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Zinc nanoparticles were electro-deposited along the fibres of carbon paper (CP) substrate uniformly in a salt-induced pre-phase separation region solution. The as-prepared Zn/CP electrode was used for electro-reduction of CO 2 and exhibited a Faradaic efficiency towards CO of 97.6% with a current density of 340 mA cm−2 in an H-type cell, which is the best result to date. [Display omitted] Efficient electrode design is crucial for the electrochemical reduction of CO 2 to produce valuable chemicals. The solution used for the preparation of electrodes can affect their overall properties, which in turn determine the reaction efficiency. In this work, we report that transition metal salts could induce the change of two-phase ionic liquid/ethanol mixture into miscible one phase. Pre-phase separation region near the phase boundary of the ternary system was observed. Zinc nanoparticles were electro-deposited along the fibres of carbon paper (CP) substrate uniformly in the salt-induced pre-phase separation region solution. The as-prepared Zn(1)/CP electrode exhibits super-wettability to the electrolyte, rendering very high catalytic performance for CO 2 electro-reduction, and the Faradaic efficiency towards CO is 97.6% with a current density of 340 mA cm −2, which is the best result to date in an H-type cell. [ABSTRACT FROM AUTHOR]

A scalable papermaking process was employed herein to manufacture cellulosic papers from native and phosphorylated cellulose microfibers (referred to as CMF and PCMF, respectively) impregnated with polyethyleneimine (PEI) for Direct Air Capture (DAC) applications. These papers were analyzed in terms of their physico-chemical properties using several techniques. The impact of PEI content on desorbing the co-adsorbed H 2 O and CO 2 from the air, as well as on the anisotropic microporous network, was explicitly analyzed. The results indicated that phosphorylation promotes the uptake of both CO 2 and H 2 O in the corresponding neat and PEI-loaded papers, reaching a superior CO 2 adsorption capacity of ∼0.7–0.9 mmol.g−1 for PCMF papers versus 0.07–0.3 mmol.g−1 for CMF papers. Furthermore, the CMF and PCMF papers exhibited H 2 O adsorption capacities in the range of 1.5–1.8 mmol.g−1 and 2.2–3.8 mmol.g−1, respectively. This work further highlights the combined role of phosphorylation and favorable PEI impregnation in tuning the cellulose CO 2 adsorption properties under humid conditions, facilitating the rapid release of the adsorbed CO 2 under mid conditions. [Display omitted] • Manufacturing of scalable solid cellulosic papers with amine functionalities and enhanced carbon capture. • Microstructural and chemical characterization of amine functionalized paper with various amine ratios. • Valorization of Alfa biomass in Carbon capture applications. • The combined role of phosphorylation and PEI impregnation in tuning the H 2 O and CO 2 co-adsorption properties. [ABSTRACT FROM AUTHOR]

A recent commentary by Santhosh and Ravindran on our paper (Int. J. Hydrogen Energy 2014, 39:10,606) demonstrated that the interaction between H 2 and MXene (Sc 2 C and Ti 2 C) phases are not Kubas-type and should be of weak physisorption, and thus made a conclusion that 2D Sc 2 C and Ti 2 C are not suitable for practical hydrogen storage applications. In this responses, we recalculated hydrogen adsorption on 2D Sc 2 C and Ti 2 C by using different exchange-correlation functionals. And based on the calculated results, bare MXenes (especially the Ti 2 C) are suitable as hydrogen storage materials at temperatures of several tens degrees lower than room temperature. And the hydrogen adsorptions on the MXenes terminated with oxygen group were also investigated. Among the Ti 2 C, Sc 2 C and their oxygen-functional counterparts, the binding energy of H 2 on Sc 2 CO 2 surface is the closest to the ideal range of 0.16–0.42 eV/H 2 at ambient conditions, and thus the Sc 2 C with oxygen group is expected to be more suitable as hydrogen storage materials. [ABSTRACT FROM AUTHOR]

• Black liquor gasification was coupled with calcium looping. • Calcium looping for CO 2 capture and H 2 production was compared. • CO 2 capture route (39 €/t) was less expensive than H 2 production route (48.8 €/t). • CO 2 avoided cost was highly dependent on capital cost of black liquor gasification. • Export of H 2 had the lowest CO 2 avoided cost among black liquor gasification cases. Although considered one of the major energy-intensive industries (EIIs), the pulp and paper industry has also the potential for energy production from an industrial waste, black liquor. This study proposes black liquor gasification (BLG) coupled with calcium looping (CaL) as a CO 2 capture route for the pulp and paper industry. BLG with H 2 production (BLG-CaL-H 2), BLG with gas turbine combined cycle (BLG-CaL-GT) or with solid oxide fuel cell (BLG-CaL-SOFC) were considered. The dependence of carbon capture and storage (CCS) cost on the natural gas, limestone, electricity imported and H 2 sale prices aside the expenditures related with BLG-CaL were evaluated. The CCS route, based on CaL retrofitted to the pulp and paper plant, was found to have a lower cost of CO 2 avoided (39.0 €/tCO 2) when compared with BLG-CaL (48.8–57.1 €/tCO 2). Between the BLG-CaL scenarios, BLG-CaL-H 2 presented the lowest cost of CO 2 avoided (48.8 €/tCO 2) but the highest energy penalty. Based on the thermodynamic performance, it was shown that CaL retrofit and BLG-CaL-SOFC presented the best overall performance, turning the electricity importer reference plant into electricity exporter. The economic sensitivity showed that the capital requirement of BLG-CaL has a strong effect on the cost of CO 2 avoided for all alternatives. The H 2 production is also strongly affected by the H 2 sale price while BLG-CaL-SOFC and BLG-CaL-GT are strongly dependent on natural gas price. [ABSTRACT FROM AUTHOR]

The combustion of biomass and waste paper sludge in a fluidized bed is ecologically profitable. However, a large amount of by-product with high hydraulic reactivity is produced and is considered as wastes. Most of the time the waste paper fly ash (WPFA) goes to landfills, therefore new utilization methods are necessary. In some countries, the high content of metallic and metalloids trace elements (MMTE) in WPFA, more specifically Barium (Ba) and Lead (Pb) makes its valorization difficult. In this paper, the Lightweight Aggregates (LWA) was produced from WPFA by granulating with water in high-intensity granulator. Since WPFA is rich in CaO, the addition of water promotes rapid setting and hydration compared to other types of ash. In this study, different granulation parameters were investigated, such as the rotation modes between the steel pan and the impeller, the rotation speed of the steel pan, the granulation time, in order to improve the mass percentage of the targeted LWA (2–16 mm). In order to evolve the immobilization potential of Ba and Pb, a carbonation process was performed, exposing the manufactured LWA to pure carbon dioxide (CO 2) gas at laboratory scale. The physical, morphological, thermal and mechanical characterizations were performed on LWA for use in mortars, concretes or civil engineering constructions. Results have demonstrated the influence of the rotation mode between the steel pan and the on the distribution of WPFA inside the steel pan and the change in the growth rate of the granules can be observed. Increased density and improved compressive strength with low porosity and water absorption were also found in LWA after carbonation. This was due to the occurrence of both a carbonation reaction and a hydration reaction. Furthermore, the results of thermogravimetry and SEM-EDS confirmed the formation of hydrated phases (ettringite, carboaluminates), also the formation of calcite in the pores and the external surface of the LWA. Regarding environmental aspects, the results have revealed that Ba and Pb were well immobilized in the solid matrix after carbonation. [Display omitted] • LWA was manufactured from WPA without any agglomerating agents. • The physical-chemical properties of LWA were improved after carbonation. • The resulted LWA meet the requirements of NF EN -13,055-1. • The microstructure of LWA was studied before and after carbonation. • Influence of time, mode and rotation speed on the size of the manufactured LWA. [ABSTRACT FROM AUTHOR]

A completely lab-made paper/graphene-based 3D pop-up device (3D-PP) for the analysis of carbaryl (CBR), a pesticide widely used in crop production, is proposed. The device is composed of a nitrocellulose sensor equipped with reduced graphene oxide (rGO) and a foldable 3D paper pop-up. The rationale of the device is based on 3D and 2D configurations to allow the whole analytical procedure. In the 3D arrangement sample pre-concentration and hydrolysis occur; after folding (2D), contact with the complementary nitrocellulose-based sensor is ensured. The sensor, constituted by nanostructured graphene film, allows to obtain the necessary electroanalytical performance. 3D-PP has been shaped and nanostructured using a CO 2 -laser plotter and finished using low-cost benchtop instruments, ensuring in-series manufacturing of the device modules. 3D-PP includes the main steps required for CBR determination, i.e. (i) pre-concentration/purification, (ii) hydrolysis, (iii) medium neutralization, and (iv) electrochemical detection. 3D-PP was challenged for CBR quantification in model solutions and different grain samples. The response linearity (1.5–33 μM) and LOD (0.4 μM) obtained ensures CBR determination at the European-law admitted maximum residue levels (MRL). As proof of applicability, to simulate contaminates samples, different grains (i.e. soft and durum wheat, kamut, and barley) were spiked, before extraction, with CBR at three concentration levels corresponding to 0.5x, 1x, and 1.5x MRL; in all cases, quantitative and reproducible recoveries were obtained (93–109%; RSD ≤ 6%, n = 3). 3D-PP is produced using cellulosic components and solvent-free approaches, includes all CBR analysis steps, and returns reliable results in 15 min, resulting portable and usable with a smartphone [Display omitted] • A paper/graphene-based device for integrated carbaryl (CBR) analysis is proposed. • CO 2 -laser was used to shape and nanostructure the paper-based platform. • Complete CBR analysis is strategically enclosed in a 3D foldable paper pop-up (3D-PP). • 3D-PP design and sensing ability allow CBR residues analysis at EU-law limits. • 3D-PP analysis ability was proven in soft and durum wheat, kamut, and barley. [ABSTRACT FROM AUTHOR]

The present study investigated the fresh, hardened, and physicochemical properties of CO 2 -cured belite-rich cement (BRC) paste incorporating hygiene tissue paper (HTP) as an additive. HTP was added at 0.5% and 1.0% by wt. of BRC paste. The BRC paste was prepared at a water-to-cement ratio of 0.4 and cured under water and carbonation. The results demonstrated that upon carbonation, the incorporation of HTP at 1.0% increases the CO 2 uptake and compressive strength of specimens by 18.60% and 22.29%, respectively. A pore structure analysis shows a decrease in the threshold pore size diameter with an increase in the HTP content for CO 2 -cured samples. An SEM analysis revealed precipitation and impregnation of calcites in and around the HTP microfiber particles. The incorporation of HTP under water curing on the other hand did not significantly influence the strength or the physicochemical properties. It was observed that HTP contributes to improving the properties of CO 2 -cured BRC paste in two ways; the porous structure of HTP provides pathways for the deep permeation of CO 2 into the matrix, and the surface of HTP offers an additional area for calcite precipitation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Filter paper is used as carbon source to prepare highly porous N-doped carbon. • KHCO 3 is chosen as the activator because it is safe and non-corrosive. • Addition of urea at the activation step significantly improves the surface area. • At 0 °C and 20 bar, the carbon shows high CO 2 uptake of 19.65 mmol/g. Herein, we presented the preparation of N-doped porous carbon from lab used filter paper. Filter paper was first carbonized at 500 °C. The obtained carbon was then pyrolyzed with KHCO 3 and urea. Effects of KHCO 3 activation on the carbons' physicochemical properties were thoroughly investigated. The derived carbon materials were also tested for CO 2 adsorption with pressure up to 20 bar. The carbons exhibited very high CO 2 uptake of 19.65 mmol/g at 0 °C and 20 bar. The correlations between adsorption performances and the carbons' physicochemical properties at 1/20 bar were analyzed and discussed. [ABSTRACT FROM AUTHOR]

Activated carbon fiber paper (ACFP) has the potential for adsorption due to their high surface area and low through resistance. In this work, free-standing ACFP was developed from fibrillated polyacrylonitrile (PAN) fiber through wet forming process combined with subsequent pre-oxidation, carbonization and CO 2 activation. A PFI refiner was used to prepare fibrillated PAN fibers with a beating degree of 7, 11, 25 and 60 oSR, respectively. As expected, PAN fibers with high beating degree improved surface area and fine fiber content, which resulted in the dense structure and low porosity of paper, thus influencing later stabilization and pyrolysis, as well as final properties of ACFP. With the increase of beating degree, the oxygen content of pre-oxidized PAN paper increased, but the cyclization index first decreased and then increased. ACFP with higher beating degree possessed higher BET surface area, pore volume and CO 2 uptake capacity. ACFP, prepared from freeze-dried PAN paper, performed better in physicochemical properties than that from plate-press drier under the same beating degree. This study exhibited that ACFP can be a special material featured by scale production, lightweight, and high microporosity of chemical adsorption and separation. [Display omitted] • ACFPs were prepared from fibrillated PAN fiber through wet forming process. • Effects of pore structure of PAN papers on physicochemical properties of ACFPs • CO 2 adsorption on ACFPs was a combined effects of physisorption and chemisorption. [ABSTRACT FROM AUTHOR]

Strategies for changing the conductivity of Li 2 CO 3 is introduced into the fabrication of Li-CO 2 battery. Benefitting from the favorable hierarchical architecture constructed (CPM-MnO 2), facile charge transfer occurs between catalytic surface and Li 2 CO 3 by –OH⋯O hydrogen bonds improves the metallicity of Li 2 CO 3 , facilitating the formation/decomposition of Li 2 CO 3 and bestowing an ultra-long-term stability of 1087 cycles (4348 h). Taking into account its simplicity, scalable character and outstanding performance, this hierarchical composite electrode paves an effective trajectory for the future development of highly efficient cathodes for durable metal-CO 2 batteries. [Display omitted] • Excellent hierarchical structure of MXene and MnO 2 on carbon paper was fabricated. • Enriched charge transfer occurred on MXene and the MnO 2 by OH⋯O hydrogen bonding. • The prepared batteries showed an ultra-long cycle lifetime and low overpotential. • The optimized electronic structure can improve the metallicity of Li 2 CO 3. • The accelerated decomposition of discharge products promoted CRR and CER kinetics. Lithium-CO 2 batteries are recognized as an essential strategy for efficient carbon sequestration and energy storage to achieve carbon neutrality. Their cycle-ability and polarization voltage, however, are hindered by high decomposition voltage (≈4.3–4.5 V) of insulating Li 2 CO 3. Herein, we report a significant advance toward the rational design of self-supporting and ultra-long cycle lifetime cathode for Li-CO 2 batteries, dependence on a favorable hierarchical architecture and rich charge transfer constructed by homogeneously distributed MnO 2 nanoplates rooted in the MXene surface supported by carbon paper. Detailedly, it exhibits impressive ultra-long-term stability of 1087 cycles (4348 h) with a low polarization gap (≈ 0.47 V) at a high current of 200 μA cm−2, which is outperformed by all the liquid electrolyte-based Li-CO2 batteries reported previously. Electronic structure analysis reveals that facile charge transfer occurs between catalytic surface and Li 2 CO 3 , springing from the –OH functional group (in MXene) to MnO 2 by –OH⋯O hydrogen bonds, which acts as charge transfer channels, improving the metallicity of Li 2 CO 3 and facilitating its decomposition and extending battery cyclability. This work paves an effective trajectory for the future development of highly efficient cathodes for durable metal-CO 2 batteries. [ABSTRACT FROM AUTHOR]

This work proposes to utilize supercritical CO 2 as a reaction medium for the acetylation of Hanji, a traditional Korean cellulose textile, to enhance its water repellency while retaining the other properties. We first examined the phase behavior of acetic anhydride and CO 2 mixtures, then a series of experiments were performed and statistically analyzed to find optimal operating conditions. Good surface hydrophobicity was attained in the optimized process within 4 h, shorter than classical non-catalytic liquid and gaseous processes. Hanji's tensile strength was also enhanced in the proposed process by a factor of 1.1, while it was aggravated in classical liquid processes. Hanji samples were slightly discolored in the proposed method, but the degree of discoloration was below the perception level. These results suggest that the proposed method has great potential to be used for the functionalization of cellulose-based textiles with a wide range of industrial applications. [Display omitted] • ScCO 2 -mediated acetylation was optimized to enhance Hanji's surface hydrophobicity. • Surface hydrophobicity is improved in scCO 2 -mediated acetylation within 4 h. • Tensile index increases by 11% in scCO 2 -mediated acetylation. • Tensile index decreases by 20% in classical acetylation methods. • Cellulose discoloration in scCO 2 -mediated acetylation is mild. [ABSTRACT FROM AUTHOR]

[Display omitted] • A bifunctional flexible Pt/TiO 2 -γ-Al 2 O 3 nanofiber paper was successfully prepared. • The PTA sample can efficiently decompose HCHO to CO 2 and H 2 O at room temperature. • PTA1 exhibited better catalytic activity and stability. • The surface coating of TiO 2 in PTA catalyst plays an important role for its performance. • The PTA sample also exhibits good filtration performance for fine particles. A flexible Pt/TiO 2 /γ-Al 2 O 3 nanfiber paper (PTA) was successfully prepared by an electrospinning-coating-NaBH 4 reduction method. The catalytic performance for formaldehyde (HCHO) oxidation over PTA with different Pt contents was investigated at room temperature. The results show that PTA exhibits higher catalytic activity and stability than Pt/γ-Al 2 O 3. The TiO 2 coating can promote the transformation of intermediate species and the desorption of CO 2. The PTA1 with 1 wt% Pt shows the best catalytic activity and good stability. In the view of activity and cost, 0.5 wt% Pt is the optimal Pt content. The TiO 2 coating not only plays an important role in improving the activity and stability of PTA, but also acts as a protective shell of γ-Al 2 O 3 fiber, which greatly reduces the risk of alkali etching during preparation and maintains the good flexibility of PTA. The dioxymethylene (DOM), formate/carbonate species, CO are the intermediate species in HCHO oxidation over PTA. In addition, PTA exhibits good filtration performance for fine particles as well as good fluid permeability. Because of the high efficiency and flexibility of PTA composite catalytic material for HCHO oxidation with good filtration performance for fine particles, it will be a promising candidate in air purification. [ABSTRACT FROM AUTHOR]

Hydrogen Economy and Cyclic Economy are advocated, together with the use of perennial (solar, wind, hydro, geo-power, SWHG) and renewable (biomass) energy sources, for defossilizing anthropic activities and mitigating climate change. Each option has intrinsic limits that prevent a stand-alone success in reaching the target. Humans have recycled goods (metals, water, paper, and now plastics) to a different extent since very long time. Recycling carbon (which is already performed at the industrial level in the form of CO 2 utilization and with recycling paper and plastics) is a key point for the future. The conversion of CO 2 into chemicals and materials is carried out since the late 1800s (Solvay process) and is today performed at scale of 230 Mt/y. It is time to implement on a scale of several Gt/y the conversion of CO 2 into energy products, possibly mimicking Nature which does not use hydrogen. In the short term, a few conditions must be met to make operative on a large scale the production of fuels from recycled-C, namely the availability of low-cost: i. abundant, pure concentrated streams of CO 2 , ii. non-fossil primary energy sources, and iii. non-fossil-hydrogen. The large-scale production of hydrogen by Methane Steam Reforming with CO 2 capture (Blue-H 2) seems to be a realistic and sustainable solution. Green-H 2 could in principle be produced on a large scale through the electrolysis of water powered by perennial primary sources, but hurdles such as the availability of materials for the construction of long-living, robust electrochemical cells (membranes, electrodes) must be abated for a substantial scale-up with respect to existing capacity. The actual political situation makes difficult to rely on external supplies. Supposed that cheap hydrogen will be available, its direct use in energy production can be confronted with the indirect use that implies the hydrogenation of CO 2 into fuels (E-fuels), an almost ready technology. The two strategies have both pros and cons and can be integrated. E-Fuels can also represent an option for storing the energy of intermittent sources. In the medium-long term, the direct co-processing of CO 2 and water via co-electrolysis may avoid the production/transport/ use of hydrogen. In the long term, coprocessing of CO 2 and H 2 O to fuels via photochemical or photoelectrochemical processes can become a strategic technology. • Hydrogen Economy and Cyclic Economy are discussed as an option for defossilizing anthropic activities and mitigating climate change. • In the short term, a few conditions must be met to make operative on a large scale the production of fuels from recycled-C. • In the medium-long term, the direct co-processing of CO 2 and water via co-electrolysis may avoid the production/transport/ use of hydrogen. • In the long term, coprocessing of CO 2 and H 2 O to fuels via photochemical or photoelectrochemical processes can become a strategic technology. [ABSTRACT FROM AUTHOR]

In our original paper (Buono et al., 2020), we investigated the dynamics of degassing (e.g., bubble nucleation and growth, degassing styles and regimes) of H 2 O-, CO 2 - and H 2 O-CO 2 -rich evolved alkaline melts over a wide range of variables (final pressures, decompression rates, volatile compositions and contents, temperatures) through a comprehensive review of previous and new HP (high pressure)-HT (high temperature) decompression experiments. The criticism of Allabar and Nowak regards a restricted part of our results, i.e., those concerning homogeneous bubble nucleation from our new experiments on H 2 O-rich melts. Their aim is refusing the classical nucleation theory (CNT), widely accepted in literature to explain homogeneous bubble nucleation in magmas, for evolved alkaline melts in favour of the spinodal decomposition. We found that the Authors of the Comment do not provide any new evidence in support of their thesis, but they keep only arbitrary and erroneous conjectures of our new experimental data. As we stated in our original paper, the evaluation of the specific bubble nucleation mechanism (CNT vs. spinodal decomposition) is beyond the scope of our research, as appropriate studies on both experimental and natural products would be necessary to shed light on this complex issue. [ABSTRACT FROM AUTHOR]

• 3D integrated Sn/CNT@N C gas diffusion electrode is proposed by phase inversion. • CNT@N C has integrated sponge-like microporous and finger-like macroporous layers. • The co-catalysis of N improves electron-proton-gas transfer for high performance. • Faraday efficiency of formate and CO is improved compared with Sn/carbon paper. A 3D integrated hierarchical porous N-doped Sn/CNT@N C gas diffusion electrode is proposed via phase inversion to synergistically improve electron-proton-gas transfer and efficiency of CO 2 reduction reaction (CO2RR). Hierarchical porous structure is tuned by the carbon nanotube additive during phase inversion, which integrates microporous layer and diffusion layer to decrease mass transfer resistance comparing with the 2D layer structure of commercial carbon paper. XPS results show that Sn/CNT@N C 800 contains pyridinic nitrogen and pyrrolic nitrogen with catalytic activity. EIS and LSV curves show that Sn/CNT@N C 800 is beneficial to reduce mass transfer resistance and increase current density after twice hydrophobic treatments. As a result, Sn/CNT@N C 800 shows higher CO 2 RR electrocatalytic activity. The reaction rate and Faraday efficiency of CO at 12 mA cm−2 increase by 40.2% and 40.6%, respectively compared with Sn/carbon paper. The reaction rate and Faraday efficiency of formate are also slightly higher than those of Sn/carbon paper. [Display omitted] [ABSTRACT FROM AUTHOR]

Currently, developing highly active and low-cost electrocatalytic materials for oxygen evolution reaction (OER) is an enormously grand challenge. Herein, we developed a novel and highly active Mn doped Co 2 Fe layer double hydroxide (LDH) electrocatalyst for OER. We discovered that these electrocatalytic materials can be directly grown on carbon papers to construct high-specific-surface-area electrode, which shows the lowest overpotential of 266 mV at 10 mA cm−2. Furthermore, after introducing Mn element, DFT + U calculation found that the ∗OOH of Fe-site on Co 2 Fe 0.67 Mn 0.33 LDH could draw more electrons than Co 2 Fe LDH due to the electronegativity differences between Fe-site on Co 2 Fe 0.67 Mn 0.33 LDH and Fe-site on Co 2 Fe LDH, which is reason that the energy level of Fe 3d (e g) was obviously downshifted by d-d repulsion of Mn 3d and Fe 3d in the neighboring sites of Co 2 Fe 0.67 Mn 0.33 LDH after doped Mn element, which leads to reduce charge-transfer energy from O 2p to Fe 3d (e g) to promote oxygen evolution processes for OER. Meanwhile, the band gap is also decreased after doped Mn element in Co 2 Fe LDH due to the downshifted e g orbital energy of Fe 3d. This study gives a general avenue to design and developing efficiently active LDH electrocatalysts for OER in the future. • Both bimetallic CoFe LDH and Mn doped CoFe LDHs directly grown on carbon paper are successfully synthesized. • The Co 2 Fe 0.67 Mn 0.33 LDH@NFs exhibits a small overpotential of 236 mV at 10 mA cm−1 for OER. • DFT + U studies reveal that the observed superb OER activity could be attributed to d-d repulsion of Mn 3d and Fe 3d. [ABSTRACT FROM AUTHOR]

The present work aims at the bioinspired synthesis of SnO 2 NPs, labeled as SnO 2 (bio) NPs using S. edule fruit. A mechanistic route of synthesis of SnO 2 NPs from its inorganic precursor has been proposed herewith. Carbon paper decorated SnO 2 (bio) NPs and its calcined counterpart SnO 2 (bio)- 800 NPs (800 °C) were employed for electrochemical CO 2 reduction. Both SnO 2 (bio) NPs and SnO 2 (bio)- 800 NPs were active towards CO 2 to formate (HCOO−) as the single product, in the liquid phase of 0.5 M KHCO 3 aqueous electrolyte and the maximum faradaic efficiency reached to 75.6–84.0%, respectively for 1 h of the chronoamperometric test. The predominant crystalline (110) facet in SnO 2 (bio)- 800 NPs might have caused a significant boost in faradaic efficiency for formate formation. [Display omitted] • Development of a tunable bioinspired process of SnO 2 NPs synthesis. • Mechanism of formation of SnO 2 NPs mediated by plant-based analyte. • SnO 2 NPs electrocatalyzed CO 2 conversion to HCOO with high Faradaic efficiency. • Selective HCOO formation because of highly crystalline (110) facet in SnO 2 NPs. [ABSTRACT FROM AUTHOR]

The photoelectrochemical conversion of CO 2 into valuable products represents an attractive method to decrease the external electrical bias required in electrochemical approaches. In this work, TiO 2 nanoparticles with enhanced optical properties, large surface area, appropriate morphology, and superior crystallinity are synthesized in supercritical medium to manufacture light-responsive photoanodes. The photoelectrochemical CO 2 reduction tests are carried out in continuous mode using a photoanode-driven filter-press cell illuminated with UV LED lights (100 mW cm-2), consisting on TiO 2 nanoparticles synthesized in supercritical medium (3 mg cm-2) supported onto porous carbon paper as the photoanode, a Cu plate cathode, and 1 M KOH aqueous solution as the reaction medium. The main products obtained from CO 2 are ethylene in the gas phase, together with methanol in the liquid phase. The results show that reaction performance is improved under UV irradiation towards ethylene (r = 147.4 μmol m−2 s−1; FE = 46.6%) and methanol (r = 4.72 μmol m−2 s−1; FE = 15.3%) in comparison with the system performance in the dark (ethylene: r = 24.2 μmol m−2 s−1 and FE = 38.2%; methanol not detected), which can be mainly ascribed to the superior photocurrent densities reached that affect the selectivity of the reaction. Besides, the maximum solar-to-fuels values achieved for ethylene (5.4%) and methanol (1.9%) are markedly superior to those observed with illuminated TiO 2 -P25 photoanodes under the same reactor configuration and experimental conditions (3.7% and 1%, respectively). Therefore, these results demonstrate the benefits of using TiO 2 -based materials synthesized in supercritical medium for a more efficient continuous photoelectroreduction of CO 2 to value-added products. [Display omitted] [ABSTRACT FROM AUTHOR]

The synergistic effect between metals is of great significance for improving the performance of materials, but the mechanism of synergistic catalytic of bimetallic has rarely been reported in the hydrolysis of sodium borohydride (NaBH 4 , SB). In this paper, a flower shaped Co 2 FeO 4 catalyst with high catalytic performance was selected from a series of Co x M 3-x O 4 (M = Fe, Ni, Cu) catalysts by controlling the composition. Based on the results of XPS characterization and density functional theory (DFT) calculation, the influence of component control on catalytic performance was discussed and explained from the perspective of electronic structure, and the "valence band center" and "D-band center" descriptors were introduced into the SB hydrolysis reaction. The simulation analysis results showed that the synergistic effect between Co–Fe elements resulted in the smallest center shift of the D band, the smallest binding energy of the hydrolysis reaction, and the best promoting effect on the electronic structure, manifested as the best catalytic performance. The calculation results were consistent with the XPS characterization results and the experimental results of hydrolysis performance testing, revealing the principle of bimetallic synergistic effect on catalytic performance. The synergistic effect between metals is of great significance for improving the performance of materials, but the mechanism of synergistic catalytic of bimetallic has rarely been reported in the hydrolysis of sodium borohydride (NaBH 4 , SB). In this paper, a flower shaped Co 2 FeO 4 catalyst with high catalytic performance was selected from a series of Co x M 3-x O 4 (M = Fe, Ni, Cu) catalysts by controlling the composition. Based on the results of XPS characterization and density functional theory (DFT) calculation, the influence of component control on catalytic performance was discussed and explained from the perspective of electronic structure, and the "valence band center" and "D-band center" descriptors were introduced into the SB hydrolysis reaction. The simulation analysis results showed that the synergistic effect between Co–Fe elements resulted in the smallest center shift of the D band, the smallest binding energy of the hydrolysis reaction, and the best promoting effect on the electronic structure, manifested as the best catalytic performance. The calculation results were consistent with the XPS characterization results and the experimental results of hydrolysis performance testing, revealing the principle of bimetallic synergistic effect on catalytic performance. [Display omitted] • Flower-like Co 2 FeO 4 showed the best catalytic performance. • The "D-band center" and "valence -band center" of Co 2 MO 4 were studied. • Composition and electronic control improve the catalytic performance of Co 2 MO 4. • The adsorption configuration of H 2 O on the Co 2 MO 4 (311) surface was studied. [ABSTRACT FROM AUTHOR]

[Display omitted] • Metal-organic ligand capped Cu 2 O NPs synthesis using analytes present in Sechium edule. • Cu 2 O NPs reduced charge transfer resistance by 98 %. • Elucidated mechanism of formation of Cu 2 O NPs and metal-organic intermediates leading to capping of NPs. • Cu 2 O NPs electrocatalyzed CO 2 reduction to HCOO− and improved product specificity. • Bio-inspired and chemically synthesized Cu 2 O NPs exhibited similar Faradaic efficiency in CO 2 reduction. Efficient electrocatalytic reduction of CO 2 to value-added chemicals is a promising and challenging task as well. In fact, synthesis of low-cost electrocatalysts in an environmentally benign process is the need of the hour. Bioactive compounds including polyphenols, reducing sugars, and ascorbic acid (AA) present in different plant organs are proven competent in reducing metal ions to their lower or zero oxidation states. The present study focuses on the synthesis of Cu 2 O NPs using the bioactive compounds present in Sechium edule fruit. The mechanistic pathways for the understanding of the formation of the face-centred cubic Cu 2 O NPs (37.5−42 nm) and metal-organic (intermediates) ligand leading to the development of its stabilizing cap are investigated in details. Cu 2 O NPs were decorated on the Toray carbon paper electrode. The modified electrodes could decrease the charge transfer resistance by 50 folds and catalyze the electrocatalytic CO 2 reduction to HCOO‾, a sole liquid product in 0.5 M KHCO 3 electrolyte with a faradaic efficiency of 65.3–66.6 % within 60 min as the existence of predominant Cu 2 O (111) NPs could be responsible for selective formation of formate. Nevertheless, Cu 2 O underwent oxidation to CuO after 100 voltammetric cycles which was resulted in declining CO 2 reduction reaction rate. The stability of Cu 2 O NPs and its delamination from the electrode surface was also studied in this work. [ABSTRACT FROM AUTHOR]

This paper explores green hydrogen-based carbon dioxide (CO 2) hydrogenation for the production of oxygenates, presenting it as a pivotal strategy for mitigating carbon emissions and advancing sustainable energy solutions. The conversion of CO 2 into oxygenates through hydrogenation emerges as a promising avenue, particularly in the context of transportation applications where the storage of hydrogen poses challenges. The substitution of fossil diesel and gasoline fuels with green hydrogen-derived dimethyl ether, or methanol/ethanol, is advantageous from a life cycle analysis (LCA) CO 2 emission perspective even without the capture of the CO 2. However, the greatest sustainability appeal is contingent on the crucial aspect of capturing CO 2 when utilizing these fuels, which is an aspect currently absent in the literature. This narrative review comprehensively explores catalytic processes, mechanisms, sustainability perspectives, and the current state of research in this evolving area. It encompasses both the production of oxygenates through CO 2 hydrogenation and the subsequent utilization of these oxygenates in fuel cells or combustion systems, emphasizing the integration of CO 2 capture technologies. The paper contributes to the discourse surrounding the environmental and technological dimensions of energy storage ecosystems, providing a holistic view of their potential to foster sustainable energy solutions. [ABSTRACT FROM AUTHOR]

Global shale oil is abundant in geological reserves, but there are widespread problems of difficult exploitation and unsatisfactory oil recovery. CO 2 injection in shale reservoirs can achieve effective exploitation of shale reservoirs and alleviate the current energy shortage. In this paper, investigations on shale oil in recent years were summarized and analyzed. Firstly, the reservoir characteristics and fluid properties of several shale reservoirs and their effects on CO 2 -enhanced oil recovery (CO 2 -EOR) were analyzed, including porosity, permeability, mineral composition, pore structure, geomechanical characteristics and organic matter properties of shale reservoirs, as well as the density, viscosity, gas-oil ratio and composition of shale oil. Subsequently, multiple mechanisms of CO 2 -EOR in shale reservoirs were revealed, including swelling, diffusion, viscosity reduction, extraction, miscibility, and competitive adsorption. The effects of temperature, pressure, CO 2 injection amount, oil composition and reservoir heterogeneity on different mechanisms were analyzed. The effects of nanopore confinement and CO 2 injection on the fluid phase were also analyzed. Then, the CO 2 storage forms of structural space, bound space, dissolution, and mineralization were introduced. And the effects of temperature, pressure, reservoir heterogeneity and formation water salinity on various forms of CO 2 storage were summarized. Furthermore, the research methods of CO 2 injection technique through molecular simulation, physical simulation, mathematical model, and reservoir numerical simulation were introduced. Finally, the reasonable prospect of CO 2 injection technique for shale oil reservoirs was proposed based on the current technical problems. The purpose of this paper is to provide a theoretical basis for EOR and carbon geological storage of shale reservoirs by using the CO 2 injection technique. [Display omitted] • Reservoir and fluid properties of major shale oil reservoirs were summarized. • EOR mechanisms of CO2 injection in shale reservoirs were reviewed systematically. • Research methods of CO2 injection techniques in shale reservoirs were introduced. • Future perspectives of CO 2 injection techniques in shale reservoirs were analyzed. [ABSTRACT FROM AUTHOR]

Coal-based chemical looping gasification (CCLG) has been proposed as an emergent type of coal gasification technology that produces high-quality syngas by using lattice oxygen from oxygen carrier instead of molecular oxygen. In this paper, the Fe–Ni composite oxygen carrier was synthetized using sol-gel method and the gasification performance of the prepared sample was analyzed by a fixed-bed reactor. The results indicated that the Fe–Ni composite oxygen carrier presented a high carbon conversion of fuel and syngas selectivity during the CCLG process. Additionally, the cycle stability test showed that the carbon conversion of fuel and syngas selectivity did not change significantly with the increase of cyclic frequency. To further study the influence of volatiles released from coal on the gasification performance of oxygen carrier, the interactions between the oxygen carrier samples and char obtained at different pyrolysis temperatures were investigated by a fixed-bed reactor and TG-MS, respectively. The results suggested that the gas products (H 2 , CO, CO 2 and CH 4) yields of char-oxygen carrier were significantly lower than those of coal-oxygen carrier. Besides, the pyrolysis temperature for preparing char had a great effect on the carbon conversion of fuel and syngas selectivity due to the distinction of volatiles released from solid fuel. • Efficient Fe–Ni composite oxygen carrier was crafted via sol-gel method. • Fe–Ni composite oxygen carrier showed good performance with desirable reactivity and cyclic stability. • Interaction between oxygen carrier and volatiles released from coal was investigated. • Char gasification was demonstrated to be the rate determining step during the CCLG process. [ABSTRACT FROM AUTHOR]

The sintering temperature of an oxide/oxide composite, comprising a barium aluminosilicate (BaAl 2 Si 2 O 8 or BAS) matrix reinforced with alumina fibers, is constrained to avoid a decrease in the mechanical properties of the fibers. This paper highlights the potential of sintering additives in lowering the sintering temperature of the hexagonal BAS (hexacelsian), thereby safeguarding the integrity of the fibers. Consequently, the role of sintering additives, MgO, TiO 2 , and B 2 O 3 , is investigated to determine their impact on the BAS matrix sintering. The addition of 1 wt% of these additives successfully achieved this objective, as confirmed through thermal and microstructural analyses. MgO and TiO 2 facilitated sintering kinetics through a solid-phase mechanism. Concerning the addition of B 2 O 3 , its effect on BAS sintering accelerated densification through a transient liquid-phase mechanism. Another consequence of incorporating these sintering additives is the destabilization of the hexagonal BAS. To limit this phenomenon, the addition of 1 wt% Rb 2 CO 3 served as a stabilizer through steric hindrance, partially substituting the Ba element in the BAS matrix with Rb. [ABSTRACT FROM AUTHOR]

Rising levels of carbon dioxide (CO 2) emissions due to human activities exert a substantial adverse effect on the environment. The conversion of CO 2 into methanol (CH 3 OH) through hydrogenation is a promising way to utilize this greenhouse gas, thus maintaining carbon in the cycle. In terms of sustainability, methanol is of particular interest because of its dual utilization potential as a fuel or base material to produce different chemicals. The versatility of the latter allows it to be used directly as a precursor to produce numerous compounds, including dimethyl ether (DME), olefins, formaldehydes, and hydrocarbon fuels. This paper first reviews the latest developments in catalyst design, focusing on the relationship between catalyst structure and performance. In addition, recent advances in understanding the reaction mechanisms, optimizing catalyst architectures, innovating membrane reactors, and reaction conditions have been discussed. This summarizes the strategies for increasing the efficiency of sustainable methanol production with the help of membranes. This study provides an outlook for future research in this field. [Display omitted] • Developing efficient hydrogen conversion is essential for addressing climate change. • Technological improvements in the synthesis of water selective zeolite membranes. • Latest developments in CO 2 hydrogenation using Cu-based catalysts. • Adapting zeolite membranes in catalytic membrane reactors to increase methanol yield. • Challenges and perspectives of CO 2 hydrogenation in the presence of a membrane. [ABSTRACT FROM AUTHOR]

Decarbonizing the building sector to achieve sustainable development goals (SDGs) is a complex issue that poses significant challenges to the scientific community. In this context, the current paper aims to assess the viability of employing incinerated by-products as a sustainable mineral resource to produce sustainable geopolymers. To this end, the study focuses on the formulation of geopolymer binders using fly ash with various proportions (ranging from 0 % to 50 %) of metakaolin (MK), investigating their physico-mechanical, microstructural analysis as well as their sealing capacity. The results indicate that incorporating 30 % MK not only preserves good workability but also significantly improves mechanical strength, ensuring long-term durability by increasing bulk density and concurrently reducing water absorption and harmful porosity. Moreover, the results of the Toxicity Characteristic Leaching Procedure (TCLP) demonstrated that the released contaminants remained within the regulatory limits established by the USEPA. The geopolymer binder developed exhibited a significant reduction of 77.23 % and 57.92 % in terms of carbon dioxide equivalent (CO 2 -e) emissions and energy demand compared to conventional cement. This study introduces a novel approach to promoting a circular economy within the building sector. [Display omitted] [ABSTRACT FROM AUTHOR]

In order to guide the operation of the actual cascade system, this paper takes the cascade system as the research object and compares the use of six refrigerant pairs. Unlike the previous single-objective optimization of refrigeration system carbon emissions and other indicators, this research uses a multi-objective optimization algorithm, that is, we consider the cascade system's exergy efficiency and carbon emissions at the same time. We reduce carbon emissions while improving the system's exergy efficiency, and finally find out the specific operating conditions under which the system can realize low-carbon and high-efficiency operation, which further promotes the process of achieving energy saving and emission reduction in factories. The optimization results show that among the six refrigerant pairs, the use of R744-R134a and R744-R290 refrigerant pairs can make the system operate better, but considering the high global warming potential (GWP) of R134a refrigerant, the use of R744-R290 combination is more recommended. [Display omitted] [ABSTRACT FROM AUTHOR]

To reveal the deflagration hazard and propagation law of hydrogen-enriched natural gas (H 2 NG) in closed spaces, this paper studied the deflagration characteristic parameters under different H 2 blended ratio (λ) and inert gas dilution fraction (X dilution) in slender closed pipelines with steel circular hole obstacles. The results indicate that the positive feedback mechanism's sustained effect, failure, and re-action leads to a "three-zone" distribution of H 2 NG explosion overpressure along the pipeline, namely the acceleration, attenuation, and rebound zones. The maximum explosion overpressure (P max), maximum pressure rise rate ((dP/dt) max), and peak shock wave propagation velocity (V p) all increase with the increase of λ. The rise of λ has the most significant enhancement effect on (dP/dt) max , while the enhancement effect on V p is the smallest. This is because the main reasons affecting their increase are different. P max , (dP/dt) max , and V p exhibit exponential decay with increased N 2 and CO 2. However, CO 2 has a more significant inhibitory effect on the H 2 NG deflagration process. When X CO2 = 25% and X CO2 = 30%, the deflagration process of H 2 NG with λ = 20% and λ = 80% can be inhibited entirely, respectively, which has important guiding significance for the safe application of H 2 NG. • The evolution law of deflagration shock waves in slender closed pipelines by H 2 NG was researched. • Effects of H 2 blended ratio and N 2 /CO 2 dilution fraction on H 2 NG deflagration characteristics were revealed. • The effects of N 2 /CO 2 dilution fraction on the P max , (dP/dt) max , and V p were predicted by an exponential model. [ABSTRACT FROM AUTHOR]

This paper presents and analyzes a finite volume scheme for a fully degenerate parabolic system modeling the compressible two-phase flow, such as water-gas, problem in porous media considering the effects of temperature. The problem is written in terms of the phase formulation, i.e. the saturation of one phase, the pressure of the second phase and the temperature are primary unknowns. We use a first-order time implicit Euler scheme. The spatial discretization uses a fully coupled fully implicit cell-centered two-point flux approximation scheme where upwinding of the flux across an interface between two control volumes is performed for each fluid phase. Under physically relevant assumptions on the data, we prove the maximum principle for both saturation and temperature. We obtain a priori estimates and we show that the discrete problem is well posed. Also, we exploit various a priori estimates as well as compactness arguments to establish the convergence of the numerical scheme toward the weak solution. The open-source platform DuMu X was employed for the implementation of the developed algorithm based on the above scheme. Numerical result are presented to demonstrate the efficiency of this scheme. The test addresses the evolution in 2D of CO 2 injection into a layered aquifer. The algorithm's convergence with first order is validated by our numerical results, which support the theoretical results. To our best knowledge, this is the first convergence result of a finite volume scheme in the case of nonisothermal immiscible compressible two-phase flow in porous media. [ABSTRACT FROM AUTHOR]

Chemical equilibrium represents the highest efficiency achievable by a thermochemical cycle under specific operational conditions. This study delves into two-step thermochemical water splitting cycles, which dissociate water into hydrogen (H 2) and oxygen (O 2) via sequential thermal reduction and re-oxidation processes. Building on the thermal reduction analysis presented in Part 1, this paper zeroes in on the re-oxidation reaction within the optimal reactor framework – the counter-current reactor. It elucidates the equilibrium pathway, delineating the progression of chemical equilibrium at each incremental stage of re-oxidation. Using ceria (CeO 2) as a model redox-active metal oxide, the investigation analyzes the influence of operational parameters on the re-oxidation reaction. Findings reveal the theoretical feasibility of maintaining near constant temperature (±2.5 °C) during re-oxidation, achieving a total extent of reduction of 0.038 and a hydrogen conversion yield of 32%. While near adiabatic operation is also achievable, practicality is constrained by a maximum total extent of reduction of 6.5·10−3. The study also explores the economic implications of thermochemical water splitting, particularly focusing on the steam-to-hydrogen output ratio. It highlights the severe economic hurdles associated with hydrogen yields below approximately 1%. Furthermore, the investigation reveals that the addition of inert gas to the re-oxidation step offers no significant advantages. Concluding the analysis, a comparative assessment exposes negligible differences in outcomes when substituting carbon dioxide (CO 2) for water (H 2 O) as the oxidant in low-temperature scenarios (800 °C). This comprehensive study not only advances the understanding of re-oxidation dynamics in thermochemical water splitting but also informs practical and economic considerations crucial for the advancement of this technology. • Reversible/equilibrium re-oxidation pathway defined for water splitting cycles. • Reversible quasi-constant temperature and quasi-adiabatic re-oxidation is feasible. • Limited impact of gas purity on re-oxidation at fixed flow/minimum temperature. • Inert gas addition offers no thermodynamic advantage in re-oxidation. • Low re-oxidation temperatures expand the solution space for high cycle efficiency. [ABSTRACT FROM AUTHOR]

Syngas, which is used as both a fuel and a raw material, presents numerous safety risks during its utilization. In this paper, the effects of H 2 /CO ratio (R = 0%, 30%, 50%, 70% and 100%) and CO 2 dilution ([CO 2 ] = 0%–20%) on the explosion behaviors of syngas/air mixtures with different equivalence ratios (φ = 0.8, 1.0, 1.6, and 2.5) are examined via experiments and numerical calculations. The results show that the peaks of explosion pressure and OH* spectral intensity are significantly influenced by the H 2 percentage in the syngas. The introduction of CO 2 notably decreases these parameters in oxygen-rich and severe oxygen-poor states. Additionally, the flame propagation speed noticeably increases with increasing H 2 proportion in the syngas. The influence of CO 2 on the buoyancy instability of the spherical flame of syngas is considered negligible when compared to that of other combustible gases, such as CH 4. Nevertheless, the presence of CO 2 decreases the density ratio between the unburned gas and burned gas and increases the flame thickness of syngas/air mixtures. This trend reduces the cellular instability of the spherical flame, particularly in severe oxygen-poor states. Notably, there is a definite correlation between the formation of cellular flames and the rise rate of explosion pressure. The cellular structure on the flame surface becomes more pronounced when the rise rate of explosion pressure increases. Conversely, it develops later or is noticeably inhibited. Furthermore, the main reaction pathways are H 2 → ∙OH → H 2 O 2 → H 2 O and H 2 → ∙OH → CO → CO 2 during the syngas explosion process. ∙OH is critical in the entire chain reaction because it promotes the conversion of H 2 to H 2 O and acts as a vital connection between the reactants H 2 and CO in the explosion process. • The P max and I max were investigated with H 2 addition and CO 2 dilution. • The cellular instability of the spherical flame was analyzed. • The interaction of flame development and explosion pressure was revealed. • The main reaction pathways during the syngas explosion process were examined. [ABSTRACT FROM AUTHOR]

Legislation regulating the sustainability requirements for hydrogen technologies relies more and more on life cycle assessments (LCAs). Due to different scopes and development processes, different pieces of EU legislation refer to different LCA methodologies, with differences in the way multifunctional processes (i.e., co-productions, recycling, and energy recovery) are treated. These inconsistencies arise because incentive mechanisms are not standardized across sectors, even though the end product, hydrogen, remains the same. The goal of this paper is to compare the life-cycle greenhouse gas (GHG) emissions of hydrogen from four production pathways depending on the multifunctional approach prescribed by the different EU policies (e.g., using substitution or allocation). The study reveals a large variation in the LCA results. For instance, the life-cycle GHG emissions of hydrogen co-produced with methanol is found to vary from 1 kg CO 2 -equivalent/kg H 2 (when mass allocation is considered) to 11 kg CO 2 -equivalent/kg H 2 (when economic allocation is used). These inconsistencies could affect the market (e.g., hydrogen from a certain pathway could be considered sustainable or unsustainable depending on the approach) and the environment (e.g., pathways that do not lead to a global emission reduction could be promoted). To mitigate these potential negative effects, we urge for harmonized and strict guidelines to assess the life-cycle GHG emissions of hydrogen technologies in an EU policy context. Harmonization should cover international policies too, to avoid the same risks when hydrogen will be traded based on its GHG emissions. The appropriate methodological approach for each production pathway should be chosen by policymakers in collaboration with the LCA community and stakeholders from the industry based on the potential market and environmental consequences of such choice. • LCA methodologies for hydrogen-related policies are currently not fully harmonized. • Four hydrogen production pathways involving multifunctionality were analysed. • GHG emissions of hydrogen vary significantly with the LCA methodology adopted. • Inconsistencies can lead to market distortions, inefficiencies, and confusion. • There is an urgent need for harmonized and strict LCA guidelines for H2 production. [ABSTRACT FROM AUTHOR]

In this work, a detailed dataset containing 4051 data points gathered from 527 distinct experiments in 100 published articles for catalytic CO 2 methanation was analyzed using machine learning methods. A pre-analysis of the database was performed using simple descriptive statistics while a random forest (RF) model was developed to predict CO 2 conversion as the function of 23 descriptors including catalyst properties, preparation methods, and reaction conditions. Boruta analysis was also performed to identify the significant variables. The random forest model was found to be quite successful in predicting CO 2 conversion with the training and testing root mean square error (RMSE) of 6.4 and 12.7 respectively; R2 was 0.97 for training while it was 0.85 for testing. The success of the model was also verified by computing CO 2 conversion profiles for individual experiments in test data and comparing them with those reported in the related papers. [Display omitted] • Catalytic CO 2 methanation was studied using machine learning. • Dataset contained 4051 data points from 100 published paper. • Simple descriptive statistics and random forest (RF) were used as tools. • RF successfully predicted CO 2 conversion profiles for the test cases. [ABSTRACT FROM AUTHOR]

• Electroreduction of CO 2 to formate was performed. • Electrooxidation of glucose to formate was performed. • A membrane electrode assembly system that combines CO 2 electroreduction with glucose electrooxidation was presented. • Coupling of CO 2 electroreduction of with glucose electrooxidation generated formate with high efficiency. Electrocatalytic reduction of CO 2 (CO 2 ER) coupled with the oxygen evolution reaction (OER) is an energy-intensive process that generates low-value oxygen, limiting its industrial application. To overcome this limitation, here we report a membrane electrode assembly (MEA) system that combines CO 2 ER with glucose electrooxidation (GEOR) to simultaneously produce formate using bismuth subcarbonate and carbon nanotube hybrid (BOC-CNT) and nickel cobalt oxide decorated on carbon fiber paper (NCO-CFP) as the cathode and anode catalysts, respectively. The BOC-CNT catalyst showed excellent electrocatalytic performance for CO 2 ER to formate, affording a high FE HCOO - of 97.9 % with current density of 360 mA cm−2 at −0.77 V vs. RHE (-580 mV overpotential), and the NCO-CFP catalyst achieved GEOR at 0.99 V (vs. RHE) with FE HCOO - >98 %. The coupled CO 2 ER//GEOR MEA exhibits a low onset cell voltage of 1.20 V and reaches ultrahigh apparent Faraday efficiency of formate (>190 %) in a wide range from 1.8 to 2.4 V, achieving ∼ 33.3 % energy savings compared to CO 2 ER//OER with a high formate yield of 0.92 mol g-1h−1 at 100 mA cm−2. Besides, all generated formate can be collected from the electrolyte on the anode side due to the spontaneous migration of formate under electric field, thus reducing cross-contamination from CO 2 and alkaline electrolytes. In addition, the coupled CO 2 ER//GEOR system exhibited good electrocatalytic stability for at least 32 h. This strategy provides an innovative and promising approach for the co-electrolytic transformation of biomass derivatives and CO 2 to formate. [ABSTRACT FROM AUTHOR]

The reverse water gas shift (RWGS) is of great significance to the resource utilization of CO 2. In this paper, based on the features of MoO 3 , the Mo-based catalysts doped with Ga, Ti and Ce were prepared, and the effects of oxygen vacancies and basic sites on the RWGS reaction were studied. When the volume ratio of H 2 and CO 2 is 1 : 1, the yield of CO can reach 26.66%. Because it exposes higher concentration of Ce sites and moderate alkaline active sites on the surface. When the proportion of H 2 in the reaction gas increases, the highest yield of CO can reach 54.53%, which is mainly attributed to a large number of oxygen vacancies on the surface of MoTi. This study can be used as a reference for the design of catalysts for RWGS reaction under different reaction conditions. A series of Mo-based catalysts were prepared, and the significance of oxygen vacancies and surface basic sites in RWGS reaction was explored, and a reference was provided for the study of similar catalytic materials under different reaction gas ratios. [Display omitted] • MoO 3 by doping transition metal has a good application prospect in RWGS reaction. • The yield of MoTi and MoCe is close to equilibrium in RWGS reaction. • High CO 2 concentration is good for MoTi with higher density oxygen vacancies. • High H 2 concentration is good for MoCe with higher density surface basic sites. [ABSTRACT FROM AUTHOR]

The rapid depletion of fossil fuels has become the worst scenario as most of the energy needed still depends on the use of fossil energy, oil, natural gas, and coal. The combustion of crude oil and coal has contributed to the major anthropogenic carbon dioxide (CO 2) gas in the atmosphere and has worsened climate change and global warming. Therefore, the abundant CO 2 in the surrounding has opened the door to many studies to convert CO 2 into the next generation of fuels and indirectly reduce the greenhouse effect. Transition metal dichalcogenides (TMDs) nanomaterials have appeared as a practical and reliable catalyst for CO 2 conversion to sustainable fuels under normal atmospheric conditions. Having fascinating electronic and catalytic properties, these earth-abundant element-based materials are being explored and developed for real-world application. This paper reviews the recent insight into the synthesis, properties and application of TMDs as catalysts in electrocatalysis, photocatalysis and thermal catalysis for CO 2 reduction and conversion. The role of type of sulfide (S), selenide (Se) and telluride (Te)-based TMDs in the production of various valuable products such as formate (HCO 2 −), formic acid (CH 2 O 2), methanol (CH 3 OH), and ethanol (CH 3 CH 2 OH), amongst others, will be discussed in detail. The possible reaction pathways and mechanisms and the relationship between tailoring the catalysts properties and CO 2 activation towards high CO 2 reduction and conversion efficiency will also be evaluated. • TMD catalysts have demonstrated promising performance in converting CO 2. • TMD catalyst can be used for electro-, photo- and thermal-catalytic CO 2 conversion. • The synthesis and characterization methods of TMD catalysts has been reviewed. • The different types of TMD catalysts and their potential have been investigated. • The mechanisms of all catalytic reactions have been examined. [ABSTRACT FROM AUTHOR]

Reduction in the consumption of operational (primary) energy and emissions of harmful gases has recently become the focus of attention of the civil engineering sector. In this context, there is also emphasized the energy consumption and emission production values associated with the whole life cycle of the construction materials used, which is referred to as "bundled energy consumption" and "bundled emissions". This paper analyses the energy performance certificates in combination with the SBToolCZ methodology. Sustainability Building Tool is a methodology designed to assess the sustainability of buildings. This methodology is used to assess the environmental impact of buildings at different stages of their life cycle, such as production, operation and demolition of the building. The amount of carbon dioxide and sulphur dioxide produced during the life cycle of buildings was determined by analysing and extending the building assessment data by the SBToolCZ methodology, which was subsequently valued and incorporated into the lifetime costs. The data from 17 case studies from the Czech environment were analysed. Taking these environmental impacts into account, valuing them and analysing the cash flows of investors and society shows the importance of paying increased attention to sustainable construction and reducing its negative impact on the environment and climate. Research data shows that 30% of the operating costs of buildings are the societal costs associated with CO 2,eqv. and SO 2,eqv. production. [ABSTRACT FROM AUTHOR]

The paper reports the development of Cu-doped NiCo 2 O 4 ternary inverse spinel oxides through microwave-assisted hydrothermal method as effective catalysts for alkaline hydrogen evolution reaction (HER). The effective and controlled doping of Cu to NiCo 2 O 4 lattice by the partial replacement of Ni2+/Ni3+ with Cu+/Cu2+ results in the fine-tuning of structural, morphological, and electronic characteristics, favourable for electrocatalytic HER. The study effectively correlates the influence of variation in the percentages of Cu-doping on the material properties and thereby the electrocatalytic characteristics. The experimental results indicate that Cu 0.10 Ni 0.90 Co 2 O 4 electrode having optimum Cu-doping (10%) as the best electrocatalyst with the lowest onset potential for hydrogen evolution (242.7 mV) and reduced overpotential (72.5 mV) values by following a Volmer – Heyrovsky mechanism during HER. The improvement in HER performance after Cu-doping is due to the generation of greater number of active sites and reduction in electronic band gap. The present work advantageously utilises the scope of microwave-assisted transition metal doping strategy to fine tune the physicochemical and electronic characteristics, favourable for electrocatalytic HER, and this may pave a new way for tuning the electrochemical properties of metal oxides for various applications. • Microwave-assisted hydrothermal synthesis is used effectively to develop Cu-doped NiCo 2 O 4. • Cu-doping to NiCo 2 O 4 lattice creates more oxygen vacancies and improves electronic conductivity. • Cu 0.10 Ni 0.90 Co 2 O 4 with 10% Cu-doping exhibits promising electrocatalytic activity towards HER. • Cu-doped NiCo 2 O 4 follows Volmer – Heyrovsky mechanism during alkaline HER. [ABSTRACT FROM AUTHOR]

The optimal discharge pressure is the essential factor affecting the operating performance of the transcritical CO 2 system. This paper presents a detailed study on the mechanism of the optimal discharge pressure from the perspective of fixed gas cooler outlet temperature and the heat transfer pinch point. The fixed gas cooler outlet temperature mainly analyzes the mechanism of the optimal discharge pressure from the enthalpy difference of isotherm in the supercritical region. The heat transfer pinch point mainly analyses the optimal discharge pressure at low inlet water temperatures, in which the subcritical region close to the critical point is considered. The effect of different parameters on optimal discharge pressure and system performance is discussed. The results indicate that the unique CO 2 physical properties and the pinch point in the gas cooler cause the optimal discharge pressure of the transcritical CO 2 system. The physical properties mainly affect the optimal discharge pressure at the high inlet water temperature, while the pinch point mainly affects the optimal discharge pressure at the low inlet water temperature. The inlet and outlet water temperatures are the most significant factors affecting the system's performance. [ABSTRACT FROM AUTHOR]

14°N on the Mid-Atlantic ridge (MAR) is one of only a few locations worldwide where volatile-saturated, geochemically enriched mid-ocean ridge basalts (E-MORBs) have been recovered. These basaltic glasses are so gas-rich that CO 2 -filled bubbles may "pop" when brought to the surface, due to the pressure and temperature change. Although these "popping rocks" have long been regarded as representative samples of un-degassed magmas sourced from the upper mantle, uncertainties regarding both their generation mechanism(s) and the potential effects of gas loss/accumulation processes have hampered unambiguous quantification of the upper mantle volatile element (water, carbon, nitrogen, noble gas) inventory. Fortunately, the extent and consequences of gas loss/accumulation processes can be tested by studying characteristic changes in volatile elements compositions, including 4He/40Ar* (where 40Ar* is 40Ar corrected for atmospheric contamination). To document the mechanism of popping rock generation and potential effects of degassing and gas accumulation processes on MORB volatile systematics, we present a comprehensive volatile characterization (carbon, nitrogen and noble gas systematics) of popping rocks and associated MORBs (n = 19) recently sampled at 14°N on the MAR, including 2 normal MORBs (N-MORB) from an oceanic core complex (OCC) and 17 E-MORBs. In line with previous studies, we find that PR exhibit the lowest 4He/40Ar* (1.08 ± 0.04) among all MORB samples, lower than the conventional mantle production ratio of 3 ± 1. Such low 4He/40Ar* could either (i) derive from accumulation of first-generated bubbles originating from open-system degassing of underlying magmas, or (ii) represent the actual upper mantle production ratio. We summarize the arguments in favor of each of these two scenarios (including the required accumulation times for radiogenic noble gases accumulation, the K/U and 232Th/238U of the upper mantle, popping rock vesicle size distributions, and physical considerations for vesicle growth and upwelling through a basaltic magma), and discuss their implications for the volatile composition of un-degassed magmas from the upper mantle. We find homogenous N isotope compositions (average δ15N of −4.49 ± 1.40 ‰ at 14°N) but variable δ13C (from −11 ‰ to −3.4 ‰), potentially compatible with the expectations for residual dissolved gas after Rayleigh fractionation. However, explaining the light δ13C signatures of PR via this process appears incompatible with any of the two scenarios proposed for explaining their low 4He/40Ar*, which would predict (i) 13C-enrichements and (ii) no fractionation relative to an initial composition at δ13C ∼ -5 ‰, respectively. After correction for solubility-controlled degassing fractionation and potential gas accumulation processes using 4He/40Ar* systematics, we find relatively homogeneous C/3He ((2.65 ± 0.51) × 109) but variable C/N (from 125 up to 4578), whose potential origins are discussed as part of a companion paper (Part B: Source effects). [ABSTRACT FROM AUTHOR]

It is well known that solving the greenhouse effect caused by increasing CO 2 emissions is urgent, and CO 2 methanation reaction is a popular research area as one of the effective ways. However, there are great obstacles and challenges to develop catalysts with higher stability and catalytic activity. In order to reduce the activation energy required for methanation reactions, it is expected to introduce another metal into monometallic catalysts to form bimetallic catalysts through the synergistic effect between the bimetallic phases. This paper reviews the advantages of metal-phase combinations for bimetallic catalysts applied to CO 2 methanation. The main synthetic methods used to prepare bimetallic catalysts in recent years are discussed. The effects of bimetallic phase synergy, bimetallic phase structure, metal particle size and dispersion, metal component ratio, and carrier effect on catalyst performance are analyzed. Finally, the challenges and application prospects of bimetallic catalysts for CO 2 methanation are presented. • Hydrogenation mechanisms for combinations of combination of dual active components are analyzed. • The preparation method and auxiliary preparation technology of bimetallic catalyst are discussed. • The synergistic effect between the two metal phases should sometimes be enhanced and sometimes suppressed. • The structure between the two metal phases improves the efficiency of the catalysts. • Different catalyst particle sizes affect product generation in CO2 hydrogenation reactions. [ABSTRACT FROM AUTHOR]

The Chinese government has considered the transcritical CO 2 heat pump (TCHP) as a promising solution for space heating with the goal of "carbon peaking" and "carbon neutrality." Considering the convenient implementation and the performance improvement, the vapor injection technique should be taken into consideration. This paper presents the experimental and simulation investigation of the SCVI TCHP prototype with energetic and economic analysis. Under the design condition, the SCVI technique could improve the peak COP by 5.02 % with a 10.11 % improvement in heating capacity. Compared to the direct electric heater solution, the annual operation cost was reduced by 11966CNY, 29.03 % higher than the Base TCHP. The payback period was decreased from 8 to 6.9 years due to the application of vapor injection. The effect of ambient temperature on the system performances was evaluated based on the experimental data. As the simulation progressed, a control strategy optimizing both the discharge and the medium pressure was developed, and the influence of inlet and outlet water temperature was studied. [ABSTRACT FROM AUTHOR]

The interstage subcooling vapor-injection technique has been introduced to transcritical CO 2 heat pumps to alleviate performance degradation under conditions of low ambient temperature and high water-outlet temperature. This type of solution holds considerable appeal and finds utility across a wide range of applications. However, the efficacy and efficiency of such systems are contingent upon their management, which frequently requires the implementation of suitable control systems. The primary objective is to enhance the overall system operational performance, resulting in tangible advantages in terms of economic viability, energy conservation, and environmental sustainability. To achieve these objectives, one can utilize both explicit and implicit optimization methods ranging from Model Predictive Control (MPC) to Extremum Seeking Control (ESC), each with its strengths and weaknesses. This paper compares the performance of an ad hoc integrated MPC strategy and a multi-variable ESC one. Based on the results of the system operation employing the latter strategy, a significant linear correlation was discovered between the optimal medium pressure and the optimal discharge and suction pressure. Consequently, an intrinsic self-optimization strategy for the medium pressure was developed. Subsequently, a dynamic system identification was performed on the new system, incorporating this proposed strategy. To optimize the system Coefficient of Performance (COP) while maintaining the water outlet temperature, ensuring the thermal load constraint, the MPC strategy was employed. The main focus of the MPC was to determine the optimal Electronic Expansion Valve (EEV) opening degree and water pump settings. The integrated MPC strategy was evaluated and compared to the multi-variable ESC strategy under various conditions, including fixed design conditions, changing ambient conditions, and step-change water outlet temperature. The results clearly demonstrated the effectiveness and superiority of the integrated MPC. [ABSTRACT FROM AUTHOR]

• Validation and CO2 ejector simulation using HEM. • The only cross-sectional area parameter that affects the primary flow rate of a CO2 ejector is the nozzle throat cross-sectional area. • The nozzle throat and mixing chamber cross-sectional area have a significant effect on the secondary flow rate and entrainment ratio of the CO2 ejector. • The inlet cross-sectional area of the nozzle almost does not affect the secondary flow rate and entrainment ratio. • The pre-mixing chamber and the diffusion chamber outlet cross-sectional area do not have a significant effect within a certain range. In this paper, based on the homogeneous equilibrium model, the effects of nozzle inlet cross-sectional area, nozzle throat cross-sectional area, pre-mixing chamber cross-sectional area, mixing chamber cross-sectional area, and diffusion chamber outlet cross-sectional area on the performance of the ejector of a CO 2 transcritical refrigeration system are analyzed by using Ansys Fluent. The simulation results show that the primary flow rate of the ejector is sensitive only to the nozzle throat cross-sectional area, while the entrainment ratio is strongly influenced by the nozzle throat and the mixing chamber cross-sectional area, and there is an optimum value. The nozzle inlet cross-sectional area has no significant effect on the performance of the ejector. The pre-mixing and diffusion chamber outlet cross-sectional areas do not have a significant effect on the performance within a limited range, but deviating too much from the optimum value can also lead to degradation of ejector performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • A lab-on-strip device for direct evaluation antioxidant capacity of EVOO is proposed. • The device is composed of a laser nanodecorated sensor and a paper sampler. • The device is manufactured with office-grade materials and accessible instruments. • The device is portable and encloses all the analysis steps. • EVOO analysis occurs in 2 min and needs 4 µL of not pretreated sample. An electroanalytical lab-on-a-strip device for the direct extra-virgin olive oil (EVOO) antioxidant capacity evaluation is proposed. The lab-made device is composed of a CO 2 laser nanodecorated sensor combined with a cutter-plotter molded paper-strip designed for EVOOs sampling and extraction. Satisfactory performance towards the most representative o-diphenols of EVOOs i.e., hydroxytyrosol (HY) and oleuropein (OL) were achieved; good sensitivity (LOD HY = 2 µM; LOD OL = 0.6 µM), extended linear ranges (HY: 10–250 µM; OL: 2.5–50 µM) and outstanding reproducibility (RSD < 5%, n = 3) were obtained in rectified oil. The device was challenged for the extraction-free analysis of 15 different EVOO samples, with satisfactory recoveries (90–94%; RSD < 5%, n = 3) and correlation with classical photometric assays (r ≥ 0.91). The proposed device includes all analysis steps, needs 4 µL of sample, and returns reliable results in 2 min, resulting portable and usable with a smartphone. [ABSTRACT FROM AUTHOR]

[Display omitted] • Reconstructed Cu/Cu 2 O(X) (X = I, Br, and Cl) catalysts were prepared for CO 2 RR. • Cu/Cu 2 O(I) shows good catalytic performance with a FE of 58% for C 2+. • Reconstructed Cu+ and Cu0 species are primarily responsible for the activity. It is particularly desirable for the development of carbon utilization technologies to synthesize multicarbon products (C 2+) from the electrochemical CO 2 reduction reaction (CO 2 RR). In this work, Cu/Cu 2 O(X) catalysts (where X = I, Br, Cl) for selective electroreduction of CO 2 to C 2+ were reconstructed via cyclic voltammetry on carbon paper. The Faradaic efficiency (FE) for C 2+ (C 2 H 4 , C 2 H 5 OH, C 3 H 8 OH) production over Cu/Cu 2 O(Cl), Cu/Cu 2 O(Br) and Cu/Cu 2 O(I) reached 31%, 34% and 58%, respectively, at a potential of −0.76 V vs. the reversible hydrogen electrode (RHE). The Cu+ and Cu0 species obtained from the reconstruction of Cu/CuX are primarily responsible for the high C 2+ producing activity. [ABSTRACT FROM AUTHOR]

• Model for the analysis and design of CO 2 two-phase nozzles. • Statistical analysis of critical mass flow values. • Nozzle design for heat pump application. The pressing needs to increase efficiency in heat pumps require refined design of various system components. In common reverse cycles, the throttling valve performs pure energy dissipation, and therefore it is well suited to be replaced by technologies such as ejectors and turbines, to augment system performance. In both two-phase turbines and two-phase ejectors a supersonic convergent-divergent nozzle is commonly required, which is responsible for accelerating the refrigerant fluid from the high-pressure part (e.g. condenser) to the low pressure part (e.g. evaporator). In the design phase of these nozzles, the accurate prediction of the maximum mass flow rate, also known as the critical mass flow rate, is particularly complex due to the two-phase nature of the expansion. In this paper, a new statistical approach to determine the value of the critical mass flow rate for CO 2 , as refrigerant fluid, is presented and assessed. This approach is based on the MF (Massflow Factor) parameter, which well correlates the value of mass flow rate in sonic conditions. The relationship shown here is based on open experimental information and it is validated on data from the open literature and the industry. The relative error on critical flow rate is less than 15% in the validation range, placing this statistical approach at a level of accuracy comparable to other physical models. An example of design is provided in this paper to demonstrate the potential of the relationship found. This approach provides the designer with a straightforward and validated basis for a reliable preliminary design of expanding two-phase nozzles. [ABSTRACT FROM AUTHOR]