Molybdenum carbides are highly active for CO2 conversion to CO via the reverse water-gas shift(RWGS)reaction, however the large grain size up to micrometers renders its relatively lower active sites utilization effici...Molybdenum carbides are highly active for CO2 conversion to CO via the reverse water-gas shift(RWGS)reaction, however the large grain size up to micrometers renders its relatively lower active sites utilization efficiency while generating CH4 as a by-product. In this work, a homogeneously dispersed molybdenum carbide hybrid catalyst with sub-nanosized cluster(the average size as small as 0.5 nm) is prepared via a facile carbothermal treatment for highly selective CO2-CO reduction. The partially disordered Mo2C clusters are characterized by synchrotron high-resolution XRD and atomic resolution HAADF-STEM analysis, for which the source cause of the disorder is pinpointed by XAFS analysis to be the nitrogen intercalants from the carbonaceous precursor. The partially disordered Mo2C clusters show a RWGS rate as high as 184.4 μmol gMo2C-1s-1 at 400 ℃ with a superior selectivity toward CO(> 99.5%). This work 2 highlights a facile strategy for fabricating highly dispersed and partially disordered Mo2C clusters at a sub-nano size with beneficial N-doping for delivering high catalytic activity and operational stability.展开更多
Simulating photosynthesis to convert CO_(2)into valuable chemicals is an effective strategy to achieve sustainable carbon recycles,and the high conversion efficiency and selectivity of photocatalytic conversion CO_(2)...Simulating photosynthesis to convert CO_(2)into valuable chemicals is an effective strategy to achieve sustainable carbon recycles,and the high conversion efficiency and selectivity of photocatalytic conversion CO_(2)to specific chemicals are the key challenges.Herein,a direct Z-scheme Bi_(2)WO_(6)/La_(2)Ti_(2)O_(7)photocatalyst is successfully syn-thesized by electrostatic self-assembly method.The selectivity of CO_(2)reduction to CO is improved from 74%of La_(2)Ti_(2)O_(7)to nearly 100%,and the CO yield is 7.5 times that of individual La_(2)Ti_(2)O_(7).The improvement of the photocatalytic performance is attributed to the formation of Z-scheme heterojunction between Bi_(2)WO_(6)and La_(2)Ti_(2)O_(7),which facilitates the separation and transfer of photogenerated carriers.This work provides a new insight for the construction of efficient photocatalyst for selective reduction of CO_(2)to CO.展开更多
The discovery of efficient,selective,and stable electrocatalysts can be a key point to produce the largescale chemical fuels via electrochemical CO_(2) reduction(ECR).In this study,an earth-abundant and nontoxic ZnO-b...The discovery of efficient,selective,and stable electrocatalysts can be a key point to produce the largescale chemical fuels via electrochemical CO_(2) reduction(ECR).In this study,an earth-abundant and nontoxic ZnO-based electrocatalyst was developed for use in gas-diffusion electrodes(GDE),and the effect of nitrogen(N)doping on the ECR activity of ZnO electrocatalysts was investigated.Initially,a ZnO nanosheet was prepared via the hydrothermal method,and nitridation was performed at different times to control the N-doping content.With an increase in the N-doping content,the morphological properties of the nanosheet changed significantly,namely,the 2D nanosheets transformed into irregularly shaped nanoparticles.Furthermore,the ECR performance of Zn O electrocatalysts with different N-doping content was assessed in 1.0 M KHCO_(3) electrolyte using a gas-diffusion electrode-based ECR cell.While the ECR activity increased after a small amount of N doping,it decreased for higher N doping content.Among them,the N:ZnO-1 h electrocatalysts showed the best CO selectivity,with a faradaic efficiency(FE_(CO))of 92.7%at-0.73 V vs.reversible hydrogen electrode(RHE),which was greater than that of an undoped Zn O electrocatalyst(FE_(CO)of 63.4%at-0.78 V_(RHE)).Also,the N:ZnO-1 h electrocatalyst exhibited outstanding durability for 16 h,with a partial current density of-92.1 mA cm^(-2).This improvement of N:ZnO-1 h electrocatalyst can be explained by density functional theory calculations,demonstrating that this improvement of N:ZnO-1 h electrocatalyst comes from(ⅰ)the optimized active sites lowering the free energy barrier for the rate-determining step(RDS),and(ⅱ)the modification of electronic structure enhancing the electron transfer rate by N doping.展开更多
Reverse water gas shift(RWGS)reaction is a crucial process in CO_(2)utilization.Herein,Ni-and NiCe-containing hexagonal mesoporous silica(Ni-HMS and NiCe-HMS)catalysts were synthesized using an insitu one-pot method a...Reverse water gas shift(RWGS)reaction is a crucial process in CO_(2)utilization.Herein,Ni-and NiCe-containing hexagonal mesoporous silica(Ni-HMS and NiCe-HMS)catalysts were synthesized using an insitu one-pot method and applied for RWGS reaction.At certain reaction temperatures 500-750℃,Ni-HMS samples displayed a higher selectivity to the preferable CO than that of conventionally impregnated Ni/HMS catalyst.This could be originated from the smaller NiO nanoparticles over Ni-HMS catalyst.NiCe-HMS exhibited higher activity compared to Ni-HMS.The catalysts were characterized by means of TEM,XPS,XRD,H_(2)-TPR,CO_(2)-TPD,EPR and N_(2) adsorption-desortion technology.It was found that introduction of Ce created high concentration of oxygen vacancies,served as the active site for activating CO_(2).Also,this work analyzed the effect of the H_(2)/CO_(2)molar ratio on the best NiCe-HMS.When reaction gas H_(2)/CO_(2)molar ratio was 4 significantly decreased the selectivity to CO at low temperature,but triggered a higher CO_(2)conversion which is close to the equilibrium.展开更多
The reverse water-gas shift(RWGS)reaction holds great promise for CO_(2)reduction and achieving carbon neutrality,particularly when driven by renewable and abundant solar energy.Among various investigated catalysts,Co...The reverse water-gas shift(RWGS)reaction holds great promise for CO_(2)reduction and achieving carbon neutrality,particularly when driven by renewable and abundant solar energy.Among various investigated catalysts,Co-based materials have demonstrated high catalytic activity for CO_(2)hydrogenation,and the easily accessible Co or CoO_(x)catalysts tend to produce CH_(4)(via the Sabatier reaction)rather than CO(via the RWGS reaction)at relatively low temperatures(≤400℃).Besides the composition tuning to construct specific active sites(such as forming Co_(2)C),the manipulation of the chemical microenvironment is also considered a highly effective strategy for regulating product selectivity,as have been broadly demonstrated in electrochemistry and zeolite research fields.Herein,alkaline Sr sites aiming at enhancing the CO_(2)coverage at catalyst surface are placed in close proximity to the catalytically active Co centers,thus offering balanced supply of reactants within the reactive zone.The asdesigned SrCoO_(x)catalyst through in situ decomposition of the SrCoO_(2).52 precursor exhibits a significant enhancement in CO selectivity(from 42%to 91%)and exceptional stability throughout a 300-h continuous reaction.This work broadens the application scope of chemical microenvironment manipulation strategies and introduces a novel avenue for future photothermal catalyst development.展开更多
The reverse water–gas shift(RWGS)reaction combined with Fischer–Tropsch synthesis establishes a promising tandem catalytic system for transforming CO_(2)into valuable chemicals and fuels[1,2].However,the techno-econ...The reverse water–gas shift(RWGS)reaction combined with Fischer–Tropsch synthesis establishes a promising tandem catalytic system for transforming CO_(2)into valuable chemicals and fuels[1,2].However,the techno-economic assessment suggests that the RWGS reaction becomes viable and economically competitive only when catalysts with 100%CO selectivity(thus eliminating the downstream separation step),high activity,sufficiently long operational durability,and ideally produced from earth-abundant materials and energy-efficient routes,are available[3].展开更多
基金the National Natural Science Foundation of China(21872144,21972140 and 91645117)Liaoning Revitalization Talents Program(XLYC1907053)+2 种基金CAS Youth Innovation Promotion Association(2018220)Talents Innovation Project of Dalian City(2017RQ032 and 2016RD04)China Postdoctoral Science Foundation(2019TQ0314,2018M641726 and 2019M661146)。
文摘Molybdenum carbides are highly active for CO2 conversion to CO via the reverse water-gas shift(RWGS)reaction, however the large grain size up to micrometers renders its relatively lower active sites utilization efficiency while generating CH4 as a by-product. In this work, a homogeneously dispersed molybdenum carbide hybrid catalyst with sub-nanosized cluster(the average size as small as 0.5 nm) is prepared via a facile carbothermal treatment for highly selective CO2-CO reduction. The partially disordered Mo2C clusters are characterized by synchrotron high-resolution XRD and atomic resolution HAADF-STEM analysis, for which the source cause of the disorder is pinpointed by XAFS analysis to be the nitrogen intercalants from the carbonaceous precursor. The partially disordered Mo2C clusters show a RWGS rate as high as 184.4 μmol gMo2C-1s-1 at 400 ℃ with a superior selectivity toward CO(> 99.5%). This work 2 highlights a facile strategy for fabricating highly dispersed and partially disordered Mo2C clusters at a sub-nano size with beneficial N-doping for delivering high catalytic activity and operational stability.
基金supported by the National Natural Science Foundation of China(21972020 and 22172031)the Natural Science Foundation of Fujian Province(2021L3003)
文摘Simulating photosynthesis to convert CO_(2)into valuable chemicals is an effective strategy to achieve sustainable carbon recycles,and the high conversion efficiency and selectivity of photocatalytic conversion CO_(2)to specific chemicals are the key challenges.Herein,a direct Z-scheme Bi_(2)WO_(6)/La_(2)Ti_(2)O_(7)photocatalyst is successfully syn-thesized by electrostatic self-assembly method.The selectivity of CO_(2)reduction to CO is improved from 74%of La_(2)Ti_(2)O_(7)to nearly 100%,and the CO yield is 7.5 times that of individual La_(2)Ti_(2)O_(7).The improvement of the photocatalytic performance is attributed to the formation of Z-scheme heterojunction between Bi_(2)WO_(6)and La_(2)Ti_(2)O_(7),which facilitates the separation and transfer of photogenerated carriers.This work provides a new insight for the construction of efficient photocatalyst for selective reduction of CO_(2)to CO.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) (Grant Nos.2018R1A6A1A03024334,2019R1A2C1007637,2021M3I3A1082880,2021R1I1A1A01044174)the Basic Science Research Capacity Enhancement Project through Korea Basic Science Institute (Grant No.2019R1A6C1010024)。
文摘The discovery of efficient,selective,and stable electrocatalysts can be a key point to produce the largescale chemical fuels via electrochemical CO_(2) reduction(ECR).In this study,an earth-abundant and nontoxic ZnO-based electrocatalyst was developed for use in gas-diffusion electrodes(GDE),and the effect of nitrogen(N)doping on the ECR activity of ZnO electrocatalysts was investigated.Initially,a ZnO nanosheet was prepared via the hydrothermal method,and nitridation was performed at different times to control the N-doping content.With an increase in the N-doping content,the morphological properties of the nanosheet changed significantly,namely,the 2D nanosheets transformed into irregularly shaped nanoparticles.Furthermore,the ECR performance of Zn O electrocatalysts with different N-doping content was assessed in 1.0 M KHCO_(3) electrolyte using a gas-diffusion electrode-based ECR cell.While the ECR activity increased after a small amount of N doping,it decreased for higher N doping content.Among them,the N:ZnO-1 h electrocatalysts showed the best CO selectivity,with a faradaic efficiency(FE_(CO))of 92.7%at-0.73 V vs.reversible hydrogen electrode(RHE),which was greater than that of an undoped Zn O electrocatalyst(FE_(CO)of 63.4%at-0.78 V_(RHE)).Also,the N:ZnO-1 h electrocatalyst exhibited outstanding durability for 16 h,with a partial current density of-92.1 mA cm^(-2).This improvement of N:ZnO-1 h electrocatalyst can be explained by density functional theory calculations,demonstrating that this improvement of N:ZnO-1 h electrocatalyst comes from(ⅰ)the optimized active sites lowering the free energy barrier for the rate-determining step(RDS),and(ⅱ)the modification of electronic structure enhancing the electron transfer rate by N doping.
基金the Chengdu University of Technology Teachers Development Research Fund (No. 10912-2019KYQD07266)National Natural Science Foundation of China (No. 21806015) for financial support
文摘Reverse water gas shift(RWGS)reaction is a crucial process in CO_(2)utilization.Herein,Ni-and NiCe-containing hexagonal mesoporous silica(Ni-HMS and NiCe-HMS)catalysts were synthesized using an insitu one-pot method and applied for RWGS reaction.At certain reaction temperatures 500-750℃,Ni-HMS samples displayed a higher selectivity to the preferable CO than that of conventionally impregnated Ni/HMS catalyst.This could be originated from the smaller NiO nanoparticles over Ni-HMS catalyst.NiCe-HMS exhibited higher activity compared to Ni-HMS.The catalysts were characterized by means of TEM,XPS,XRD,H_(2)-TPR,CO_(2)-TPD,EPR and N_(2) adsorption-desortion technology.It was found that introduction of Ce created high concentration of oxygen vacancies,served as the active site for activating CO_(2).Also,this work analyzed the effect of the H_(2)/CO_(2)molar ratio on the best NiCe-HMS.When reaction gas H_(2)/CO_(2)molar ratio was 4 significantly decreased the selectivity to CO at low temperature,but triggered a higher CO_(2)conversion which is close to the equilibrium.
基金supported by the National Natural Science Foundation of China(22379065,22309080,22372078)the National Science Fund for Distinguished Young Scholars(22025202)+1 种基金the National Key Research and Development Program of China(2020YFA0710302)the Natural Science Foundation of Jiangsu Province of China(BK20232021)。
文摘The reverse water-gas shift(RWGS)reaction holds great promise for CO_(2)reduction and achieving carbon neutrality,particularly when driven by renewable and abundant solar energy.Among various investigated catalysts,Co-based materials have demonstrated high catalytic activity for CO_(2)hydrogenation,and the easily accessible Co or CoO_(x)catalysts tend to produce CH_(4)(via the Sabatier reaction)rather than CO(via the RWGS reaction)at relatively low temperatures(≤400℃).Besides the composition tuning to construct specific active sites(such as forming Co_(2)C),the manipulation of the chemical microenvironment is also considered a highly effective strategy for regulating product selectivity,as have been broadly demonstrated in electrochemistry and zeolite research fields.Herein,alkaline Sr sites aiming at enhancing the CO_(2)coverage at catalyst surface are placed in close proximity to the catalytically active Co centers,thus offering balanced supply of reactants within the reactive zone.The asdesigned SrCoO_(x)catalyst through in situ decomposition of the SrCoO_(2).52 precursor exhibits a significant enhancement in CO selectivity(from 42%to 91%)and exceptional stability throughout a 300-h continuous reaction.This work broadens the application scope of chemical microenvironment manipulation strategies and introduces a novel avenue for future photothermal catalyst development.
文摘The reverse water–gas shift(RWGS)reaction combined with Fischer–Tropsch synthesis establishes a promising tandem catalytic system for transforming CO_(2)into valuable chemicals and fuels[1,2].However,the techno-economic assessment suggests that the RWGS reaction becomes viable and economically competitive only when catalysts with 100%CO selectivity(thus eliminating the downstream separation step),high activity,sufficiently long operational durability,and ideally produced from earth-abundant materials and energy-efficient routes,are available[3].
