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Air has the advantage of abundance and easy availability, so it is suitable to be used as a synthetic raw material and energy source. However, the triggering of inert small molecules in the air, like O2, N2, and CO2, is a kinetically complex and energetically challenging multistep reaction. Photocatalysis brings hope for this challenge, but obstacles remain in many aspects. Here, aiming at the key difficulties of the photocatalytic activation and conversion of these three inert small molecules, i.e., regulating electronic structure, active sites, charge carrier separation and mobility, and reaction energy barrier, we propose the concept of functional customization strategy of ultrathin two-dimensional materials for achieving more efficient activation and better performance, including thickness control, vacancy engineering, doping operation, single-atom site fabrication, and composite construction. The in-depth understanding of the functional customization will provide more profound guidance for designing photocatalysts that specialize in activating and converting inert small molecules.

There may be trade‐offs in the allocation patterns of recent photosynthetic carbon (RPC) allocation in response to environmental changes, with a greater proportion of RPC being directed towards compartments experiencing limited resource availability. Alternatively, the allocation of RPC could shift from sources to sinks as plants processing excess photosynthates. It prompts the question: Does the pattern of RPC allocation vary under global changes? If so, is this variation driven by optimal or by residual C allocation strategies? We conducted a meta‐analysis by complicating 273 pairwise observations from 55 articles with 13C or 14C pulse or continuous labeling to assess the partitioning of RPC in biomass (leaf, stem, shoot, and root), soil pools (soil organic C, rhizosphere, and microbial biomass C) and CO2 fluxes under elevated CO2 (eCO2), warming, drought and nitrogen (N) addition. We propose that the increased allocation of RPC to belowground under sufficient CO2 results from the excretion of excess photosynthates. Warming led to a significant reduction in the percentage of RPC allocated to shoots, alongside an increase in roots allocation, although this was not statistically significant. This pattern is due to the reduced water availability resulting from warming. In conditions of drought, there was a notable increase in the partitioning of RPC to stems (+7.25%) and roots (+36.38%), indicative of a greater investment of RPC in roots for accessing water from deeper soil. Additionally, N addition led to a heightened allocation of RPC in leaves (+10.18%) and shoots (+5.78%), while reducing its partitioning in soil organic C (−8.92%). Contrary to the residual C partitioning observed under eCO2, the alterations in RPC partitioning in response to warming, drought, and N supplementation are more comprehensively explained through the lens of optimal partitioning theory, showing a trade‐off in the partitioning of RPC under global change. [ABSTRACT FROM AUTHOR]

Abstract Background Microbial electrosynthesis (MES) is a biocathode-driven process, in which electroautotrophic microorganisms can directly uptake electrons or indirectly via H2 from the cathode as energy sources and CO2 as only carbon source to produce chemicals. Results This study demonstrates that a hydrogen evolution reaction (HER) catalyst can enhance MES performance. An active HER electrocatalyst molybdenum carbide (Mo2C)-modified electrode was constructed for MES. The volumetric acetate production rate of MES with 12 mg cm−2 Mo2C was 0.19 ± 0.02 g L−1 day−1, which was 2.1 times higher than that of the control. The final acetate concentration reached 5.72 ± 0.6 g L−1 within 30 days, and coulombic efficiencies of 64 ± 0.7% were yielded. Furthermore, electrochemical study, scanning electron microscopy, and microbial community analyses suggested that Mo2C can accelerate the release of hydrogen, promote the formation of biofilms and regulate the mixed microbial flora. Conclusion Coupling a HER catalyst to a cathode of MES system is a promising strategy for improving MES efficiency.

The potential would be an important issue for enhancing photocatalytic HER and CO 2 photoreduction selectivity. Herein, the Co 3 O 4 /Ti3+-TiO 2 hollow S-scheme heterojunction is fabricated via continuous light modification-chemical-annealing-reduction method. Evaluated by photocatalytic performance, the as-prepared Co 3 O 4 /Ti3+-TiO 2 hollow S-scheme heterojunction exhibits remarkable photocatalytic performance enhancement than single TiO 2 , including hydrogen evolution (∼396.16 μmol/g·h, ∼15 folds) and CO 2 photoreduction (H 2 /CH 4 /CO: ∼20.32/80.57/9.85 μmol/g·h, ∼20 folds), and achieves CO 2 photoreduction to CH 4 selectivity enhancement, which can be mainly ascribed to the synergism of Ti3+/O v and S-scheme heterojunction. There, Ti3+/O v can not only increase the solar efficiency, but also decrease the energy barrier of H+ and ∗CO photoreduction to enhance HER and CO 2 to CH 4 selectivity, including promote the H+ diffusion and CO 2 absorption. Additionally, the formed Co 3 O 4 /Ti3+-TiO 2 S-scheme heterojunction can promote the photo-generated carrier separation/transportation. Also, the hollow 3D structure obtained by ZIF-67 self-template can increase solar efficiency and stability. [Display omitted] • Ti3+/O v can decrease ∗CO photoreduction energy barrier to enhance CH 4 selectivity. • Ti3+/O v with shallow donor level can increase carrier concentration. • Heterojunction can promote carriers separation/transport via appropriate potential. • Hollow 3D structure can increase interface heterojunction and stability. • ZIF-67 self-template can decrease photocatalyst corrosion. [ABSTRACT FROM AUTHOR]

Solar-induced chlorophyll fluorescence (SIF) has a high correlation with Gross Primary Production (GPP). However, studies focusing on the impact of drought on the SIF-GPP relationship have had mixed results at various scales, and the mechanisms controlling the dynamics between photosynthesis and fluorescence emission under water stress are not well understood. We developed a leaf-scale measurement system to perform concurrent measurements of active and passive fluorescence, and gas-exchange rates for winter wheat experiencing a one-month progressive drought. Our results confirmed that: (1) shifts in light energy allocation towards decreasing photochemistry (the quantum yields of photochemical quenching in PSII decreased from 0.42 to 0.21 under intermediate light conditions) and increasing fluorescence emissions (the quantum yields of fluorescence increased to 0.062 from 0.024) as drought progressed enhance the degree of nonlinearity of the SIF-GPP relationship, and (2) SIF alone has a limited capacity to track changes in the photosynthetic status of plants under drought conditions. However, by incorporating the water stress factor into a SIF-based mechanistic photosynthesis model, we show that drought-induced variations in a variety of key photosynthetic parameters, including stomatal conductance and photosynthetic CO2 assimilation, can be accurately estimated using measurements of SIF, photosynthetically active radiation, air temperature, and soil moisture as inputs. Our findings provide the experimental and theoretical foundations necessary for employing SIF mechanistically to estimate plant photosynthetic activity during periods of drought stress. [ABSTRACT FROM AUTHOR]

The preparation of methanol chemicals through CO2 and H2 gas is a positive measure to achieve carbon neutrality. However, developing catalysts with high selectivity remains a challenge due to the irreversible side reaction of reverse water gas shift (RWGS), and the low-temperature characteristics of CO2 hydrogenation to methanol. In-plane sulfur vacancies of MoS2 can be the catalytic active sites for CH3OH formation, but the edge vacancies are more inclined to the occurrence of methane. Therefore, MoS2 and a series of MoS2/Nix and MoS2/Cox catalysts doped with different amounts are prepared by a hydrothermal method. A variety of microscopic characterizations indicate that Ni and Co doping can form NiS2 and CoS2, the existence of these substances can prevent CO2 and H2 from contacting the edge S vacancies of MoS2, and the selectivity of the main product is improved. DFT calculation illustrates that the larger range of orbital hybridization between Ni and MoS2 leads to CO2 activation and the active hydrogen is more prone to surface migration. Under optimized preparation conditions, MoS2/Ni0.2 exhibits relatively good methanol selectivity. Therefore, this strategy of improving methanol selectivity through metal doping has reference significance for the subsequent research and development of such catalysts. [ABSTRACT FROM AUTHOR]

Decreasing particle size (like thickness) is a common strategy to enhance the activities of catalysts. In this work, we have synthesized two coppers, which are bismuth-based metal-organic framework (CuBi-MOF) catalysts with different thicknesses (134.8 and 2.0 nm). In contrast to common expectations, large thickness CuBi-MOF has exhibited superior activities as a comparison to its small-thickness counterpart in terms of carbon dioxide electroreduction to produce formate, characteristic of high selectivity (Faraday efficiency >90%), a wide window of potential (-0.6 to -1.6 V vs. reversible hydrogen electrode), and large current densities (up to -380mAcm-2). The mechanism study has been performed by using density functional theory calculations, which highlight the strong synergic effect between Cu and Bi sites in large-thickness CuBi-MOF for activating CO2 molecules. Consequently, large-thickness CuBi-MOF could show smaller Gibbs free energies compared to its small counterpart for binding with reaction intermediate (*COOH, 1.1 vs. 1.8 eV). The result of this work could provide new insights into catalyst design toward a number of electrochemical systems. [ABSTRACT FROM AUTHOR]

Summary: The greater duckweed (Spirodela polyrhiza 7498) exhibits trophic diversity (photoautotrophic, heterotrophic, photoheterotrophic, and mixotrophic growth) depending on the availability of exogenous organic carbon sources and light.Here, we show that the ability to transition between various trophic growth conditions is an advantageous trait, providing great phenotypic plasticity and metabolic flexibility in S. polyrhiza 7498.By comparing S. polyrhiza 7498 growth characteristics, metabolic acclimation, and cellular ultrastructure across these trophic modes, we show that mixotrophy decreases photosynthetic performance and relieves the CO2 limitation of photosynthesis by enhancing the CO2 supply through the active respiration pathway. Proteomic and metabolomic analyses corroborated that S. polyrhiza 7498 increases its intracellular CO2 and decreases reactive oxygen species under mixotrophic and heterotrophic conditions, which substantially suppressed the wasteful photorespiration and oxidative‐damage pathways. As a consequence, mixotrophy resulted in a higher biomass yield than the sum of photoautotrophy and heterotrophy.Our work provides a basis for using trophic transitions in S. polyrhiza 7498 for the enhanced accumulation of value‐added products. [ABSTRACT FROM AUTHOR]

We developed an approach to realize the comprehensive utilization of CO2 and glycerol by smartly design a nanocatalyst, which concerns the coupling of catalytic reactions and the separation or capture process. Specifically, MgFe‐CO32−‐LDHs with different thickness were fabricated by employing atmospheric CO2 as carbon source and an atomic‐level interface was constructed by introducing Pt single atoms to obtain series of Pt/MgFe‐LDHs nanocatalysts. During a catalytic assessment, the CO32− confined within interlayer was in situ converted when integrated with glycerol oxidation under irradiation. The optimal nanocatalyst exhibited a decent conversion efficiency of CO32−‐CO‐CH4 and near 100% selectivity of secondary hydroxy group in glycerol. DFT calculation, isotope‐labeled experiments and in situ spectrograph characterization revealed possible coupling reaction mechanism. More importantly, the nanocatalyst exhibited impressive reusability for at least six 6 runs. The developed multiple coupling process will be an alternative and promising procedure for the waste and low‐valued sources synergetic utilization. [ABSTRACT FROM AUTHOR]

One mononuclear Mn(III) complex [MnIIIL(H2O)(MeCN)](ClO4) (1) and one hetero-binuclear complex [(CuIILMnII(H2O)3)(CuIIL)2](ClO4)2·CH3OH (2) have been synthesized with the Schiff base ligand (H2L = N,N′-bis(3-methoxysalicylidene)-1,2-phenylenediamine). Single crystal X-ray structural analysis manifests that the Mn(III) ion in 1 has an octahedral coordination structure, whereas the Mn(II) ion in 2 possesses a trigonal bipyramidal configuration and the Cu(II) ion in 2 is four-coordinated with a square-planar geometry. Electrochimerical catalytic investigation demonstrates that the two complexes can electrochemically catalyze water oxidation and CO2 reduction simultaneously. The coordination environments of the Mn(III), Mn(II), and Cu(II) ions in 1 and 2 were provided by the Schiff base ligand (L) and labile solvent molecules. The coordinately unsaturated environment of the Cu(II) center in 2 can perfectly facilitate the catalytic performance of 2. Complexes 1 and 2 display that the over potentials for water oxidation are 728 mV and 216 mV, faradaic efficiencies (FEs) are 88% and 92%, respectively, as well as the turnover frequency (TOF) values for the catalytic reduction of CO2 to CO are 0.38 s−1 at −1.65 V and 15.97 s−1 at −1.60 V, respectively. Complex 2 shows much better catalytic performance for both water oxidation and CO2 reduction than that of complex 1, which could be owing to a structural reason which is attributed to the synergistic catalytic action of the neighboring Mn(III) and Cu(II) active sites in 2. Complexes 1 and 2 are the first two compounds coordinated with Schiff base ligand for both water oxidation and CO2 reduction. The finding in this work can offer significant inspiration for the future development of electrocatalysis in this area. [ABSTRACT FROM AUTHOR]

CO2 methanation is one of the vital reactions to utilize CO2 and realize power to gas process. To decrease the CO2 capture cost and alleviate the hot spots during the strong exothermic methanation reaction, here, we report a coupling of CO2 capture process with in situ CO2 methanation process through a ceramic‐molten carbonate (MC) dual phase membrane reactor over the Ni‐based catalyst. The performance of the membrane reactor was systematically investigated and compared with the traditional fixed‐bed reactor. The results show that the performance of the membrane reactor is higher than that of the fixed‐bed reactor, since the produced steam through the methanation process can be partially removed through the dual‐phase membrane, which promotes the reaction shift to right side. A stability test shows no obvious degradation within 32 h. These results indicate that the membrane reactor is promising for coupling CO2 capture with in situ methanation process. [ABSTRACT FROM AUTHOR]

A micro-pulse lidar system incorporating differential absorption lidar (DIAL) and coherent Doppler wind lidar (CDWL) is proposed and demonstrated. Due to the high signal-to-noise ratio (SNR) of the superconducting nanowire single-photon detector (SNSPD), the DIAL channel achieves high sensitivity in CO2 measurement. Meanwhile, the CDWL channel is used to obtain the horizontal wind field. In the process of the optimization and calibration of the DIAL receiver, specifically, mode scrambling and temperature control of the connecting fiber between the telescope and the SNSPD enhance the stability and robustness of the system. Horizontal scanning of the CO2 concentration and the wind field is carried out in a 6 km range over a scanning span of 60° with a radial resolution of 150 m and 15 s. The results show that the hybrid lidar system captures the spatial distribution of CO2 concentration and the wind field simultaneously. The horizontal net CO2 flux in a radius of 6 km is estimated by integrating the CO2 concentration and the wind transport vector, indicating different characteristics of horizontal net CO2 fluxes in an industrial area, a university campus, and a park. During most of the experiment, CO2 flux remained positive in the industrial area, but balances fell to nearly zero on the campus and in the park. The horizontal net fluxes averaged over 24 h in the three areas are 3.5 × 105 ppm·m2·s−1, 0.7 × 105 ppm·m2·s−1, and 0.1 × 105 ppm·m2·s−1. [ABSTRACT FROM AUTHOR]

The CO2 reduction reaction (CRR) represents a promising route for the clean utilization of renewable resources. But mass‐transfer limitations seriously hinder the forward step. Enhancing the surface hydrophobicity by using polymers has been proved to be one of the most efficient strategies. However, as macromolecular organics, polymers on the surface hinder the transfer of charge carriers from catalysts to reactants. Herein, we describe an in‐situ surface fluorination strategy to enhance the surface hydrophobicity of TiO2 without a barrier layer of organics, thus facilitating the mass transfer of CO2 to catalysts and charge transfer. With less obstruction to charge transfer, a higher CO2, and lower H+ surface concentration, the photocatalytic CRR generation rate of methanol (CH3OH) is greatly enhanced to up to 247.15 μmol g−1 h−1. Furthermore, we investigated the overall defects; enhancing the surface hydrophobicity of catalysts provides a general and reliable method to improve the competitiveness of CRR. [ABSTRACT FROM AUTHOR]

• Fractal polyhedral MOFs (Cu-TATB) is synthesized for CO 2 /N 2 separation. • Small-sized pores can capture CO 2 , while large-sized pores facilitate N 2 escape. • Different sized channels successfully achieving the goal of gas separation. A fractal polyhedral pore structural MOFs (Cu-TATB) is synthesized from the coordination of tridentate ligands (H 3 TATB) and Cu 4 clusters. This material is characterized by single crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis. The structure contains two different pore structures, including closed octahedral cages and open tetrakaidecahedron cages. The material has been successfully utilized for the separation of CO 2 /N 2 due to the fractal structure of the channel with different pore sizes. Under optimized temperature, Cu-TATB adsorbed a large amount of CO 2 and only negligible amount of N 2 , and the selectivity reaches 27. Breakthrough experiments demonstrated that this material can efficiently separate N 2 and CO 2. This structure further demonstrates the infinite potential of 3D MOFs with diverse pore structures in applications such as CO 2 adsorption and separation. [ABSTRACT FROM AUTHOR]

• First accounting of CO 2 mineralization and utilization potential of tailings sand at the ownership scale in China. • Innovative ARIMA-cloud model predicted tailings sand production and consumption. • Analyzed carbon sinks under scenarios of technological leapfrog and elevated utilization. • Screened potential spatial clusters of mineralized carbon sinks from tailings sand. • The feasibility of mineralization project layouts was judged by enterprise size. The use of tailings sand for CO 2 mineralization and utilization (CMU) has been emerging globally, offering a sustainable solution for repurposing tailings sand while establishing a stable carbon sink. Despite several reports that evaluated process performance and project benefits, existing research has not delved into the project layout focusing on the tailings pond facility and the feasibility considerations from a cluster and ownership perspective. Conducting facility-scale refined mineralized carbon sink (MCS) and layout feasibility assessment is a key issue that needs to be addressed urgently. Here, we accounted for CMU potential (CMUP) of tailings sand using a sample of 6219 tailings pond ownerships in China, predicted future annual carbon sinks through an innovative ARIMA-cloud model, and analyzed the feasibility of project layouts within potential clusters concerning enterprise size. Our results indicate that the CMUP of accumulated tailings sand in China amounts to 1817.87 Mt. In a combined scenario involving future technological leapfrogging and increased utilization, the average annual carbon sink by 2030 is projected to be 24.73 Mt. A considerable reduction in project layout feasibility across all scenarios was observed due to the mismatch between carbon clusters and enterprise size. Our study reveals that CMU using tailings sand should be regarded as one of the essential green technologies in the portfolio of strategic Chinese CO 2 mitigation. However, we highlight the necessity of aligning cluster programs with the support capacity of the ownership enterprise to ensure the optimal project success. [Display omitted] [ABSTRACT FROM AUTHOR]

Calcium looping cycle integrated CO 2 capture and conversion (CaL-ICCC) is a promising technology for addressing energy and environmental issues related to anthropogenic CO 2 emissions. This technology offers high efficiency, low cost, and enhanced safety, as it eliminates the need for purification, compression, transportation, and storage processes. To achieve integrated CO 2 capture and conversion (ICCC), the development of new and highly efficient catalysts is crucial. Dual functional materials (DFMs), which consists of absorbents and catalysts, playing a key role in bridging this gap. Recently, DFMs have garnered considerable attention, with a focus on the development of efficient, selective, and stable catalysts. This review summarizes the current advancements in metal oxide-doped CaO-based sorbents and metal oxide-supported catalytic conversion of CO 2 in the reverse gas shift reaction (RWGS), specifically in terms of absorbent and catalyst performance, selectivity, and stability. Additionally, the mechanism of CaO-based CO 2 capture and in-situ conversion in CaL-RWGS processes is discussed. The challenges and future prospects in terms of material stability and durability, technological and economic hurdles, dual functional material structures, and the application of AI technologies are also addressed. [Display omitted] • The performance of metal oxide doped CaO-based adsorbents were discussed. • The performance of metal oxide as supported in RWGS was discussed. • The mechanisms of absorbents and DFMs of CO 2 conversion were examined individually. • Potential future development trends were recommended in this work. [ABSTRACT FROM AUTHOR]

The projected rise in atmospheric CO 2 levels to 550 ppm by mid-century may reduce protein, iron, and zinc levels in certain cereal crops by 3–17 %. In China, staple foods provide nearly 50 % of total energy and 40 % of essential nutrients, and their cultivation exacerbates environmental stress; adjusting staple food consumption may bring environmental and health benefits. Using China Health and Nutrition Survey (CHNS) data, this study compared current staple food consumption (S BAU) to an optimized balanced diet scenario with the consumption of whole grains and legumes replaces excessive refined grains. Findings reveal that S BAU falls short of recommended nutrient intake (RNI), while the optimized scenario offsets the nutritional impact of the elevated CO 2 , exceeding 95 % of the RNI for zinc and iron from staple food. Additionally, transition to the optimized scenario also reduces greenhouse gas emissions and blue water consumption by 7 % and 39 %, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

For carbon dioxide concentration (XCO2) distribution, the improvement of spatial and temporal resolution is very important in some scientific studies (e.g., studies of the carbon cycle and assessment of carbon emissions based on top-down theory). However, carbon sniffing satellites based on passive theory (e.g., Gosat-2, OCO-2, and OCO-3) are susceptible to cloud and aerosol interference when the data are captured. Therefore, the data collected by carbon sniffing satellites have relatively low utilization, especially in some regions where data gaps exist. Here, we present the Carbon Dioxide Coverage (CDC) dataset, an innovative theory to obtain high spatial and temporal resolution maps of XCO2 distribution by combining spatial attributes and extracted temporal attributes from the GOSAT satellite series data. This theory is divided into the following three parts. Firstly, several background values in the raw GOSAT data were removed through data pre-processing, and for spatial attributes, GOSAT satellite data gap areas were filled by combining adjacent GOSAT data and empirical Bayesian kriging (EBK) theory in the study area. Secondly, for the temporal attributes, we constructed a time profile parameter library, based on the GOSAT data of the time series to extract the temporal parameters from a specific formula at each point of the study area. Finally, for the integration of temporal and spatial information, based on the GOSAT satellite data and the populated data based on spatial attributes, we assign the temporal parameter information from the time parameter library to each pixel location in the study area, combining the transfer component analysis (TCA) theory, and then combine the assigned parameters with specific formulas to complete the prediction of XCO2 distribution. For temporal resolution, both the GOSAT_FTS_L3_V2.95 and CDC datasets are monthly-averaged resolution datasets from 2010 to 2020. And for spatial resolution, the CDC dataset is 0.25° resolution with a significant improvement compared to GOSAT_FTS_L3_V2.95 which is 2.5° resolution. And the dataset contained 136 files. Besides, for the data validation part, we used OCO-2 satellite data from 2009 to 2020 and TCCON data at mid and low latitudes, respectively. This CDC dataset and the original data from the TCCON sites were compared on a monthly-averaged scale. And the results showed that R2 was 0.9686, and RMSE was 1.3811 ppm. We also derived statistical monthly averaged XCO2 from OCO-2 data and compared it with the data set from our theory. And our evaluation index R was greater than 0.7, by comparison with OCO-2 during 2014-2020. Finally, to assess the accuracy of the algorithm, we compared the predicted results with the input data for the period of 2009-2020. And the comparison results show that the mean value of R2 is 0.93 and the mean value of RMSE is 0.53 ppm during 2010-2020. Data gaps produced by sniffer satellites are disturbed by factors such as clouds and aerosols and can be filled by this mapping technique is mentioned in this paper. This technique improves the utilization of XCO2 and the accuracy and resolution of the CDC dataset is sufficient for scientific applications. And the CDC dataset is publicly available at https://doi.org/10.6084/m9.figshare.17826404.v4 (Zhang et al., 2022), which is of significance for a multitude of scientific carbon research. [ABSTRACT FROM AUTHOR]

Atomically dispersed metal catalysts have been widely used in electrocatalysis because of their outstanding catalytic activity and high atomic utilization efficiency. As an extension of single‐atom catalysts (SACs), dual‐atom catalysts (DACs) provide new insights for the development of atomic‐scale catalysts. Higher metal loading and more flexible active sites endow DACs with improved catalytic performance as well as optimized reaction mechanism model. In this review, DACs are firstly classified according to their configurations and metal sites. Subsequently, the synthetic strategies and characterization techniques of DACs are introduced. Furthermore, the applications of DACs are exemplified in various electrocatalytic reactions, including oxygen reduction reaction, oxygen evolution reaction and carbon dioxide reduction reaction. Finally, the prospects to be expected and challenges to be faced with are discussed. [ABSTRACT FROM AUTHOR]

We investigate herein the reaction mechanism of dry reforming of methane over Pt clusters in combination with kinetic measurements and in-situ characterizations, proposing that the undissociated CO 2 involves in C-H bond activation and the direct reaction between CO 2 * and CH 4 * is considered as the kinetically relevant step. [Display omitted] • CO 2 is probably undissociatively involved in the process of CH 4 activation over Pt/MgO. • A Langmuir-Hinshelwood model is established to explain the DRM reaction mechanism. • Rates of dry reforming of CH 4 are lower than those of CH 4 -O 2 and CH 4 -H 2 O due to different oxidation capacities. • The reaction between CH 4 * and CO 2 * to form HCOO* and CH 3 * is probably the RDS. We investigate here systematically C-H bond activation mechanism on Pt/MgO with O 2 , H 2 O and CO 2 , and find that dry reforming of CH 4 (DRM) experiences a weak activity compared with reforming or partial oxidation of CH 4. Pressure dependence shows negligible effect of CO determined within a broad CO pressure regime (<10 kPa at high-pressure CH 4 /CO 2 (20.3 kPa) and <0.3 kPa at low-pressure CH 4 /CO 2 (0.8 kPa)) and competitive adsorption between CH 4 and CO 2 (0.8 kPa), suggesting that CO 2 is involved in CH 4 activation as an entire molecule. Based on established Langmuir-Hinshelwood model, reaction between adsorbed CH 4 and CO 2 to yield formate and methyl species was kinetically relevant. Both CO 2 and CH 4 derivatives are the most abundant surface intermediates, being confirmed by in situ FTIR and quasi - in-situ XPS. The oxidizability of oxidant was quantitatively evaluated; CO 2 has the weakest oxidizability, probably making DRM less active. DRM is structure-sensitive with terrace site of Pt as active component. The influence of reverse water–gas shift was dominant in modifying selectivity. This work will certainly reconcile contradictories on CH 4 activation mechanism and push the industrial application of CH 4 forward. [ABSTRACT FROM AUTHOR]

The significance of converting CO 2 into valuable feedstock is highly emphasized with the carbon neutrality vision. Generally, CO and H 2 are usually applied as the protective gases during CO 2 electrolysis in nickel based Solid Oxide Electrolysis Cell (SOEC). In this paper, the effects of H 2 and CO as protective gases on the performance of a Ni-YSZ (yttria stabilization zirconia) based SOEC are studied. The electrode processes of the cell are investigated by the electrochemical impedance spectroscopy (EIS) and calculated distribution of relaxation times (DRT) results. The results show that CO makes little difference on the performance of the cell while the cell shows a superior performance with H 2 as protective gas, indicating different mechanisms behind. The distinct discrepancies in characteristic frequency ranges of electrode processes with the CO 2 –CO and CO 2 –H 2 mixtures show that the replacement of CO by H 2 changes the reduction pathway of CO 2 from electrochemical reduction to thermochemical reduction, and only steam is electrolyzed. However, the direct injection of steam deteriorates slightly the performance of SOEC. The effect of reverse water gas shift (RWGS) reaction on the electrochemical performance of SOEC is explored and its effect of delaying the concentration polarization and extending the limiting current density is confirmed. Furthermore, the unique pattern of flattened j-V curve at high applied current of CO 2 electrolysis is repeatedly emphasized. • The performance of SOEC with H 2 as protective gas was superior compared to that with CO. • The existence of H 2 changed the reduction pathway of CO 2 from electrochemical reduction to thermochemical one. • The effect of RWGS reaction of extending the limiting current density was proved. • The unique pattern of flattened j-V curve at higher applied current of exclusive CO 2 electrolysis was emphasized. [ABSTRACT FROM AUTHOR]

[Display omitted] The current research on the CO 2 RR process mainly focuses on the high selectivity of a single product and the material selectivity in the path process [1], [2] Guo et al., 2019. There are relatively few studies on changes and causes. In this work, TiO 2 /TiO formed by in-situ oxidation was used as a photocatalyst for CO 2 reduction. The structure of this semiconductor/metal-like heterojunction makes the internal electric field appear in the catalyst, which greatly improves the activity of the photocatalytic reaction. During the test, it was found that the hydrogenation product gradually appeared in the reaction product due to the appearance of TiO 2. In the absence of a sacrificial agent, the catalyst exhibited a high HCOOH selectivity and obtained a considerable yield of 46.37 μmol g−1h−1. After adding the sacrificial agent triethanolamine (TEOA), TiO 2 /TiO showed good CO production ability. As the reaction progressed, CH 4 was gradually produced. DFT calculations confirmed that the structure of the heterojunction has lower workfunction for the CO 2 hydrogenation option, and the energy band at the contact position is curved. The construction of this system has guiding significance for the construction of light-driven CO 2 hydrogenation products in the future. [ABSTRACT FROM AUTHOR]

The impregnation and ion exchange methods were employed to prepare the Ni-modified clinoptilolites (CPs). Their physicochemical properties and structural features were evaluated by various characterizations, such as XRD patterns, SEM and TEM images, Raman and FT-IR spectra, XPS and H 2 -TPR, N 2 sorption isotherms, and TG analysis. The results demonstrated that the loaded Ni nanoparticles were highly dispersed on the lamellar surfaces of the synthesized CPs. Meanwhile, their CH 4 and CO 2 dry reforming reactions (DRM) at 500–900 °C were conducted utilizing Ni species as active sites. The results demonstrated that the Ni-loaded CPs exhibited greater catalytic activity than the Ni-exchanged CPs, besides that, the Ni-loaded CPs demonstrated the highest catalytic stability at 700 °C. However, the carbon deposition of the Ni-loaded CPs seemed more difficult to eliminate than that of the Ni-exchanged CPs in the DRM durations. These results elucidate the excellent performances of the developed Ni-modified CPs for designing more stable and efficient Ni-based DRM catalysts. [Display omitted] • Ni-modified clinoptilolite (CP) was synthesized for CH4-CO2 reforming reaction. • DRM catalytic activity of Ni-loaded CP is higher than that of Ni-exchanged CP. • Ni-loaded CP showed an excellent DRM catalytic activity. • The well-dispersed Ni-nanoparticle was distributed in lamellar surface of CP. • Limitation of diffusion and adsorption of reactant and intermediate was overcome. [ABSTRACT FROM AUTHOR]