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
The electrochemical carbon dioxide(CO_(2))reduction provides a means to upgrade CO_(2)into value-added chemicals.When powered by renewable electric-ity,CO_(2)electroreduction holds the promise of chemical manufacturin...The electrochemical carbon dioxide(CO_(2))reduction provides a means to upgrade CO_(2)into value-added chemicals.When powered by renewable electric-ity,CO_(2)electroreduction holds the promise of chemical manufacturing with carbon neutrality.A commercially relevant CO_(2)electroreduction process should be highly selective and productive toward desired products,energetically efficient for power conversion,and stable for long-term operation.To achieve these goals,designing gas-diffusion catalytic electrodes and prototyping reactors built upon in-depth understandings of the reaction mechanisms are of para-mount importance.In this review,the fundamentals of gas-diffusion electrodes are briefly presented.Then,the most recent advances in developing high-performance CO_(2)reduction using gas-diffusion electrodes are overviewed.Reactor engineering aiming at enhancing productivity,energy efficiency,CO_(2)single-pass utilization,and operating lifetime is further discussed.Challenges in developing CO_(2)electroreduction systems are included.The prospects for advancing CO_(2)electroreduction toward practical applications are also narrated.展开更多
Electrochemical reduction of CO_(2)to value-added chemicals using renewable electricity provides a promising strategy to achieve sustainable fuel production and carbon neutrality.Along with the development of electroc...Electrochemical reduction of CO_(2)to value-added chemicals using renewable electricity provides a promising strategy to achieve sustainable fuel production and carbon neutrality.Along with the development of electrocatalysts,fow cells with gas-diffusion electrodes(GDEs)have been used to reach commercially viable current densities for CO_(2)electrolysis,while the local environment and CO_(2)mass transport in the electrodes remain to be elucidated.In this review article,we highlight some insights into the microenvironment in the catalyst layer for CO_(2)electrolysis,including typical mass transport models for CO_(2)reduction in H-type cells and GDE fow cells,the effect of a hydrophobic microenvironment on CO_(2)mass transport and catalytic performance,and the formation of a gas/liquid balance and solid–liquid–gas interfaces for CO_(2)electrolysis.The insights and discussions in this article can provide important guidelines on the design of catalysts,electrodes,and electrolyzers for CO_(2)electrolysis,as well as other gas-involving electrocatalytic reactions.展开更多
A mathematic model is developed which is applied to analyze the main factors that affect electrode performance and to account for the process of reaction and mass transfer in gas-diffusion electrodes in contact with l...A mathematic model is developed which is applied to analyze the main factors that affect electrode performance and to account for the process of reaction and mass transfer in gas-diffusion electrodes in contact with liquid electrolytes. Electrochemical Thiele modulus φ^2 and electrochemical effectiveness factor η are introduced to elucidate the effects of diffusion on electrochemical reaction and utilization of the gas-diffusion electrode. Profile of the reactant along axial direction is discussed, dependence of electrode potential V on current density J, are predicated by means of the newly developed mathematical model.展开更多
This work investigated the degradation of tin – based gas-diffusion electrodes (GDE) and also a promising Bi2O3 GDE in electrochemical CO_(2) reduction in highly alkaline media which has not been studied before. The ...This work investigated the degradation of tin – based gas-diffusion electrodes (GDE) and also a promising Bi2O3 GDE in electrochemical CO_(2) reduction in highly alkaline media which has not been studied before. The contributions of the electrode wetting (or flooding, if excessively) and catalyst leaching on the degradation were analyzed. Therefore, electrochemical impedance spectroscopy was used to monitor the wetted surface area of the GDE in combination with post-mortem analysis of the penetration depth by visualizing the electrolyte’s cation in the GDE cross-section. Furthermore, to reveal a possible degradation of the electrocatalyst, its distribution was mapped in the GDEs cross-section after operation while the catholyte was additionally analyzed via ICP-MS. The results clearly demonstrate that the SnO_(2) catalyst dissolves in the reaction zone inside the GDE and might be partially redeposited near the GDEs surface. Since the redeposition process occurs only partially a steady loss of catalyst was observed impeding a clear distinction of the two degradation phenomena. Nevertheless, the deterioration of the electrode performance measured as faraday efficiency (FE) of the parasitic hydrogen evolution reaction (HER) qualitatively correlates with the differential double layer capacitance (Cdl). A significant difference of the rate of increase for the hydrogen FE and Cdl can be ascribed to the superposition of both above-mentioned degradation mechanisms. The demonstrated instability of SnO_(2) contrasts with the behavior of Bi2O3 GDE which is stabilized during CO_(2) conversion by redeposition of the diluted dissolved species as metallic Bi which is active for the CO_(2) reduction reaction.展开更多
In fuel cells,the structure of electrodes is an important factor which effect the cell performance.To improve the structure and the performance of electrodes,a new method of providing fuel cell electrodes is proposed ...In fuel cells,the structure of electrodes is an important factor which effect the cell performance.To improve the structure and the performance of electrodes,a new method of providing fuel cell electrodes is proposed in this paper.PTFE(polytetrafluoroethylene) and ethyne black was ground for about half an hour in a high_speed grinder,then the catalyst was added into the grinder and milled for an hour.This milled catalyst was transferred into a mixer followed by the addition of surface_active agent. After a suspension was formed,it was filtered under vacuum condition.Then a thin uniform filter_cake of the catalyst was formed,which was rolled together with a current_collecting mesh and a gas_ventilating film. Finally,the gas_difusion electrode of fuel cells was obtanied.The polarization property of the hydrogen electrode has been measured,where the Hg/HgO was used as reference electrode.And the effect of hydrophobic ethyne black and PTFE on electrodes in fuel cells was investigated.展开更多
In coal,the gas mainly exists in a free or an adsorption state.When the coal containing gas is damaged,gas desorption and diffusion will occur which can result in gas disaster.This research on gas desorption and diffu...In coal,the gas mainly exists in a free or an adsorption state.When the coal containing gas is damaged,gas desorption and diffusion will occur which can result in gas disaster.This research on gas desorption and diffusion provides a theoretical basis for gas disaster mechanism and prevention.The influence of pressure and temperature on gas diffusion is studied by the experiment.And the mechanism of pressure and temperature on gas diffusion is also analysed.The research results indicate that gas diffusion capacity increases with increasing temperature under the same pressure for the same coal sample.This is mainly because the temperature increases,gas molecular hot motion is severer,kinetic energy of gas molecular increases,and gas desorption quickens,therefore gas diffusion capacity changes stronger.Under other unchanged conditions,the greater gas adsorption balance pressure,the more gas adsorption content,and the higher the initial gas concentration.When gas diffusion begins,the greater the gas concentration gradient,the faster the gas diffusion speeds.展开更多
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Joint International Research Laboratory of Carbon-Based Functional Materials and Devices111 Project+1 种基金Collaborative Innovation Center of Suzhou Nano Science and TechnologyMinistry of Science and Technology,Grant/Award Number:2017YFA0204800。
文摘The electrochemical carbon dioxide(CO_(2))reduction provides a means to upgrade CO_(2)into value-added chemicals.When powered by renewable electric-ity,CO_(2)electroreduction holds the promise of chemical manufacturing with carbon neutrality.A commercially relevant CO_(2)electroreduction process should be highly selective and productive toward desired products,energetically efficient for power conversion,and stable for long-term operation.To achieve these goals,designing gas-diffusion catalytic electrodes and prototyping reactors built upon in-depth understandings of the reaction mechanisms are of para-mount importance.In this review,the fundamentals of gas-diffusion electrodes are briefly presented.Then,the most recent advances in developing high-performance CO_(2)reduction using gas-diffusion electrodes are overviewed.Reactor engineering aiming at enhancing productivity,energy efficiency,CO_(2)single-pass utilization,and operating lifetime is further discussed.Challenges in developing CO_(2)electroreduction systems are included.The prospects for advancing CO_(2)electroreduction toward practical applications are also narrated.
基金the support of a Sloan Research Fellowship from the Alfred P.Sloan Foundation(FG-2019-11694)。
文摘Electrochemical reduction of CO_(2)to value-added chemicals using renewable electricity provides a promising strategy to achieve sustainable fuel production and carbon neutrality.Along with the development of electrocatalysts,fow cells with gas-diffusion electrodes(GDEs)have been used to reach commercially viable current densities for CO_(2)electrolysis,while the local environment and CO_(2)mass transport in the electrodes remain to be elucidated.In this review article,we highlight some insights into the microenvironment in the catalyst layer for CO_(2)electrolysis,including typical mass transport models for CO_(2)reduction in H-type cells and GDE fow cells,the effect of a hydrophobic microenvironment on CO_(2)mass transport and catalytic performance,and the formation of a gas/liquid balance and solid–liquid–gas interfaces for CO_(2)electrolysis.The insights and discussions in this article can provide important guidelines on the design of catalysts,electrodes,and electrolyzers for CO_(2)electrolysis,as well as other gas-involving electrocatalytic reactions.
基金This researchis supported by Shanghai Education Committee(06-OZ-003)Shanghai Key Subject(p1501)
文摘A mathematic model is developed which is applied to analyze the main factors that affect electrode performance and to account for the process of reaction and mass transfer in gas-diffusion electrodes in contact with liquid electrolytes. Electrochemical Thiele modulus φ^2 and electrochemical effectiveness factor η are introduced to elucidate the effects of diffusion on electrochemical reaction and utilization of the gas-diffusion electrode. Profile of the reactant along axial direction is discussed, dependence of electrode potential V on current density J, are predicated by means of the newly developed mathematical model.
基金Parts of this work were funded by the German Federation of Industrial Research Associations(EWN03176/18).
文摘This work investigated the degradation of tin – based gas-diffusion electrodes (GDE) and also a promising Bi2O3 GDE in electrochemical CO_(2) reduction in highly alkaline media which has not been studied before. The contributions of the electrode wetting (or flooding, if excessively) and catalyst leaching on the degradation were analyzed. Therefore, electrochemical impedance spectroscopy was used to monitor the wetted surface area of the GDE in combination with post-mortem analysis of the penetration depth by visualizing the electrolyte’s cation in the GDE cross-section. Furthermore, to reveal a possible degradation of the electrocatalyst, its distribution was mapped in the GDEs cross-section after operation while the catholyte was additionally analyzed via ICP-MS. The results clearly demonstrate that the SnO_(2) catalyst dissolves in the reaction zone inside the GDE and might be partially redeposited near the GDEs surface. Since the redeposition process occurs only partially a steady loss of catalyst was observed impeding a clear distinction of the two degradation phenomena. Nevertheless, the deterioration of the electrode performance measured as faraday efficiency (FE) of the parasitic hydrogen evolution reaction (HER) qualitatively correlates with the differential double layer capacitance (Cdl). A significant difference of the rate of increase for the hydrogen FE and Cdl can be ascribed to the superposition of both above-mentioned degradation mechanisms. The demonstrated instability of SnO_(2) contrasts with the behavior of Bi2O3 GDE which is stabilized during CO_(2) conversion by redeposition of the diluted dissolved species as metallic Bi which is active for the CO_(2) reduction reaction.
文摘In fuel cells,the structure of electrodes is an important factor which effect the cell performance.To improve the structure and the performance of electrodes,a new method of providing fuel cell electrodes is proposed in this paper.PTFE(polytetrafluoroethylene) and ethyne black was ground for about half an hour in a high_speed grinder,then the catalyst was added into the grinder and milled for an hour.This milled catalyst was transferred into a mixer followed by the addition of surface_active agent. After a suspension was formed,it was filtered under vacuum condition.Then a thin uniform filter_cake of the catalyst was formed,which was rolled together with a current_collecting mesh and a gas_ventilating film. Finally,the gas_difusion electrode of fuel cells was obtanied.The polarization property of the hydrogen electrode has been measured,where the Hg/HgO was used as reference electrode.And the effect of hydrophobic ethyne black and PTFE on electrodes in fuel cells was investigated.
基金foundation by the State KeyBasic Research Program of China(No.2011CB201202)the Basic Science Research Special Foundation of China University of Mining&Technology(Beijing)(No.2009KZ03)the Basic Science Research Special Foundation of China University of Mining&Technology(Beijing)(No.2009QZ09)
文摘In coal,the gas mainly exists in a free or an adsorption state.When the coal containing gas is damaged,gas desorption and diffusion will occur which can result in gas disaster.This research on gas desorption and diffusion provides a theoretical basis for gas disaster mechanism and prevention.The influence of pressure and temperature on gas diffusion is studied by the experiment.And the mechanism of pressure and temperature on gas diffusion is also analysed.The research results indicate that gas diffusion capacity increases with increasing temperature under the same pressure for the same coal sample.This is mainly because the temperature increases,gas molecular hot motion is severer,kinetic energy of gas molecular increases,and gas desorption quickens,therefore gas diffusion capacity changes stronger.Under other unchanged conditions,the greater gas adsorption balance pressure,the more gas adsorption content,and the higher the initial gas concentration.When gas diffusion begins,the greater the gas concentration gradient,the faster the gas diffusion speeds.
