency of the power generation sector in the USA by using Window Data Envelopment Analysis (W-DEA). We integrate radial and non-radial efficiency measurements in DEA using the hybrid measure while we extend the proposed model by considering good and undesirable outputs as separable and non separable. Then in the second stage, we perform parametric and non-parametric econometric techniques in order to model the relationship between the calculated environmental efficiencies and economic growth in attaining sustainability. Our empirical findings indicate a stable N-shape relationship between environmental efficiency and regional economic growth in the case of global and total pollutants but an inverted N-shape in the case of local pollutants. This implies that attention is required when considering local and global pollutants and the extracted environmental efficiency scores. A clear message to policy makers and government officials is that climate change which calls for economic, environmental and social concern should be analyzed according to its dispersion and regional dimension. [ABSTRACT FROM AUTHOR]

This paper reports the experimental values of the interfacial tension between a gas mixture (CO 2  + H 2 ) and water measured with the pendant drop method. The measurements were conducted for temperatures from 271.2 K to 280.2 K and pressures up to 7.0 MPa, at increments of 1 MPa. These temperature-pressure ranges were nearly close to the (CO 2  + H 2 ) hydrate-stability-zone but each result is obtained without existence of any hydrate. The temperature dependency of the interfacial tension in this system could not be observed, but the interfacial tension decreased almost linearly with increasing pressure, indicating that the observed decrease was caused by an increase in adsorption of the gas phase onto the liquid water with pressure. The gradient of the interfacial tension, with respect to the pressure, was confirmed to be determined by the gas phase composition. The interaction between gases has a marginal influence on the interfacial tension between the (CO 2  + H 2 ) gas mixture and water. [ABSTRACT FROM AUTHOR]

This paper developed internationally compatible methods for delineating boundaries of urban areas in China. By integrating emission source data with existing official statistics as well as using rescaling methodology of data mapping for 1 km grid, the authors constructed high resolution emission gridded data in Beijing-Tianjin-Hebei (Jing-Jin-Ji) region in China for 2012. Comparisons between urban and non-urban areas of carbon emissions from industry, agriculture, household and transport exhibited regional disparities as well as sectoral differences. Except for the Hebei province, per capita total direct carbon emissions from urban extents in Beijing and Tianjin were both lower than provincial averages, indicating the climate benefit of urbanization, comparable to results from developed countries. Urban extents in the Hebei province were mainly industrial centers while those in Beijing and Tianjin were more service oriented. Further decomposition analysis revealed population to be a common major driver for increased carbon emissions but climate implications of urban design, economic productivity of land use, and carbon intensity of GDP were both cluster- and sector-specific. This study disapproves the one-size-fits-all solution for carbon mitigation but calls for down-scaled analysis of carbon emissions and formulation of localized carbon reduction strategies in the Jing-Jin-Ji as well as other regions in China. [ABSTRACT FROM AUTHOR]

[Display omitted] • The phase equilibrium conditions for gas hydrates formed in CO 2 + cyclopentane + deuterium oxide system. • Temperature and pressure ranges were from 285.35 K to 293.65 K and from 0.279 MPa to 2.735 MPa, respectively. • Powder X-ray diffraction analysis were performed for both CO 2 + cyclopentane + D 2 O hydrate and CO 2 + cyclopentane + H 2 O hydrate. This paper reports characterization of clathrate hydrate formed in CO 2 + cyclopentane + deuterium oxide (D 2 O) system with the phase equilibrium determination and the powder X-ray diffraction (PXRD) measurements towards the development of hydrate-based tritium separation technology. Four-phase (CO 2 gas + liquid cyclopentane + liquid D 2 O + hydrate) equilibrium conditions were measured using the isochoric procedure in the pressure range from 0.279 MPa to 2.735 MPa and the temperature range from 285.35 K to 293.65 K. The equilibrium temperature of CO 2 + cyclopentane + D 2 O system is always higher by 2.0 K to 2.4 K compared to that of CO 2 + cyclopentane + H 2 O system. The detailed crystallographic properties of both CO 2 + cyclopentane + D 2 O hydrate and CO 2 + cyclopentane + H 2 O hydrate including the lattice constants, the radii and volumes of each cage and the cage occupancy were estimated by the PXRD analysis. Based on the obtained results, implications for the development and operation of D 2 O-hydrate-based process are discussed. [ABSTRACT FROM AUTHOR]

Amongst the current alternatives, algae were proven to be a promising source of biofuel, which is renewable and capable of meeting world demand for transportation fuels. However, a suitable lipid extraction method that efficiently releases the lipids from different algal strains remains a bottleneck. The multifarious pretreatment methods are prevalent in this field of lipid extraction, and therefore, this article has critically reviewed the various lipid extraction methods for ameliorating the lipid yield from algae, irrespective of the strains/species. Physical, mechanical, and chemical are the different types of pretreatment methods. In this review, methodologies such as homogenization, sonication, Soxhlet extraction, microwave treatment, and bead-beating, have been studied in detail and are the most commonly used methods for lipid extraction. Specific advanced/emerging processes such as supercritical CO 2 extraction, ionic liquid, and CO 2 switchable solvent-based algal lipid extraction are yet to be demonstrated at pilot-scale, though promising. The extraction of lipids has to be financially conducive, environmentally sustainable, and industrially applicable for further conversion into biodiesel. Hence, this paper discusses variable pretreatment for lipid extraction and imparts a comparative analysis to elect an efficient, economically sound lipid extraction method for pilot-scale biodiesel production. • Multifarious pretreatment methods for algal lipid extraction were reviewed. • Conventional methods like sonication, microwave, homogenization was discussed. • Chemical/solvent-based processes for various algal strains were critically analyzed. • Ionic liquids and CO 2 switchable solvent based algal lipid extraction was addressed. • Advances and mechanism in supercritical CO 2 extraction process was presented in-detail. [ABSTRACT FROM AUTHOR]

Accurate identification of the early stages of coal-fire combustion is important for effectively controlling the spread of coal fires. CO 2 and CO, as characteristic gases in the early stage of coal fire combustion, can be effectively monitored by in-situ monitoring near the surface. However, in the previous in-situ monitoring methods, the influence of surface meteorological and soil factors on the release law of characteristic gases is often ignored. Therefore, this paper considers the complexity of the geological conditions in the coal fire area, a system, and equipment for obtaining the near-surface CO 2 and CO variation laws in the early stage of coal fire combustion proposed by the concentration gradient method (CGM). The system and equipment realize the simultaneous online coupling of multi-area and multi-parameter data and conduct field investigations on the Wuda coal fire area. The results show that in the early stage of coal combustion, the change patterns of CO 2 and CO concentrations in different regions are anomalous, and the CO 2 concentration was higher than the CO concentration. The CO 2 and CO concentrations in shallow soil increased with the increase of soil depth, and compared with other areas, the CO 2 and CO concentration was the highest. The shallow soil and CO 2 were identified as the key areas and characteristic gases for identifying the early stage of coal-fire combustion. The CO 2 flux (CF) of different shallow soil depths decreased with increased soil layer depth. Variation of soil-surface CO 2 flux (S-SCF) estimated by flux extrapolation method (FLEM). The change of S-SCF is controlled by meteorological and soil factors, and there is a certain connection between it and the "respiration phenomenon" in the fissure area. Thus, this study provides a theoretical basis for effectively identifying the early stages of coal-fire combustion. • A system and equipment are proposed to obtain the emission law of near-surface spontaneous combustion gas in the early stage of coal fire combustion. • The wavelet analysis method was used to obtain the potential relationship between the shallow soil and the fractured area in the early stage of coal fire combustion. • The responses of soil-surface CO 2 fluxes to meteorological and soil factors were explored using SEM (structural equation model) and WTC (wavelet transform coherence). [ABSTRACT FROM AUTHOR]