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Despite its activity, monometallic Ni-catalyst is highly susceptible to coke deposition and sintering in catalyzing dry reforming of methane (DRM). To counter these, a novel tremella-like monometallic Ni/SiO 2 catalyst was hydrothermally synthesized herein, realizing excellent activity, outstanding coke inhibition and robust structural stability for a durable DRM reaction. Functionality-speaking, the tapered ends of Ni-petals, sized at 8–15 nm, permit high DRM activity with suppressed coke formation while its thicker base spatially prevents Ni-sintering during high temperature reaction. Meanwhile, the open structure of catalyst resulting from such tremella-like structure also enhances the diffusion of reactants/products gas to/from catalytic surface, thus augmenting its activity for DRM. With merely 5 wt% Ni incorporated, CO 2 and CH 4 conversions of ∼90% could be attained with only ∼15% activity drop after 75 h of DRM. Full-restoration of activity could facilely be attained using 90 min in-situ oxidative regeneration. Mechanistic study coupling sorptive investigation, ex-situ XRD, and SEM reveals the pronounced adsorption tendency of CH 4 over those of CO 2 , H 2 and CO, confirming the adherence of DRM to Eley-Rideal reaction model in current study. Significantly, this study provides a new morphological-controlled strategy to conveniently impart excellent coke-inhibiting and sintering-resisting capability to monometallic Ni-catalyst. [Display omitted] • Tremella-like Ni/SiO 2 is highly active toward dry reforming of methane (DRM). • Tapered end of Ni-petal suppresses coke formation during DRM reaction. • Thick Ni base permits robust metal-support interaction for improved stability. • Open structure of Ni/SiO 2 improves the accessibility of reactants and products. [ABSTRACT FROM AUTHOR]

• N/K-doped TiO 2 modified with Ag NPs is synthesized by one-pot solvothermal method. • Impact of Ag loading on CO 2 photoreduction of N/K-doped TiO 2 is studied. • N/Kco-doping and Ag cocatalyst facilitate light harvesting and charge separation. • The N/K-TiO 2 -Ag nanospheres promote photocatalytic CO 2 reduction into CH 4. Solar-driven CO 2 reduction into hydrocarbon fuels has a great potential for mitigating the issues of greenhouse effect and fossil energy crisis we are currently facing. It is a great challenge for visible-light-driven photocatalytic CO 2 reduction into CH 4 with high selectivity and conversion efficiency. Herein, we report a synthesis of N/K-doped TiO 2 nanospheres with Ag nanoparticles decoration (N/K-TiO 2 -Ag) by a solvothermal method and study its photocatalytic CO 2 reduction performance. It is found that the N/K-TiO 2 -Ag composite exhibits superior photocatalytic CO 2 reduction into CH 4 yield and selectivity than K-TiO 2 and N/K-TiO 2. Indeed, the N/K-TiO 2 -Ag-0.5 sample shows the highest CH 4 yield with rate of 113.84 μmol g −1 h −1 and selectivity of CH 4 (93.71%) under light irradiation. The enhancement might be attributed to the synergy of N/K doping and silver loading. In particular, the N/K doping and the Ag cocatalysts introducing triggered improvement of solar energy utilization and charge separation as well as Ag-induced SPR effect and the K +-induced redistribution of photogenerated charge carriers cooperatively promotes photocatalytic CO 2 conversion into CH 4. It is expected this work would offer a guide for rational design of K/TiO 2 -based photocatalyst for selectively converting CO 2 into fuels. [Display omitted] [ABSTRACT FROM AUTHOR]

Copper is a mono-metallic catalyst to produce large amounts of hydrocarbons during the CO 2 electrochemical reduction reaction (CO 2 RR). Nevertheless, the high overpotential of the reaction process and the low selectivity of currently known catalysts for multi-carbon (or single) products still prevent this process from approaching commercialization. Here, we report the synthesis of different ratios of Cu/Co catalysts with multiple active centers treated with H 2 cold plasma. The resultant Cu 2 Co 1 catalyst showed a high current density of 20.7 mA cm−2 and a Faraday efficiency of 70 % for C 2 H 4. This Cu–Co bimetallic multi active center structure is conducive to the generation of *CO and further coupling to form C2 products, thereby improving the selectivity of C 2 H 4. This study provides a new way to design multi-active center tandem catalysts for the efficient production of C 2 H 4 products. [Display omitted] • The synergistic effect of Cu0, Co0 and Cu2+ affected the adsorption activation of CO 2 molecules during the CO 2 RR process. • The Cu 2 Co 1 electrocatalyst yields C 2 H 4 as major products with a FE of 70 % at −1.0 V vs. RHE and excellent durability (200 h). • This work represents a new method for design and preparation of Cu–Co multi-active centers tandem catalysts to enhance the C 2 H 4 FE in CO 2 RR. [ABSTRACT FROM AUTHOR]

Cofiring with reactive hydrocarbon and oxygenated fuels is an effective approach to enhance ammonia (NH 3) combustion, which raises growing interest in understanding C N interactions. Among these fuels, dimethyl ether (DME, CH 3 OCH 3) has attracted extensive attention due to its renewable nature and potential for large-scale synthesis from CO 2 feedstock. This work reports an experimental and modeling investigation on the laminar flame propagation of NH 3 and NH 3 /DME in O 2 /CO 2 atmosphere, with an emphasis on evaluating the enhanced NH 3 /CO 2 interactions under flame conditions. Laminar burning velocities (LBVs) were measured at elevated pressures up to 5 atm in a constant-volume combustion vessel. A kinetic model was developed and can well reproduce the measured LBVs in this work, as well as the LBVs and speciation data in literature. Modeling analyses and the modified fictitious diluent gas method were used to explore the effects of DME cofiring, pressure and CO 2 dilution on LBVs. The results reveal that the chemical effect plays a crucial role in promoting the laminar flame propagation of NH 3 with DME cofiring, while the reduction of LBVs with CO 2 dilution is predominantly influenced by the thermal effect. LBVs of NH 3 /DME present a stronger pressure dependency than that of pure NH 3 , which is attributed to the enhanced pressure-sensitive three-body reactions, including CH 3 + H (+M) = CH 4 (+M) and H + O 2 (+M) = HO 2 (+M). Phenomenological analysis of LBVs was conducted by varying the diluent gas from pure N 2 to pure CO 2 , complemented by modeling analyses with adjusted rate constants, to provide insights into NH 3 /CO 2 interactions. The results show that CO 2 reduction reactions, including NH + CO 2 = HNO + CO and CO + OH = CO 2 + H, compete for reactive radicals like H and NH with chain-branching reactions H + O 2 = OH + H and consequently prohibit the laminar flame propagation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel vacuum-thermal assisted hybridization strategy of MOF on COF is proposed. • Construction of a novel sunflower-like MOF@COF hybrid system with strong π-π bond stacking. • The photocatalytic pathway can be adjusted by regulating the ratio of MOF and COF. • Sacrificant-free photocatalytic CO 2 reduction for methane production with excellent activity. Metal-organic framework (MOF) and covalent organic framework (COF) hybrid materials have drawn much research attention in the field of photocatalysis due to their complementary advantages, massive specific area, customizable structure and performance, and suitable band gap. Herein, the MOF@COF hybrid platform with a novel sunflower-like strong π-π bond stacking was formed by introducing the preformed synthetic COF into the MOF precursor solution and modulating its morphology by vacuum thermal-assisted growth. More importantly, the synthesized MOF on the COF hybrid platform with multiple active centers exhibits excellent catalytic activity in the sacrificial agent-free photocatalytic CO 2 reduction reaction under simulated sunlight. Additionally, the maximum CH 4 yieldrate of the synthesized PCN-222-Cu@TpPa-1 (1:2) reached 21.27 μmol g-1h -1, with an AQY (apparent quantum yield) about 10.46 % (in pure water system, λ = 550 nm) and a methane selectivity of about 27.25 %. The best performance of PCN-222-Cu@TpPa-1 is approximately 4.3 times higher than that of pure PCN-222-Cu and 100 times higher than that of the reported NH 2 -MIL-125(Ti) NMB. The selectivity of the products CO and CH 4 can be improved by adjusting the ratio of MOF and COF. Finally, the goal of providing an optimal photocatalytic platform for increased photocatalytic CO 2 reduction with highly effective morphology-tunable MOF@COF was expanded upon by a potential photocatalytic reaction mechanism, which was suggested based on the analysis of experimental results. [ABSTRACT FROM AUTHOR]

• A novel asymmetric Pd 1 O 3 C 1 active site was conveniently constructed. • The Pd 1 O 3 C 1 site offers ultrahigh activity and durability in CO 2 electroreduction. • The Pd 1 O 3 C 1 -based tri-phase cathode exhibits high performance in Zn–CO 2 battery. Single-atom catalysts (SACs) have attracted great attention for electrocatalysis. The coordination configurations of heteroatoms surrounding the metal center have a significant influence on the catalytic performance. The construction of asymmetric coordination configurations has recently been found to be an efficient strategy to improve electrocatalytic performance. However, noble-metal-based SACs with an asymmetric coordination environment have seldom been achieved. Herein, we rationally design and construct single-atom Pd catalysts with asymmetric Pd 1 O 3 C 1 or Pd 1 N 3 C 1 sites anchored on oxidized mesoporous carbon with optimized porosity and hydrophobicity. The as-prepared catalyst (Pd1-O-CB) selectively produces CO with a high CO Faradaic efficiency (FE CO) of 99.6 % at a low potential of –0.6 V versus reversible hydrogen electrode (RHE). Furthermore, the Pd1-O-CB-based gas diffusion layer exhibits a high current density of 280.4 mA cm−2 and long-term stability over 48 h benefitted from the regulated porosity and hydrophobicity of the tri-interface. Finally, a rechargeable Zn–CO 2 battery is constructed with the optimal gas diffusion electrode to deliver a maximal power density of 1.72 mW cm−2. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hierarchical ZnO@ZnFe 2 O 4 \CdS cages were designed and fabricated. • Stepped band heterostructure accelerates charge transfer and separation. • Hierarchical hybrid possesses more active sites and enhanced visible-light absorption. • Hierarchical hybrid exhibits excellent photocatalytic CO 2 reduction activity. Converting CO 2 into chemical energy by efficient photocatalysts is a promising strategy to meet the increasing energy demand and decrease greenhouse gases. In this work, hierarchical ZnO@ZnFe 2 O 4 hollow polyhedrons decorated with CdS quantum dots were designed and prepared to improve photocatalytic CO 2 reduction performance. The facile strategy for the synthesis of hierarchical ZnO@ZnFe 2 O 4 hollow polyhedrons involves the synthesis of ZnO hollow polyhedrons derived from the thermal decomposition of 2-Methylimidazole zinc salt (ZIF-8) precursor and in situ generating Zn-Fe layer double hydroxide nanosheets on the surface of ZnO hollow polyhedrons and subsequent thermal treatment. More importantly, the in situ formation of ZnFe 2 O 4 nanosheets can form strong interaction between ZnO hollow polyhedrons and ZnFe 2 O 4 nanosheets. The hierarchical hollow polyhedral structure of the ZnO@ZnFe 2 O 4 sample possesses more preferable active sites to promote CO 2 adsorption and reduction process. The prepared hierarchical ZnO@ZnFe 2 O 4 hollow polyhedron sample shows a significantly enhanced performance for photocatalytic CO 2 reduction compared with single-component catalysts (ZnO, ZnFe 2 O 4 , and CdS) with a CO evolution rate of 95.84 μmol g−1h−1. The decoration of CdS quantum dots makes the ternary heterostructure hybrid form multichannel charge transfer path, which further accelerate charge separation and enhance electrons utilization, resulting in a significant improvement of photocatalytic activity. Noticeably, the CO evolution rate reaches 197.66 μmol g−1h−1, 3 and 2 times higher than that of the bare ZnO and binary ZnO@ZnFe 2 O 4 hollow polyhedrons, respectively. This work gives a promising direction to prepare high-active photocatalysts for solar fuel production. [ABSTRACT FROM AUTHOR]

[Display omitted] • The removal efficiency of SMX by Co@mZVI/PAA system was 2.4 times of mZVI/PAA system. • R-O• played an important role in SMX degradation in the first 10 min of the reaction. • •OH was primarily responsible for SMX removal in the following 10–30 min. • The Co loaded mZVI could accelerate mZVI corrosion with a result of higher generation of •OH. • The intermediate degradation products of SMX had no apparent toxicity. Developing a cost-effective, easy-recycled, pH-independent and efficient activator is promising for the practical application of peracetic acid (PAA) based advanced oxidation process (AOP). In this study, Co@mZVI was synthesized to activate PAA for successful degradation of 96% sulfamethoxazole (SMX) within 30 min, while only 40% of the SMX could be removed in the mZVI/PAA system. Co-doping of Co extended the pH tolerance of mZVI as indicated by 90%-98% SMX removal efficiency at the initial pH range of 3.0–9.0. Reactive oxidized species (ROS) includ i ng organic radicals, hydroxyl radical (•OH) and Fe(IV) were produced from the Co@mZVI/PAA system. It's found that the co-doped Co can 1) work as a catalyst to activate PAA with the generation of ROS dominated by CH 3 CO 2 • and CH 3 CO 3 • in the period of 0–10 min; 2) boost the production of iron ions by accelerating the corrosion of mZVI in the following 10–30 min, in which • OH played a main role in contaminant degradation. The eight intermediate degradation products of SMX resulted from the attack of •OH, CH 3 CO 2 • and CH 3 CO 3 • were detected and the possible degradation pathways were proposed. The biological acute toxicity of the Co@mZVI system during the treatment of SMX decreased over the reaction time. Additionally, Co@mZVI has good recovery ability and stability, suggesting the potential applicability of the Co@mZVI/PAA system in degrading antibiotics. [ABSTRACT FROM AUTHOR]

The highly ordered and designable properties of MOFs make them competitive precursors to constructing high-performance catalysts for CO 2 methanation, however, only a few studies have investigated the facilitation effect of promoters. Herein, a series of carbon encapsulated NiFe alloy nanoparticles core-shell catalysts (Ni x Fe@C, x refers to the ratio of Ni to Fe) were successfully prepared by a method of pyrolyzing Ni-MOF-74 after impregnation in Fe3+ solution for CO 2 hydrogenation to CH 4 , and their composition and structural characteristics were explored in detail by PXRD, N 2 adsorption/desorption measurements, TEM, and XPS, etc. Fe-doped catalysts exhibited significantly enhanced CO 2 methanation activity compared to the monometallic Ni catalysts, especially Ni 7 Fe@C, which reached 72.3 % CO 2 conversion with CH 4 selectivity of 99.3 % at 350 °C, and showed a CO 2 conversion of 53.3 % at 300 °C, twice that of Ni@C. The specific effects of the Fe addition on the composition and structure of the catalysts were also investigated via a combination of experiments and DFT calculations, which indicates that appropriate incorporation of Fe was conducive to promoting the dispersion of metal particles and the adsorption ability of CO 2 and CO, and thus resulted in significantly improved catalytic performance. This work provides a promising route for the rational design of MOF-derived CO 2 methanation catalysts and makes a new attempt to investigate the influence of promoters. [Display omitted] • Ni x Fe@C catalysts with evenly distributed NiFe alloy nanoparticles and core-shell structure were derived from Ni-MOF-74. • The addition of Fe significantly improved the catalytic performance of Ni@C catalyst. • Fe boosts methanation activity by promoting the dispersion of metal particles and the adsorption ability of CO 2 and CO. [ABSTRACT FROM AUTHOR]

• An ejector with a submerged nozzle is designed and investigated. • Pentamethylene diisocyanate is prepared in a JLR with high efficiency. • An optimal operation scheme for JLR is obtained. • Under the same operating condition, JLR is superior to a STR system. A highly efficient jet loop reactor (JLR) with a submerged nozzle was developed to enhance the mixing and dispersion capacity of a phosgenation reaction, which was implemented in the preparation of pentamethylene diisocyanate (PDI). Model test of air–water two-phase flow was carried out first, which provided references for the control conditions of the phosgenation of 1,5-pentanediamine (PDA). Carbon dioxide (CO 2) was used to protect PDA as 1,5-pentanediamine carbonate (PDAC). Both the carbonate-forming and phosgenation reactions were preferably carried out in the JLR. The phosgene inlet pressure, asynchronous speed of the circulating pump, PDI content, and reaction completion time in the JLR system were investigated. Interestingly, we found that the PDI content exceeded 0.6–0.7%, the yields of PDI exceeded 7–8.5%, and the reaction time was decreased by approximately 50% compared to that of the traditional stirred-tank reactor (STR). The JLR is thus applicable for the preparation of PDI and is superior to the STR system. [ABSTRACT FROM AUTHOR]

A bifunctional Co 3 O 4 -La 2 O 2 CO 3 /C material was successfully fabricated via calcinating Co and La metal organic frameworks (MOFs) at 500 °C and employed to activate peroxymonosulfate (PMS) for simultaneous degradation of phenylphosphonic acid (PPOA) and adsorption of the released phosphate. 100% degradation of PPOA (100 μmol L−1) was realized by PMS (1.2 mmol L−1) mediated with Co 3 O 4 -La 2 O 2 CO 3 /C (0.2 g L−1) at initial pH 7 within 60 min. Meanwhile, the produced phosphate was also completely removed. A series of characterization of the Co 3 O 4 -La 2 O 2 CO 3 /C material was conducted, and the main factors impacting PPOA degradation and phosphate adsorption were investigated. Co 3 O 4 -La 2 O 2 CO 3 /C also exhibited superb stability. During 4 cycles, the removal rates of PPOA and the produced phosphate maintained at approximately 100% and above 93%, respectively. The investigation of electron paramagnetic resonance and quenching tests revealed that sulfate radicals and hydroxyl radicals were reactive oxygen species and the former made the predominant contribution to the oxidation of PPOA. The possible degradation pathways of PPOA were further proposed by analyzing intermediates. This study not only offers a feasible strategy for the safe disposal of organophosphorus and the released phosphate, but also extends the development of MOFs for the preparation of functional materials. [Display omitted] • Difunctional Co 3 O 4 -La 2 O 2 CO 3 /C derived from MOFs was successfully constructed. • Simultaneous PPOA degradation and phosphate adsorption was achieved at pH 3 ~ 7. • Co 3 O 4 -La 2 O 2 CO 3 /C possessed superb stability and reusability. • SO 4 •− and •OH were responsible for PPOA degradation in Co 3 O 4 -La 2 O 2 CO 3 /C/ PMS system. [ABSTRACT FROM AUTHOR]

Elevated CO 2 concentrations can change the multi-level nutritional relationship of the ecosystem through the cascading effect of the food chain. To date, few studies have investigated the effects of elevated CO 2 concentration on the Araneae species through the tritrophic system. Hylyphantes graminicola (Araneae: Linyphiidae) is distributed widely in Asia and is a dominant predator in cotton fields. This study investigated chemical components in the food chain of cotton (Gossypium hirsutum) — cotton aphid (Aphis gossypii) — predator (H. graminicola) and compared the development, reproduction, and predation of H. graminicola under ambient (400 ppm) and elevated concentration of CO 2 (800 ppm). The results showed that the elevated CO 2 concentration increased the chemicals of cotton and cotton aphid, but it did not affect the nutrients, development, reproduction, and predation of the spider. However, the survival rate of the spider was significantly decreased in elevated CO 2. The results will further our understanding of the role of natural enemies in an environment with elevated CO 2 concentration. [Display omitted] • Few studies have investigated the effects of elevated CO 2 on the Araneae species. • Hylyphantes graminicola is an important natural enemy in cotton fields in Asia. • Elevated CO 2 did not affect its development, reproduction, and predation. • The survival rate of the spider was significantly decreased in elevated CO 2. [ABSTRACT FROM AUTHOR]

To enhance the CO 2 capture and energy storage performances of carbon foams, we prepared hierarchical porous graphene oxide/biomass-based carbon foams nanocomposites from liquefied larch sawdust via in situ polymerization, foaming and carbonization steps. [Display omitted] • A hierarchically porous graphene oxide/carbon foam (GCF) nanocomposite derived from biomass is reported. • GCF exhibit superior CO 2 capacities, selectivities and recyclabilities for CO 2 capture. • Ultramicropore is key factor in deciding CO 2 adsorption at 1 bar and 25 °C. • GCF possess high specific capacitances and superior capacitance retentions in the application of supercapacitors. The development of biomass-based carbon foams with hierarchical pore structures could lead to practical applications in CO 2 capture systems and supercapacitors. However, these materials typically exhibit inferior adsorption and electrochemical characteristics because their pore structures are damaged during processing. The present work synthesized hierarchical porous graphene oxide (GO)/biomass-based carbon foam (GCF) nanocomposites from liquefied larch sawdust using in situ polymerization, foaming and carbonization steps. The GO enhanced the thermal stability of the foam while preventing collapse of the pore structure. The resulting GCF nanocomposites possessed hierarchical pore structures with greater ultramicroporosity than the original CF, especially with regard to the number of pores with sizes from 0.50 to 0.80 nm. Micropores with diameters less than 0.60 and 0.80 nm were found to be the primary factors determining CO 2 adsorption at 0.15 and 1 bar, respectively, such that the GCF-0.2 (the addition of 0.2 wt%) exhibited the highest CO 2 capacity of 4.99 mmol g−1 at 0 °C and 1 bar. These materials also showed CO 2 /N 2 selectivity values up to 100.21, moderate heats of adsorption between 10.27 and 18.77 kJ mol−1 and good stabilities. The GCF-0.2 displayed a specific capacitance of 173.20 F g−1 at a current density of 1A g−1 in a 6 M KOH electrolyte and demostrated superior capacitance retention that could lead to applications in supercapacitors. [ABSTRACT FROM AUTHOR]

The dry reforming of glycerol (GDR) is one of the alternatives for syngas production by utilizing biodiesel byproduct glycerol and CO 2. The development of highly active and stable catalyst is significantly important to achieve GDR process, and the current work provides insights into Co and Fe-doping effects of mesoporous CeO 2 (CoFeCe) catalysts synthesized by the colloidal solution combustion method. The prepared catalysts presented the uniform mesoporous structure, the doping of Co and Fe metals resulted in stronger metal-support interaction. The GDR experimental data were compared with the non-stoichiometric thermodynamic equilibrium values. The conversions of glycerol and CO 2 were increased with increasing the reaction temperatures due to the endothermic GDR reaction, and the H 2 /CO produced in syngas was in the range of 0.7–1.4. Due to the improvement of Co and Fe metals in the mesoporous structure of CeO 2 catalyst, the 7CoFeCe catalyst exhibited excellent and stable GDR performance and no significant signs of deactivation were observed during 76 h test, and the results indicated that the enhanced interaction and high dispersion of Co and Fe in mesoporous CeO 2 catalyst could inhibit carbon formation and promote GDR reaction. [Display omitted] • Co and Fe co-doping on CeO 2 catalyst enhanced GDR reactions. • Increasing in Co-doping improved conversions of glycerol and CO 2 to syngas. • Co–Fe interaction and CeO 2 redox ability inhibited the formation of carbon. • Catalyst with CoFeCe of mole ratio 7: 5:10 exhibited high activity and stability. [ABSTRACT FROM AUTHOR]

With the growing attention on both environmental and energy issues, the catalytic conversion of CO 2 has gained tremendous interest of researchers. Herein, we report a bimetal CoZn-ZIF derived highly efficient catalyst CoZn-Z for CO 2 methanation. After prereduction before the catalytic test, an inverse ZnO/Co structure with plentiful uniformly dispersed active sites could be formed, and the obtained CoZn-Z catalyst showed high Co dispersion with principally exposed Co (0002) lattice plane. Sufficient active sites, increased basicity and CO adsorption resulted in enhanced CO 2 methanation catalytic activity, and CO 2 conversion of 62.9 %, CH 4 selectivity of 99.2 % with a STY CH4 of 0.21 mol CH4 ·g cat. −1·h−1 were achieved at 300 °C, 2.6 times of monometallic Co-Z and exceeding most of the reported Co-based catalysts. Furthermore, based on in situ FTIR and DFT calculation, the formation of diverse reaction intermediates was studied and different dominant reaction pathways have been proposed for CoZn-Z and Co-Z. This investigation exhibited great potential of MOFs derived catalysts as superior CO 2 methanation catalysts and elucidates the promoting effect of ZnO in Co-based CO 2 methanation catalysts for the first time. [Display omitted] • CoZn-Z catalyst with ZnO/Co reverse structure and plentiful uniformly dispersed active sites was derived from CoZn-ZIF. • CoZn-Z showed a STY CH4 of 0.21 mol CH4 ·g cat. −1·h−1 at 300 °C, 2.6 times that of its monometallic counterpart. • The promoting effect and reaction pathway on ZnO promoted Co-based methanation catalyst were studied for the first time. • ZnO boosted methanation catalytic activity by improving the metal-dispersion, alkalinity and CO adsorption strength. • The introduction of ZnO changed the dominant reaction path of CO 2 methanation over Co-based catalyst. [ABSTRACT FROM AUTHOR]

Exploring highly-efficient and low-cost non-precious metal electrocatalysts for electrochemical reactions such as oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is of crucial importance for clean and renewable energy technologies. Herein, we report the synthesis of Co 2 P encapsulated in N- and O- co-doped carbons (Co 2 P@NOCs), which can serve as excellent noble metal-free bifunctional electrocatalysts for OER and ORR in alkaline media. Especially, the Co 2 P@NOC-2 electrocatalyst exhibits a low overpotential of 330 mV to deliver the current density of 10 mA cm−2 for OER in 1.0 M KOH solution, with a small Tafel slope of 97 mV dec−1. With respect to ORR activity, Co 2 P@NOC-2 gives positive onset (E onset) and half-wave (E 1/2) potentials of 0.90 and 0.75 V (vs. RHE) in 0.1 M KOH electrolyte, respectively. Additionally, it presents better methanol tolerance and long-term durability as compared to the commercial Pt/C (20 wt ·%) catalyst. The high electrocatalytic activity and good long-term stability toward OER and ORR can be attributed to the conductive heteroatoms-doped carbon layer, the embedded Co 2 P active sites and the synergistic effects between them. The strong synergism can significantly promote the electron transfer during the reaction and enhance the OER and ORR performance. Co 2 P encapsulated in N, O co-doped carbons (Co 2 P@NOCs) were successfully synthesized via pyrolysis of Co-containing polypyrrole (Co@PPY) precursors at high temperature and the subsequent phosphidation procedure. Thanks to the synergistic effect of the conductive heteroatoms-doped carbon layer and the embedded Co 2 P active sites, these noble metal-free materials have been proven to show remarkable performance toward both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in alkaline media with excellent durability. [Display omitted] • Co 2 P encapsulated in N- and O- co-doped carbons (Co 2 P@NOCs) were synthesized. • Co 2 P@NOCs can serve as bifunctional electrocatalysts for OER and ORR. • Active Co 2 P species and conductive carbon layer resulted in synergistic effect. • The synergism can promote the electron transfer and enhance catalytic performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • A highly dispersed CuO nano-island anchored Pt catalyst was designed and prepared. • Pt 0.5 -CuO 5 /HMS exhibited 100 % CO conversion (<0.2 ppb) at 110 °C in CO-PROX. • No inactivation was observed for Pt 0.5 -CuO 5 /HMS after 100 h of stability testing. • The adsorption and activation of CO tends to occur at the Pt-CuO interface. • The reaction energy barriers of H 2 on the Pt-CuO interface increased six times. In this paper, a highly dispersed CuO nano-island anchored Pt catalyst is designed and successfully prepared by selective electrostatic adsorption method. It is found that the nano-island catalyst exhibited excellent performance and stability in the CO preferential oxidation reaction. 100 % CO conversion and 50 % CO 2 selectivity are achieved at 110 °C and no indication of decreased efficiency is observed within 100 h. The CO 2 selectivity is constant over the entire temperature range. The characterizations and theoretical calculations are used to investigate the reaction mechanism. The results show that H 2 oxidation tend to occur at the upper surface of Pt clusters which are loaded on the CuO nano-island, whereas the CO oxidation tend to occur at the interface of Pt-CuO. Compared with Pt-Cu bimetallic catalyst, the interface structure of Pt-CuO has been proved to enhance the adsorption and activation of O 2 as well as reduce the energy barrier of CO oxidation from 0.28 eV to 0.01 eV. [ABSTRACT FROM AUTHOR]

[Display omitted] • A coupled chemical looping conversion of glycerol, CO 2 and H 2 O is achevied. • High-purity H 2 and syngas are one-step produced by GO, GDR and WS using OC. • Co-Fe interaction in OC inhibits the formation of carbon. • FeCoCe OC achieve excellent oxygen storage and redox reactions. • OC with 7:5:10 of Co: Fe: Ce presents high activity and stability. A coupled chemical looping conversion of glycerol and CO 2 with thermochemical water splitting (WS) cycle is substantially researched due to its potential for one-step renewable H 2 and syngas production. The major challenge lies on having good controls of redox reactions of the oxygen carriers (OCs) used and its unusual sensitivity to the changes of the compositions, chemical states and structure, etc. Here, we develop the OCs that consists of Fe 2 O 3 -Co 3 O 4 supported on the mesoporous CeO 2 structure (Fe 2 O 3 -Co 3 O 4 /CeO 2), which simultaneously promote glycerol oxidization (GO), dry reforming of glycerol (GDR), and WS processes. The easy migration and activation of lattice oxygen by Fe 2 O 3 -Co 3 O 4 /CeO 2 greatly improved the GO and GDR to produce syngas at the first step, and the pure H 2 production by the reduced Fe 2 O 3 -Co 3 O 4 /CeO 2 achieved excellent WS and oxygen storage at 750℃. The low-content Fe dopant in the OC presented a beneficial effect on the anti-sintering performance, and increase of Co-doping indicated a high activity to WS as well as enhanced GDR. The Fe 2 O 3 -Co 3 O 4 /CeO 2 with 7:5:10 of Co: Fe: Ce molar ratio presented the highest glycerol and CO 2 conversions and the highest H 2 yield, also illustrated the excellent activity and stability in 40 consecutive redox cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • The ILs biphasic absorbent [TEPAH][CPL]/EG/DGDE was developed for CO 2 capture. • Phase separation was due to polarity change of the absorbent after CO 2 absorption. • The regeneration energy consumption is 51% lower than that of 30 wt% MEA solution. • The absorbent showed obvious low-corrosive advantage since the absence of H+. To achieve low regeneration energy consumption and low corrosion, a novel ILs nonaqueous biphasic absorbents composed of Tetraethylenepentamine (TEPA) Caprolactam (CPL), Ethylene glycol (EG), and Diethylene glycol dimethyl ether (DGDE) have been proposed for CO 2 capture. The maximum CO 2 loading of the optimal absorbent ([TEPAH][CPL]/EG/DGDE) could reach 1.88 mol·mol−1, with 40 % of the saturated phase volume containing 98 % of the mass percentage of CO 2 products. Furthermore, the regeneration energy consumption was only 1.88 GJ·t−1 CO 2 , approximately 51 % lower than that of 30 wt% monoethanolamine (MEA) aqueous solution. 13C NMR analysis has shown that the amino group on the cation [TEPAH]+ reacted with CO 2 to form CO 2 products-carbamate, and the anion [CPL]- assisted the proton transfer during the reaction. Combined with the results from quantum chemical calculation, the phase separation behavior of the absorbent was mainly due to the polarity difference between the CO 2 products and the solvent. Additonally, [TEPAH][CPL]/EG/DGDE was non-corrosive to 20# carbon steel before and after CO 2 absorption, and exhibited superior stability than MEA aqueous solution. [ABSTRACT FROM AUTHOR]

• Adsorbed phase density and fugacity facilitate identifying the adsorption mechanisms. • SLD-PR model is efficient in obtaining adsorbed phase density at various pore sizes. • Excess adsorption isotherms are effectively rebuilt considering volumetric effects. • Absolute adsorption amounts are calculated accurately and reasonably considering PSD. • Empirical adsorbed densities for engineering practice are proposed through iteration. Understanding supercritical CO 2 (ScCO 2) adsorption behavior in nanoporous coals is crucial for long-term CO 2 geological storage. Four coal samples with a broad spectrum in rank were selected to obtain CO 2 excess adsorption isotherms at 35 ℃ and pressure up to 14 MPa using the volumetric method. As conversion from excess adsorption to absolute adsorption requires accurate capture of adsorbed phase density (APD), the simplified local density (SLD) theory and Peng-Robinson (PR) equation of state (EOS) were tailored to calculate the APD considering both pore size distribution (PSD) and pressure. Besides, volumetric effects, including void volume overestimation and coal matrix shrinkage/swelling, were quantificationally calibrated to reconstruct excess adsorption isotherms. Then, we proposed a novel conversion method based on real adsorption space distribution and adsorption mechanism. Results show that micropores in the range of 0.30–1.50 nm dominate the total pore space. APD and fugacity profiles reveal distinct CO 2 adsorption behaviors in micropores and mesopores. Fitted expansion coefficients indicate that coal matrix undergoes a superimposed effect of shrinkage and swelling during adsorption and the reconstructed isotherms could amend the large deviations around 8 MPa caused by the drastic changes of CO 2 bulk density and compressibility factor. Compared with conventional fixed APDs, the converted absolute adsorption isotherms generated by the varied ones exhibit slight fluctuations in the supercritical state and could plateau at high pressures. Continual iterations suggest that "averaged" APD in the range of 33–36 mol/L could be utilized for conversion in engineering practice only when the original excess adsorption isotherms are correctly reconstructed. [ABSTRACT FROM AUTHOR]

• MOFs derived difunctional Co 3 O 4 -La 2 O 2 CO 3 @C was successfully fabricated. • ROX was efficiently degraded by Co 3 O 4 -La 2 O 2 CO 3 @C activated PMS. • The generated arsenic was simultaneously adsorbed onto Co 3 O 4 -La 2 O 2 CO 3 @C. • Co 3 O 4 -La 2 O 2 CO 3 @C exhibited superior stability and reusability. • SO 4 − and OH were involved in the oxidation and transformation of ROX. In this study, a novel Co 3 O 4 -La 2 O 2 CO 3 @C composite was fabricated via the calcination of Co-La bimetallic MOFs at 500 °C, and was employed to efficiently activate peroxymonosulfate (PMS) for simultaneous oxidation of roxarsone (ROX) and adsorption of concomitant inorganic arsenic. Approximately 100% of ROX (50 μmol L−1) was degraded by PMS (0.5 mmol L−1) activated with Co 3 O 4 -La 2 O 2 CO 3 @C (0.2 g L−1) at initial pH 6 within 10 min. Meanwhile, the produced inorganic arsenic was almost completely adsorbed within 90 min. The maximum adsorption capacity of As(V) by Co 3 O 4 -La 2 O 2 CO 3 @C was determined to be high up to 275.4 mg g−1. Co 3 O 4 -La 2 O 2 CO 3 @C also exhibited superior stability. During 6 rounds, the degradation efficiency of ROX and the removal efficiency of the total As maintained almost 100% and more than 97%, respectively. SO 4 − and OH were confirmed to be the reactive oxygen species (ROS) in charge of the degradation of ROX and the conversion of As(III) to As(V). The investigation of the adsorption mechanism revealed that the As species were combined with La species via ligand and anion exchange, resulting in the formation of La-O-As bond. Furthermore, the practical application potential of Co 3 O 4 -La 2 O 2 CO 3 @C in the ROX degradation and the in-situ adsorption of the released arsenic were further evaluated in a continuous flow column reactor. The Co 3 O 4 -La 2 O 2 CO 3 @C composite as catalyst and adsorbent may offer a feasible strategy for the implementation of organoarsenic degradation and produced inorganic arsenic adsorption. [ABSTRACT FROM AUTHOR]

First, UV stopped-flow profiles were measured upon rapid mixing a series of soluble metal salt precursors with the Na 2 CO 3 solution to detect the kinetics of the complicated process involving the insoluble material formation reaction and the subsequent nanoparticles growth. Comparing the kinetic curves in 60 ms with 300 ms at 45–65 °C, it illustrates that the formation reaction of insoluble transition metal carbonates occurs rapidly (shorter than 60 ms) and precipitates as nanoparticles that act as the seeds for the subsequent particle growth. Then, a High-Shear co-Precipitation (HSP) method was developed to synthesize uniform LiNi 0.6 Co 0.2-x Mn 0.2 La x O 2 , overcoming the inherent difference of tens of magnitude in the solubility product constant (K sp) of individual carbonates. The synthesized LiNi 0.6 Co 0.198 Mn 0.2 La 0.002 O 2 exhibits an initial discharge capacity of 200.5 mAh g−1, superior to LiNi 0.6 Co 0.2 Mn 0.2 O 2 (194.7 mAh g−1, 0.1 C). In addition, the phosphorous coating of LiNi 0.6 Co 0.198 Mn 0.2 La 0.002 O 2 increased the capacity retention up to 86.4 % (400th, 5 C). DFT calculations indicate that La-intercalation can enlarge the Li+ layer spacing and reduce the Li+ migration energy barrier. This work illustrates the importance of the pulverization effects exerted by the High-Shear force on various insoluble nanoparticles during the initial rapid mixing period, providing a useful tool for manufacturing heteroatom-intercalated bulk nickel-rich cathode material. [Display omitted] • Insoluble carbonates nanoparticles are mixed evenly by ultrafast High-Shear force. • LiNi 0.6 Co 0.2-x Mn 0.2 La x O 2 is synthesized via a High-Shear co-Precipitation method. • LiNi 0.6 Co 0.198 Mn 0.2 La 0.002 O 2 shows an initial capacity of 200.5 mAh g−1 (0.1 C). • P-coating synergically improves the retention to 86.4 % (400th, 5 C). • La-intercalation enlarges the Li+ layer spacing of nickel-rich cathode. [ABSTRACT FROM AUTHOR]

Gas permeation in metal-organic framework-based (MOF-based) membranes is often elucidated through the solution-diffusion model, where the adsorption and diffusion of gases play equally vital roles. This study draws attention to a unique phenomenon known as single-file diffusion (SFD) occurring within MOF membranes that possess ultramicropores with dimensions comparable to the gas molecules themselves. When SFD takes place, the separation performance becomes solely reliant on the adsorption quantities on the feed side of the membrane. As a proof of concept, we fabricated a UTSA-280 membrane and subjected it to testing using gas mixtures of CO 2 /N 2 and CO 2 /CH 4. Two crucial observations substantiate the occurrence of single-file diffusion. Firstly, in the gas mixtures, the diffusion coefficients of N 2 or CH 4 were observed to align closely with that of CO 2 , despite the intrinsic diffusion coefficients of CO 2 , N 2 , and CH 4 , as determined from single-gas permeation experiments, exhibiting differences. Secondly, the CO 2 mole fractions within the adsorption phase closely mirrored those in the gas phase on the permeate side. Given the high adsorption selectivity of UTSA-280 for CO 2 , the UTSA-280 membrane delivers outstanding permeation selectivity for CO 2 /N 2 (611) and CO 2 /CH 4 (80.7). Our experimental findings are supported by mesoscale kinetic Monte Carlo simulations, which confirmed the relation between the CO 2 compositions in the adsorption phase on the feed side and in the gas phase on the permeate side. Furthermore, density functional theory calculations revealed high energy barriers associated with CO 2 surpassing its counterparts, rendering such processes unfavorable, thereby reinforcing our experimental findings regarding single-file diffusion. [Display omitted] • The UTSA-280 membrane is fabricated through interfacial growth. • The UTSA-280 membrane exhibits high CO 2 /N 2 selectivity (611) • The UTSA-280 membrane exhibits high CO 2 /CH 4 selectivity (80.7). • Single-file diffusion within the UTSA-280 membrane is investigated. • Single-file diffusion could make permeation selectivity governed by adsorption. [ABSTRACT FROM AUTHOR]

The Fe 3 O 4 -FeC x active site encapsulated by graphite shell was prepared and employed for converting CO 2 to light olefins successfully. The defects in the graphite shell in the core–shell structure formed by in-situ assembly are beneficial to the adsorption of CO 2 and the generation of light olefins. [Display omitted] • The Fe 3 O 4 -FeC x encapsulated by graphite shell was synthesized for CO 2 hydrogenation. • The obtained catalyst showed excellent activity in converting CO 2 to light olefins. • P123 could regulate the particle size and graphite shell thickness of catalyst. • The defects on graphite shell promoted the adsorption of CO 2 and olefins formation. • This work proposes a simple and feasible strategy to construct core–shell catalyst. Developing efficient catalytic materials and unveiling the active factors are significant for selective hydrogenation of CO 2 to light olefins (C 2–4 =). Herein, Fe 3 O 4 -FeC x nanoparticles coated by graphite without other doped elements were synthesized successfully. The optimal catalyst exhibited CO 2 conversion of 48.0%, C 2–4 = space–time yield of 29.0 mmol·g−1·h−1, and a stability of 100 h (3.0 MPa, 320 °C, and GHSV = 12000 mL·g−1·h−1). The core–shell structure derived from the strong interaction between the phenolic hydroxyl group of resin and iron ions, as well as the encapsulation of the copolymer P123. The characterization results revealed that the size of core–shell particles and thickness of graphite layers could be regulated by P123, which affected the conversion of CO 2 and products distribution significantly. Moreover, the combined results of quasi in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs) and Raman spectra suggested small particle size and thin graphite shell strengthen the adsorption and conversion of CO 2 , playing an important role in the formation of light olefins. This work proposes a simple and feasible synthesis strategy to construct Fe 3 O 4 -FeC x particles encapsulated by graphite shell, which provides insights into catalysts design and the reaction mechanism of CO 2 conversion to light olefins. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co-Fe/Al 2 O 3 was synthesized by the electroless plating-calcination method. • Co-Fe/Al 2 O 3 integrated high catalytic efficiency and low metal leaching. • OH• and SO•− 4 were identified as the predominant reactive species. • FeII promoted the regeneration of CoII to activate PMS. Peroxymonosulfate (PMS) based advanced oxidation processes are promising technologies for emerging contaminants removal and exploring catalysts with high catalytic activity and low metal leaching for PMS activation gets a lot of attention. Herein, Co-Fe/Al 2 O 3 was synthesized by electroless plating-calcination method. Characterizations indicated that Co and Fe were uniformly dispersed on the surface of Al 2 O 3. Results demonstrated that Co-Fe/Al 2 O 3 -PMS system could achieve 100 % sulfamethoxazole (SMX) removal with k obs of 0.0552 min−1 under optimal conditions of [PMS] = 0.20 mM, [Co-Fe/Al 2 O 3 ] = 50.0 mg/L, pH = 6.4. Compared with Co/Al 2 O 3 -PMS, Fe/Al 2 O 3 -PMS, Co-Fe/Al 2 O 3 alone, and PMS alone, the developed Co-Fe/Al 2 O 3 -PMS system achieved a combination of high decontamination efficiency, efficient PMS utilization and insignificant Co leaching. The electrochemistry tests proved the electron transfer speed of Co-Fe/Al 2 O 3 is much higher than that of Co/Al 2 O 3 and Fe/Al 2 O 3 , suggesting the synergistic effect of Co and Fe to enhance catalytic activity. The catalytic mechanisms were proposed that both CoII and FeII could react with PMS to initiate activation with SO 4 •- formation as the major active species and the coexistence of Fe and Co on Al 2 O 3 promoted the heterogeneous redox cycle of CoII/CoIII with CoII involving in PMS activation again. Furthermore, Cl− and H 2 PO 4 - facilitated SMX removal, while HCO 3 − and HA inhibited SMX removal. Co-Fe/Al 2 O 3 -PMS system could retain more than 80 % SMX removal within five cycles, indicating good stability and reusability of Co-Fe/Al 2 O 3 for PMS activation. Aniline ring oxidation and isoxazole ring oxidation were proposed as dominant degradation pathways according to the detected intermediates of SMX degradation. This research was instructive to the development of PMS activation induced by supported bimetallic catalysts for wastewater treatment. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO 2) assisted synthesis of water-soluble silver nanoparticle with a narrow particle size distribution is reported here based on the phase-inversion procedure. Bio-derived chitosan (CS) is used to stabilize the metal nanoparticles according to its abundant functional groups. Formic acid is employed as both a solvent (for the polymer) and a reductant for in-situ reducing the silver precursor along with the solvent evaporation. CO 2 is utilized to combine with the amino groups of CS, reducing the viscosity of chitosan/formic acid solution and limiting the formation of hydrogen bonds. This promotes the stabilization and reduction efficiency of silver nanoparticles. In particular, 100% of Ag metal nanoparticles with the size of 7.5 ± 2.3 nm is successfully synthesized with the assistance of CO 2. Interestingly, the synthesized CS/Ag nanocomposites are water-soluble owing to the formation of carbamate groups. This water-soluble silver nanoparticle presents an exceptional performance in the selective reduction of 4-nitrophenol, where the turnover frequency (TOF = 599 h−1) is even double with respect to the CO 2 free system. • CO 2 was used to reduce the viscosity of chitosan/formic acid solution, so as to limit the hydrogen bonds of the chitosan. • The carbon dioxide modified chitosan promotes the stabilization and reduction efficiency of silver nanoparticles. • The produced chitosan/silver nanocomposites are water soluble and present an exceptional catalytic performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • An amino acid ionic liquid [TEPAH][Pro]/NPA/H 2 O was proposed as a phase change adsorbent. • The absorption loading of [TEPAH][Pro]/NPA/H 2 O is 2.01 mol·mol−1, the rich phase viscosity is 8.06 mPa·s. • The efficiency of the 5th cycle of [TEPAH][Pro]/NPA/H 2 O was 80.1%. • The heat duty of [TEPAH][Pro]/NPA/H 2 O is 2.39 GJ·t CO 2 -1, which was 37% lower than that of 30 wt% MEA. • The CO 2 capturing reaction of [TEPAH][Pro]/NPA/H 2 O is a fast pseudo-first-order reaction. In order to overcome high heat duty and poor regeneration efficiency of existing chemical absorbent, a novel aqueous amino acid ionic liquids (AAILs) phase change absorbent with tetraethylenepentamine (TEPA) as cation, L-proline (L-Pro) as anion and N-propanol (NPA) as phase separator was proposed in this study. [TEPAH][Pro]/NPA/H 2 O owned the maximum absorption loading of 2.01 mol CO 2 ·mol absorbent−1, and the rich phase viscosity was only 8.06 mPa·s. Moreover, its desorption efficiency was 84.4% while the 5th cyclic loading kept above 1.61 mol CO 2 ·mol absorbent−1. With the presence of NPA, the rich phase only accounted for 41% of the total volume while it contained 99.3% of CO 2 products. The heat duty was only 2.39 GJ·t CO 2 -1, which was 37% lower than that of 30 wt% ethanolamine (MEA) aqueous solution. Meanwhile, the reaction mechanism and product distribution were revealed by 13C NMR and the mass transfer kinetics was investigated using the wetted wall column. The products in the rich phase mainly consisted of carbamate, hydrogen carbonate, propyl carbonate and water while the main component of the lean phase was NPA. The reaction followed a fast pseudo-first order reaction. At 313.15 K, the rate constant of fresh absorbent was 51346 s−1, which showed a decreasing trend with the increase of absorption loading at 313.15 K. The second order reaction rate was calculated by: k 2 = 9.88 × 109exp(-3591.2/T), where the reaction activation energy was only 29.86 kJ·mol−1. [ABSTRACT FROM AUTHOR]

[Display omitted] • CH 4 adsorption depends on C = C bond (major) and Cr, O atoms (secondary). • Cr, O atoms mainly influence CO 2 adsorption, C = C has a secondary impact. • Gas diffusion is influenced by pore size, molecular size, and the co-existence of another gas. • CH 4 prefers occupying large and medium cages, rarely entering the small cage. • CO 2 evenly distributes in medium, large cages, and small tetrahedron cages. An in-depth comprehension of the adsorption and diffusion properties of CH 4 , CO 2 , and their mixture in MIL-101(Cr) is crucial for its application in the highly selective separation of CO 2 and CH 4 mixtures in biogas. Existing studies often overlook the influence of gas molecular radius and MIL-101 topological structure on adsorption and lack quantitative analysis of the primary and secondary adsorption sites of MIL-101. Additionally, there is a significant gap in research on the adsorption mechanism of gas mixtures. To address these gaps and to provide new knowledge, this study employs Monte Carlo and molecular dynamics simulations to evaluate various factors such as CH 4 and CO 2 adsorption isotherms, density distribution profiles, self-diffusion coefficients, radial distribution functions (RDF), and CO 2 /CH 4 selectivity within MIL-101 metal-organic framework (MOF). The insightful and comprehensive atomic-level study reveals several unique and new findings, include 1) the RDF analysis shows that the C = C double bond of the benzene ring within MIL-101 primarily governs the adsorption of CH 4 , while the open metal center (Cr) exhibits significant adsorption effects on CO 2 ; 2) the density distribution profile analysis indicates that CH 4 molecules tend to localize in the larger and medium-sized cages, whereas CO 2 molecules exhibit relatively uniform distribution. 3) evaluation of self-diffusivity coefficients and diffusion activation energies demonstrated that CH 4 diffuses more easily than CO 2 , and in the CO 2 and CH 4 two-component gas, the existence of CH 4 can further reduce the diffusion coefficient of CO 2. This investigation provides a microscopic understanding of adsorption and diffusion phenomena within MIL-101, contributing to the overall comprehension of its behavior in gas separation applications. [ABSTRACT FROM AUTHOR]

• An interfacial Mo-S bond-bridged hierarchical S-scheme heterostructure is reported. • The Mo-S bonds can reinforce the separation and migration of photoinduced carriers. • The hierarchical heterostructure can benefit the CO 2 adsorption and activation. Developing highly-selective and efficient photocatalysts for converting CO 2 into carbon-based fuels by solar energy is desirable, whereas it is still a severe challenge. Herein, we present a unique interfacial Mo-S bond-bridged hierarchical S-scheme heterostructured photocatalysts, prepared by in-situ loading ZnIn 2 S 4 nanoflakes (ZIS-NFs) on the Bi 2 MoO 6 porous micro-spheres (BMO-PMs) assembled from numerous nanosheets. The interfacial Mo-S bonds can reinforce the separation and migration of photoinduced charge carriers via the S-scheme mechanism in the BMO@ZIS heterostructure. Besides, its hierarchical heterostructure can improve the visible-light response ability, and afford plenty of active sites so as to benefit the CO 2 adsorption and activation. Specifically, the combined results of experiment and density functional theory (DFT) calculations indicate that the fine heterostructure can not only convert the endoergic rate-determining step of bare ZIS (namely, CO 2 * hydrogenation to form COOH*) to an exoergic reaction process and lower the overall activation energy barrier, but also boost the desorption of CO* from the ZIS surface. As a result, in existence of H 2 O vapor without any sacrificial agents, the optimum photocatalyst (BMO@ZIS-0.4) manifests the outstanding CO 2 photoreduction activity, with a CO yield and selectivity of 23.11 μmol g−1h−1 and 93.1 %, respectively, higher than those of the most reported photocatalysts. This work offers an in-depth insight for fabricating the interfacial chemical bond-modulated hierarchical S-scheme heterostructure with a remarkable performance of CO 2 conversion. [ABSTRACT FROM AUTHOR]

The diagram vividly depicts the reduction of CO 2 to CH 4 on the active sites of TM@N 3 -VS 2. [Display omitted] • The novel SACs (TM@N 3 -VS 2) were designed based on the properties of VS 2 nanosheets with unique electronic structure, and the outstanding performance of nitrogen adjusting the coordination environment of transition metal for CO 2 RR. • The catalytic performance of TM@N 3 -VS 2 and TM@VS 2 for CO 2 RR was systematically compared and investigated. • TM@N 3 -VS 2 possess excellent performance for reduction of CO 2 to CH 4 , especially for Cr@N 3 -VS 2 with the lowest limiting potential of 0.2 eV. • The reason why N-doping leads to the excellent electrocatalytic CO 2 reduction activity was explained. The electrocatalytic reduction of CO 2 using single-atom catalysts (SACs) has significant potential to make a substantial impact on energy regeneration and greenhouse effect control in the future. The novel SACs were designed based on the properties of vanadium disulfide (VS 2) nanosheets with large surface area and unique electronic structure, and the outstanding catalytic performance of transition metal atoms bonding with nitrogen atoms for CO 2 reduction reaction (CO 2 RR). In this work, the electrocatalytic performance of N-doped vanadium disulfide nanosheets loading a series of transition metal single atoms for CO 2 RR was systemically evaluated by density functional theory (DFT). The results showed that TM@N 3 -VS 2 (TM = Ti, V, Cr, Mn, Zr, Nb, Mo, Ru, Rh) possess excellent performance for reduction of CO 2 to CH 4 , with low limiting potential of 0.36 eV, 0.28 eV, 0.2 eV, 0.34 eV, 0.54 eV, 0.33 eV, 0.55 eV, 0.38 eV, and 0.25 eV, respectively. The calculation results indicated that the nitrogen atoms could adjust the coordination environment of transition metal atoms and modulate the ability of transition metal atoms and VS 2 nanosheets accepting and donating electrons, which makes CO 2 adsorb on TM@N 3 -VS 2 with moderate adsorption energy, and significantly reduces the reaction energy barrier. [ABSTRACT FROM AUTHOR]

[Display omitted] • The AFIL [TEPAH][AICA]/NPA/EG was developed for CO 2 capture. • There were no HCO 3 - products in the absorption, so the corrosion rate of the saturated AFIL to carbon steel was very low. • The increase in absorption loading weakened the CO 2 absorbing ability of the AFILs, which led to the decrease in the K G. • The relationship between k 2 and temperature was expressed as k 2 = 7.2075 × 10 8 exp - 3093.5 T . Extensive energy consumption is a challenge for developing industrial carbon capture absorbents. A novel amino functionalized ionic liquid (AFIL) organic solution, tetraethylene pentamine 5-amino-4-imidazolecarboxamide/n-propanol/ethylene glycol ([TEPAH][AICA]/NPA/EG), is considered as a promising absorbent due to its high CO 2 absorption capacity and low energy consumption. However, its industry application potential still needs to be further evaluated for carbon capture process. In this work, thermodynamics, kinetics and corrosive behavior of [TEPAH][AICA]/NPA/EG solution were investigated. The regeneration energy consumption was 2.30 GJ⋅t−1 CO 2 , which was 39.5% lower than the benchmark monoethanolamine (MEA) solution. The mass transfer reaction kinetic model was established, showing that the reaction between CO 2 and [TEPAH][AICA]/NPA/EG solution followed fast pseudo-first-order. The enhancement factor and reaction rate constant increased with the increase of absorption temperature, while they showed a decreasing trend with the increase of absorption loading. The relationship between the second-order rate constant and temperature was expressed as k 2 = 7.2075 × 10 8 exp - 3093.5 T . The activation energy was 25.72 kJ·mol−1. During absorption process, the dominant mass transfer resistance gradually changed from gas phase to liquid phase. In addition, the absorbent presented non-corrosive behavior after saturated absorption, which was superior than the MEA absorbent for storage and transportation in the carbon capture technology. To be concluded, the above results showed that the [TEPAH][AICA]/NPA/EG solution owned great potential for future industrial application. [ABSTRACT FROM AUTHOR]

The continued warming of the Earth caused by CO 2 emissions and the limitations of current technologies have led to a demand for new green and non-polluting CO 2 capture technologies. Carbonic anhydrase (CA) mimicking nanozymes are a promising pathway for developing such technologies, but their incorporation of the spatial structure of natural active sites into nanomaterials remains a challenge. Therefore, the development of novel CA-mimicking nanozymes and the expansion of bionanomaterials for CO 2 capture technology are essential. In this work, a novel CA mimic using 2D nitrogen-doped graphene with Zn nanoclusters (Zn cluster /NG) was designed. Through changing the pyrolysis conditions, such as atmosphere and temperature, the enzyme-mimicking activities of Zn cluster /NG were rationally regulated. The regulation was ascribed to the fine tune surface properties and catalytic sites of Zn cluster /NG nanozymes such Zn nanocluster size, Zn content, and specific surface area, leading to the highest CA-mimicking activity possible by Zn cluster /NG-900–800NH 3. Notably, the Zn cluster /NG-900–800NH 3 nanozyme was capable of surviving high temperatures and wide pH ranges, and showed 10 times higher catalytic activity at 75 °C than at room temperature. Finally, experiments and DFT calculations were utilized to verify the advantages and surface catalysis mechanisms of Zn cluster /NG in CO 2 capture based on mimicking carbonic anhydrase. This study provides a facile and reference strategy for the rational design of CA mimics and broadens the application of nanozymes in CO 2 capture technology. [Display omitted] • A novel CA nanozyme using N-doped graphene with Zn nanoclusters (Zn cluster /NG). • Pyrolysis method allows fine-tuning of surface catalytic sites of Zn cluster /NG. • High-temperature stability of Zn cluster /NG shows potential for CO 2 capture. • Surface catalysis mechanism of Zn nanoclusters in CO 2 hydration calculated. • Study contributes to development of non-oxidoreductase nanozymes for CO 2 capture. [ABSTRACT FROM AUTHOR]

Fe-rich Sm 2 Co 17 -type magnets have many essential applications prospects in high-temperature operation environments. However, the formation of complete cellular microstructure becomes increasingly difficult when the Fe content of Sm 2 Co 17 -type magnets exceeds 20 wt%. Herein, the phase stability of 1:7 H phase and its effect on the precipitation of the 1:5 H precipitates in Fe-rich Sm 2 Co 17 -type magnets are investigated. The results confirm that the stability of the 1:7 H phase decreases with the increasing of Fe content for the solution-treated magnets. Not only 2:17 R phase but also a lot of 2:17 R′ phase is found in solution-treated magnets when the Fe content exceeds 22 wt%. As the Fe content increases, the density of initial defects decreases for the growth of 2:17 R nanotwins in the solution-treated magnets. Furthermore, the segregation of Cu in the defects-aggregated cell boundaries weakened gradually. Consequently, the nucleation and precipitation of cell boundary precipitates is difficult, and the cellular microstructure becomes incomplete and coarse when the Fe content is above 22 wt%. The present work may provide a further insight for understanding the evolution of cellular microstructure depending on the phase decomposition behavior in Fe-rich Sm 2 Co 17 -type magnets. • Various 2:17 R′ phases were found in solution-treated Sm 2 Co 17 -type magnet when the Fe content is above 22 wt%. • The ordering of 2:17 R phase during the solution treatment is not conducive to the segregation of elements. • According to XRD Rietveld analysis, the stability of 1:7 H phase decreases with the increase of Fe contents for the solution-treated magnet. [ABSTRACT FROM AUTHOR]

In this paper, the idea of Underground coal gasification coupled with supercritical carbon dioxide storage is proposed based on the problems of Underground coal gasification combustion area and carbon dioxide storage site, which provides a new technical approach for carbon peaking and carbon neutrality in the coal sector. At the same time, to solve the underground coal pillar design problem in the popularization and application of UCG-CCS, this paper adopts numerical simulation and theoretical analysis methods to reveal the deformation mechanism and bearing characteristics of "hyperbolic" type coal pillar in UCG-CCS. The results of this study are as follows: ① The injection of supercritical CO 2 into the underground goaf can effectively reduce the load of the coal pillar bearing the overlying strata and improve the bearing capacity of the "hyperbolic" protective coal pillar. ② The size of the "hyperbolic" coal pillar in UCG-CCS slightly influences the coal pillar's stability under certain injection pressure. For safety in practical engineering, it is necessary to ensure that the CO 2 injection pressure reaches its critical pressure of 7.38 MPa. ③ Based on numerical simulation results, when the width of the combustion cavity is 40 m, the width of the protective coal pillar is 56 m, the injection pressure of supercritical CO 2 is 7.38 MPa, and the sealing depth ranges from 800 m to 1200 m, the protective coal pillars are in a stable state due to the pressure effect of supercritical CO 2 on the coal pillar and the roof. The research results of this paper have important practical significance for promoting the site selection, product design, and application of UCG-CCS and provide a technical means for the coal industry to achieve carbon peak and carbon neutrality. [ABSTRACT FROM AUTHOR]

Under different concentrations of reagents, two coordination polymers were synthesized with different structures. In addition, 1 and 2 are further demonstrated to be high sensitivity and selectivity sensors towards Fe3+ ions through fluorescence quenching. [Display omitted] • Two 3D coordination polymers have been solvothermally synthesized and characterized under different concentrations of the solute. • 1 is a 2-fold interpenetrated pcu network at lower concentrations, but 2 is a 5-fold interpenetrated dia network at higher concentrations. • 1 and 2 have shown selectivity and sensitivity to Fe3+ through strong fluorescence quenching. The reactions of 1,2-bis(4-pyridyl)ethylene (bpe) and 2,5-furandicarboxylic acid (H 2 fdc) with Zinc(II) salts in different concentrations resulted in two new complexes, [Zn(fdc)(bpe)]∙DMF (1) and [Zn 4 (fdc) 4 (bpe) 4 (H 2 O) 2 ] ∙DMF·2H 2 O (2). At lower concentrations, 1 was formed, in which {Zn 2 (CO 2) 2 } can be seen as a 6-connected node, and the whole framework is a 2-fold interpenetrated pcu network. On the contrary, at higher concentrations, 2 was synthesized, in which all Zn2+ ions act as 4-connected nodes, and the whole framework is a 5-fold interpenetrated dia network. 1 and 2 are proven to be promising sensors towards Fe3+ ions with high sensitivity and selectivity through fluorescence quenching. [ABSTRACT FROM AUTHOR]

Excavating highly efficient M-N-C electrocatalysts for electrochemical CO 2 reduction (ECR) is of paramount importance. Herein, we report a single-atom Co-N-C catalyst (CoN 4 -CB) with a high CO Faradaic efficiency (FE CO , 98.7%) in ECR comparable to that of a similarly prepared NiN 4 -CB catalyst. Impressively, CoN 4 -CB demonstrates a CO turnover frequency of 27173 h−1 and a CO current density of −33.6 mA∙cm−2 at −0.76 V, 20.2 and 6.8 times higher than that of NiN 4 -CB, respectively. In a solar-driven ECR system composed of a Si solar cell and a flow cell, CoN 4 -CB shows a remarkably large current density of 98.3 mA∙cm−2 with an average FE CO of 92.1%. Theoretical calculations suggest that the energy barrier for *COOH formation largely decreases on CoN 4 sites compared with NiN 4 sites, leading to a low onset potential and high activity for CO production. This work will boost the development of efficient M-N-C electrocatalysts and further practical application of solar-driven ECR system. [Display omitted] • CoN 4 -CB catalyst enables efficient ECR to CO. • CoN 4 -CB displays comparable selectivity to NiN 4 -CB but much enhanced activity. • An optimized solar driven system for ECR to CO at high current density. • DFT results well supported the experimental results. [ABSTRACT FROM AUTHOR]

Bimetallic catalysts catalyst was potential catalyst for electrochemical reduction of CO 2 (CO 2 RR) to produce liquid fuel. Adjusting the adsorption energy of intermediates on bimetallic catalysts was very effective to improve the selectivity of electroreduction of CO 2 to low-carbon alcohols. However, it was difficult to further increase the yield of low-carbon alcohols by adjusting the content ratio between metals alone. Here, in vacuum environment, we use low temperature plasma technology to treat Ag@Cu catalyst to form Cu–CuO interface on the catalyst surface, so that the selectivity and activity of the reaction were further enhanced. The performance of CO 2 RR was effectively improved by the surface Cu–CuO interface. CO 2 RR tests show that at −0.8 V vs RHE, the faraday efficiency of low-carbon alcohols of Ag@Cu-10 catalyst was the highest of 65.5%, which was 19.9% higher than that of Ag@Cu. In addition, the linear sweep voltammetry test showed that the current density of CO 2 RR increased by 2 times, indicating that the surface Cu–CuO interface promoted the activation of CO 2 on the surface of the catalyst and improved the intrinsic activity. This work introduces a technique of preparing surface Cu–CuO interface to adjust the adsorption energy of CO 2 RR intermediates, which provides a new idea for the development of efficient CO 2 RR catalysts. • Surface Cu-CuO interface was prepared to improve the electrocatalytic activity of CO 2. • Ag@Cu exhibited excellent performance for CO 2 RR to low-carbon alcohols with FE of 65.5% at -0.8 V (vs. RHE) and current density of 13 mA·cm-2. • The synergistic effect of Ag and CuO promoted the adsorption of intermediate species. [ABSTRACT FROM AUTHOR]

• 15 tertiary amines with various structure were selected for quantum calculation. • Cyclic tertiary amine were more sensitive to protonation process than branched tertiary amines. • The phase separation rate is mainly effected by electronegativity. • The position of phase separation peak is determined by polarity. • The absorption rate is controlled by both polarity and electronegativity. Biphasic solvent has been widely studied for CO 2 capture due to its excellent energy-saving potentiality. However, its complex composition makes the prediction of main performances, like phase separation behavior or absorption rate, become obscure and difficult. This work investigated the relationship between the physical properties of tertiary amines and proton transfer process, phase separation behavior and absorption rate of biphasic solvents via quantum calculation and experimental results. The high electronegativity of tertiary amine N atom makes the biphasic solvent exhibit the fast phase separation rate and absorption rate, and maximum phase separation rate can reach 0.056 min−1. Furthermore, the increase of N atom polarity can delay the appearance of phase separation peak and stabilize the absorption rate during the counter-current absorption process. We believe that the relationship revealed by this work can deepen the understanding for screening and practical applying of biphasic solvents. [ABSTRACT FROM AUTHOR]

CO 2 foam fracturing fluid has the advantages of water saving and environmental protection, which has been widely used in unconventional oil and gas reservoir. However, there are still many technical difficulties in fracture propagation model and numerical calculation method of CO 2 foam fracturing. In this paper, a CO 2 foam fracturing fracture propagation model with temperature-pressure-phase coupling is established. Physical parameters of CO 2 are calculated by Span-Wagner method, and the finite difference and displacement discontinuity methods are used to solve the model. Moreover, we compare the results of this model with the field measured data, KGD model and EFRAC-3D model to verify the model. The computation results show that in the process of fracturing, improving the CO 2 foam quality can significantly enhance the fracturing effect. When the quality increased from 0.5 to 0.8, the fracture width raised by more than 2 times. In addition, the fracture propagation is significantly affected by injection temperature. With the increase of injection temperature, fracture width decreases continuously, and if the CO 2 foam is supercritical phase state, it is not conducive to increase the fracture width. • A CO 2 foam fracturing model with temperature - pressure - phase coupling is established. • Increasing the CO 2 foam quality can significantly improve the fracturing effect. • With the increase of the injection temperature of CO 2 foam fracturing fluid, the fracture width decreases continuously. • It is difficult for supercritical CO 2 to form a wider fracture. [ABSTRACT FROM AUTHOR]

Fe 3 O 4 -FeC x heterojunction active site confined in N-OMC was prepared and showed excellent activity in converting CO 2 to light olefins, which was attributed to the synergistic effect of heterojunction components in RWGS–FTS reaction. [Display omitted] • Fe 3 O 4 -FeC x heterojunction active site confined in N-OMC was prepared successfully. • The catalyst showed excellent activity and stable in converting CO 2 to light olefins. • The excellent activity was attributed to the synergy of Fe 3 O 4 -FeC x heterojunction. • The influence of N-OMC and K+ on catalytic activity and selectivity was explored. • Heterojunction was in favor of high yield of light olefins and low selectivity of C 1. Converting CO 2 into light olefins is full of challenges and opportunities, which was limited by poor activity catalysts. Herein, Fe 3 O 4 -FeC x heterojunction active site confined in N-doped graphene shell was synthesized on the surface of N-OMC. Alkali metal and N atom was used for modifying the surface electron density, which could suppress the excessive hydrogenation of CH x and improve the adsorption of CO 2 , thus increasing the yield of light olefins. The 0.8Fe-0.1K@N-OMC showed CO 2 conversion of 54.5%, C 2 =–C 4 = selectivity of 65.63%, and a stability of 100 h (3.0 MPa, 320 °C, and GHSV = 4800 mL/g cat /h). The reaction mechanism was investigated using various characterization techniques, which demonstrates that the excellent catalytic active was originated from Fe 3 O 4 -FeC x heterojunction. The CO was first produced by the RWGS reaction catalyzed by Fe 3 O 4 , and then converted to light olefins on the neighboring FeC x active site by FTs reaction. Confinement effect of N-doped graphene shell inhibits the reoxidation and agglomeration of heterojunction active components, which boosts the catalyst' stability. This work proposes a simple and feasible synthesis strategy to construct Fe 3 O 4 -FeC x heterojunction catalysts, which provides insights into catalysts design and the reaction mechanism of CO 2 conversion to light olefins. [ABSTRACT FROM AUTHOR]

Inspired by the exceptional mechanical and electrical properties of multi-walled carbon nanotubes, hierarchically porous multi-walled carbon nanotubes/biomass-based carbon foams nanocomposites with enhanced mechanical properties, CO 2 capture and electrical performances were prepared using liquefied larch sawdust as the carbon precursor, via in-situ polymerization, foaming and carbonization. [Display omitted] • A hierarchically porous multi-walled carbon nanotube/carbon foam (MCF) nanocomposite derived from biomass is reported. • Multi-walled carbon nanotubes enhance mechanical properties of biomass-based carbon foams. • MCF exhibit superior CO 2 capacities, selectivities and recyclabilities for CO 2 capture. • Micropores with pore diameters less than 0.80 nm are key factors in deciding CO 2 adsorption at 25 °C. • MCF possess high specific capacitances for supercapacitor electrode. Biomass-based carbon foams (CFs) exhibit improved performance relative to traditional porous carbons in many applications. However, the more extensive use of these materials is significantly impeded by their inferior mechanical properties, including poor compressive strength. In this work, we prepared hierarchically porous multi-walled carbon nanotubes (MWCNTs)/CF (MCF) nanocomposites using liquefied larch sawdust as the carbon precursor by in-situ polymerization, foaming and carbonization. MWCNTs incorporated in foam increased the compressive strength of the CF significantly (by 113%) and also improved the thermal stability and degree of graphitization. The MCF nanocomposites possessed more developed hierarchical porosities than the pure CF, in particular ultra-microporosity with pore sizes from 0.50 to 0.80 nm and mesopores with an average size of approximately 3.70–3.90 nm. Micropores with pore diameters less than 0.80 nm were found to play an especially major role in CO 2 adsorption by these materials. The MCF nanocomposites were determined to have large isosteric heats of adsorption from 23.32 to 36.48 kJ mol−1, and the MCF-2 specimen (the addition of 2 wt%) showed high CO 2 adsorption capacities of 4.58 and 3.19 mmol g−1 at 0 and 25 °C, respectively. This sample also demonstrated an excellent CO 2 /N 2 selectivity ratio of 23.71 at 25 °C and was readily recycled. The MCF-2 displayed a specific capacitance of 157.07 F g−1 at a current density of 1 A g−1 in a 6 M KOH electrolyte together with a superior rate retention of 71% at 15 A g−1 and so has potential applications in supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel AFIL organic solution was proposed for CO 2 capture. • The novel AFIL organic solution has obvious advantage in the recyclability and viscosity. • The regeneration energy was 2.30 GJ·t−1 CO 2 and 39.5% lower than that of MEA/water. • The reaction mechanism of [TEPAH][AICA]/NPA/EG solution was comprehensively elucidated. A novel sustainable amino functionalized ionic liquid (AFIL) organic solution of tetraethylene pentamine 5-amino-4-imidazolecarboxamide/n-propanol/ethylene glycol ([TEPAH][AICA]/NPA/EG) was proposed for CO 2 capture to reduce the regeneration energy consumption. The solution had an efficient absorption loading of 1.78 mol·mol−1, and it still maintained a good recyclability after 10 cycles (regeneration efficiency > 88%). Under this condition, the regeneration energy consumption was 2.30 GJ·t−1 CO 2 , which was 39.5% lower than that of MEA/water. The absorption and desorption mechanisms were investigated by 13C NMR. For CO 2 absorption reaction, N atom of [AICA]− combined with CO 2 to form the carbamate directly, while other amino groups followed the zwitterion formation and deprotonation. Then some carbamates combined with alcohol to form the alkyl carbonates. For CO 2 desorption reaction, both the alkyl carbonates and carbamates combined with AFILH+ to decompose, but the alkyl carbonates decomposed completely and a small amount of carbamates remained, indicating that carbonate was easier to decompose than carbamate. The novel [TEPAH][AICA]/NPA/EG solution with low energy consumption and good recyclability, which provides a sustainable strategy for advancing carbon capture technologies. [ABSTRACT FROM AUTHOR]

[Display omitted] • M-N-C (M = Fe, Co, Ni) with metal-pyridine N structure are synthesized for ECR. • ECR performance of M-N-C follow the selectivity order of Ni > Co > Fe. • ECR performance of M-N-C follow the activity order of Co > Ni > Fe. • Co-N-C with the highest activity can yield the syngas (CO/H 2 = 0.5∼2.11). • DFT results well supported the experimental results. It is of great importance to establish a definite relationship between structure and catalytic properties for developing highly efficient single-atom catalysts (SACs); however, this remains a challenge. Herein, three single atoms anchored on a nitrogen-doped carbon matrix (M-N-C, M = Fe, Co, Ni) with a metal-pyridine N structure were prepared and investigated as catalysts for electrochemical CO 2 reduction. M-N-C exhibit promising capability for CO 2 -to-CO conversion with the selectivity order of Ni > Co > Fe and the activity order of Co > Ni > Fe, in contrast to the previously reported performance order of Ni > Fe > Co. Among M-N-C catalysts, Ni-N-C shows superior selectivity (approximately 100% CO Faradaic efficiency from −0.66 V to −0.96 V), whereas Co-N-C exhibits high activity (CO current density = −24.24 mA cm−2 and CO turnover frequency = 7182 h−1 at −0.86 V) and capability of yielding syngas (CO/H 2 = 0.5∼2.11). Density functional theory calculations support the experimental selectivity and activity orders. This study presents a new possibility for improving the catalytic performance of SACs by investigating the coordinated environments of metal atoms. [ABSTRACT FROM AUTHOR]