Reaction temperature is an important parameter to tune the selectivity and activity of electroche... more Reaction temperature is an important parameter to tune the selectivity and activity of electrochemical CO2 reduction reaction (CO2RR) due to different thermodynamics of CO2RR and competitive hydrogen evolution reaction (HER). In this work, temperature‐dependent CO2RR over Fe‐N‐C and Ni‐N‐C single‐atom catalysts are investigated from 303 to 343 K. Increasing the reaction temperature improves and decreases CO Faradaic efficiency over Fe‐N‐C and Ni‐N‐C catalysts at high overpotentials, respectively. CO current density over Fe‐N‐C catalyst increases with temperature, then gets into a plateau at 323 K, finally reaches the maximum value of 185.8 mA cm−2 at 343 K. While CO current density over Ni‐N‐C catalyst achieves the maximum value of 252.5 mA cm−2 at 323 K, and then drops significantly to 202.9 mA cm−2 at 343 K. Temperature programmed desorption results and density functional theory calculations reveal that the difference of temperature‐dependent variation on CO Faradaic efficiency and current density between Fe‐N‐C and Ni‐N‐C catalysts results from the varied adsorption strength of key reaction intermediates during CO2RR.
CO2 electrolysis is a promising route for achieving net‐zero emission through decarbonization. To... more CO2 electrolysis is a promising route for achieving net‐zero emission through decarbonization. To realize CO2 electrolysis toward practical application, beyond catalyst structures, it is also critical to rationally manipulate catalyst microenvironments such as the water at the electrode/electrolyte interface. Here, the role of interfacial water in CO2 electrolysis over Ni‐N‐C catalyst modified with different polymers is investigated. Benefiting from a hydrophilic electrode/electrolyte interface, the Ni‐N‐C catalyst modified with quaternary ammonia poly(N‐methyl‐piperidine‐co‐p‐terphenyl) shows a Faradaic efficiency of 95% and a partial current density of 665 mA cm−2 for CO production in an alkaline membrane electrode assembly electrolyzer. A scale‐up demonstration using a 100 cm2 electrolyzer achieves a CO production rate of 514 mL min−1 at a current of 80 A. In‐situ microscopy and spectroscopy measurements indicate that the hydrophilic interface significantly promotes the formation of the *COOH intermediate, rationalizing the high CO2 electrolysis performance.
The electrochemical CO2 reduction reaction (CO2RR) has been regarded as a promising technique for... more The electrochemical CO2 reduction reaction (CO2RR) has been regarded as a promising technique for converting CO2 into high‐value fuels and chemicals. Powered by renewable electricity, the CO2RR provides a viable strategy to mitigate the CO2 concentration in the atmosphere and close the anthropogenic carbon cycle. Recent studies exhibit that copper‐based catalysts are capable of reducing CO2 to C2+ products, such as ethylene and ethanol, which are of higher value compared with C1 products. The reaction process toward C2+ products involves the formation of key intermediate *CO, the C–C bonding, and the post‐C–C bonding to final products. This perspective is focusing on the mechanism leading to C2+ products, examining the evidence from in situ/operando spectroscopy and density functional theory calculations. The effects of Cu facet and electrolyte on catalytic performance are reviewed. An in depth discussion of mechanistic aspects of Cu catalyst is presented, shedding light on the intrinsic features of catalyst and electrode‐electrolyte interface, therefore moving towards an understanding of CO2RR at the atomic level.
The electrochemical CO2 reduction reaction (CO2RR) powered by renewable electricity is a promisin... more The electrochemical CO2 reduction reaction (CO2RR) powered by renewable electricity is a promising route to close the carbon cycle, but it suffers from low product selectivity and high overpotential. Here we develop nitrogen and boron co‐doped hollow carbon spheres (NB−CS) through the pyrolysis of a mixture comprising low‐molecular‐weight phenolic resols, melamine and boric acid. The optimized NB−CS catalyst presents high CO2RR performance and achieves a CO Faradaic efficiency of 95.1% at a low overpotential of 310 mV, superior to carbon spheres doped with nitrogen or boron alone. Structural and electrochemical characterizations indicate that the efficient CO2RR to CO over the NB−CS catalyst is likely ascribed to the unique graphitized architecture along with high conductivity, large surface area and high density of exposed N and B reactive sites. This work highlights opportunities to use cost‐effective and readily available carbon nanomaterials as efficient CO2RR catalysts.
By tailoring the microenvironments of a Ni–N–C catalyst in an acidic MEA electrolyzer, we achieve... more By tailoring the microenvironments of a Ni–N–C catalyst in an acidic MEA electrolyzer, we achieve a CO faradaic efficiency of 95% at 500 mA cm−2, and the CO2 loss is reduced by 86% at 300 mA cm−2 at pH 0.5, compared to alkaline CO2 electrolysis.
The design of efficient copper(Cu)‐based catalysts is critical for CO2electroreduction into multi... more The design of efficient copper(Cu)‐based catalysts is critical for CO2electroreduction into multiple carbon products. However, most Cu‐based catalysts are favorable for ethylene production while selective production of ethanol with high Faradaic efficiency and current density still remains a great challenge. Herein, we design a carbon‐coated CuOx(CuOx@C) catalyst through one‐pot pyrolysis of Cu‐based metal‐organic framework (MOF), which exhibits high selectivity for CO2electroreduction to ethanol with Faradaic efficiency of 46 %. Impressively, the partial current density of ethanol reaches 166 mA cm−2, which is higher than that of most reported catalysts. Operando Raman spectra indicate that the carbon coating can efficiently stabilize Cu+species under CO2electroreduction conditions, which promotes the C−C coupling step. Density functional theory (DFT) calculations reveal that the carbon layer can tune the key intermediate *HOCCH goes the hydrogenation pathway toward ethanol product...
The electrochemical CO2 reduction reaction (CO2RR) over Cu‐based catalysts shows great potential ... more The electrochemical CO2 reduction reaction (CO2RR) over Cu‐based catalysts shows great potential for converting CO2 into multicarbon (C2+) fuels and chemicals. Herein, we introduce an A2M2O7 structure into a Cu‐based catalyst through a solid‐state reaction synthesis method. The Cu2P2O7 catalyst is electrochemically reduced to metallic Cu with a significant structure evolution from grain aggregates to highly porous structure under CO2RR conditions. The reconstructed Cu2P2O7 catalyst achieves a Faradaic efficiency of 73.6 % for C2+ products at an applied current density of 350 mA cm−2, remarkably higher than the CuO counterparts. The reconstructed Cu2P2O7 catalyst has a high electrochemically active surface area, abundant defects, and low‐coordinated sites. In situ Raman spectroscopy and density functional theory calculations reveal that CO adsorption with bridge and atop configurations is largely improved on Cu with defects and low‐coordinated sites, which decreased the energy barrie...
Reaction temperature is an important parameter to tune the selectivity and activity of electroche... more Reaction temperature is an important parameter to tune the selectivity and activity of electrochemical CO2 reduction reaction (CO2RR) due to different thermodynamics of CO2RR and competitive hydrogen evolution reaction (HER). In this work, temperature‐dependent CO2RR over Fe‐N‐C and Ni‐N‐C single‐atom catalysts are investigated from 303 to 343 K. Increasing the reaction temperature improves and decreases CO Faradaic efficiency over Fe‐N‐C and Ni‐N‐C catalysts at high overpotentials, respectively. CO current density over Fe‐N‐C catalyst increases with temperature, then gets into a plateau at 323 K, finally reaches the maximum value of 185.8 mA cm−2 at 343 K. While CO current density over Ni‐N‐C catalyst achieves the maximum value of 252.5 mA cm−2 at 323 K, and then drops significantly to 202.9 mA cm−2 at 343 K. Temperature programmed desorption results and density functional theory calculations reveal that the difference of temperature‐dependent variation on CO Faradaic efficiency an...
Developing copper‐free catalysts for CO2 conversion into hydrocarbons and oxygenates is highly de... more Developing copper‐free catalysts for CO2 conversion into hydrocarbons and oxygenates is highly desirable for electrochemical CO2 reduction reaction (CO2RR). Herein, we report a cobalt phthalocyanine (CoPc) and zinc–nitrogen–carbon (Zn‐N‐C) tandem catalyst for CO2RR to CH4. This tandem catalyst shows a more than 100 times enhancement of the CH4/CO production rate ratio compared with CoPc or Zn‐N‐C alone. Density functional theory (DFT) calculations and electrochemical CO reduction reaction results suggest that CO2 is first reduced into CO over CoPc and then CO diffuses onto Zn‐N‐C for further conversion into CH4 over Zn‐N4 site, decoupling complicated CO2RR pathway on single active site into a two‐step tandem reaction. Moreover, mechanistic analysis indicates that CoPc not only generates CO but also enhances the availability of *H over adjacent N sites in Zn‐N4, which is the key to achieve the high CH4 production rate and understand the intriguing electrocatalytic behavior which is d...
Reaction temperature is an important parameter to tune the selectivity and activity of electroche... more Reaction temperature is an important parameter to tune the selectivity and activity of electrochemical CO2 reduction reaction (CO2RR) due to different thermodynamics of CO2RR and competitive hydrogen evolution reaction (HER). In this work, temperature‐dependent CO2RR over Fe‐N‐C and Ni‐N‐C single‐atom catalysts are investigated from 303 to 343 K. Increasing the reaction temperature improves and decreases CO Faradaic efficiency over Fe‐N‐C and Ni‐N‐C catalysts at high overpotentials, respectively. CO current density over Fe‐N‐C catalyst increases with temperature, then gets into a plateau at 323 K, finally reaches the maximum value of 185.8 mA cm−2 at 343 K. While CO current density over Ni‐N‐C catalyst achieves the maximum value of 252.5 mA cm−2 at 323 K, and then drops significantly to 202.9 mA cm−2 at 343 K. Temperature programmed desorption results and density functional theory calculations reveal that the difference of temperature‐dependent variation on CO Faradaic efficiency and current density between Fe‐N‐C and Ni‐N‐C catalysts results from the varied adsorption strength of key reaction intermediates during CO2RR.
CO2 electrolysis is a promising route for achieving net‐zero emission through decarbonization. To... more CO2 electrolysis is a promising route for achieving net‐zero emission through decarbonization. To realize CO2 electrolysis toward practical application, beyond catalyst structures, it is also critical to rationally manipulate catalyst microenvironments such as the water at the electrode/electrolyte interface. Here, the role of interfacial water in CO2 electrolysis over Ni‐N‐C catalyst modified with different polymers is investigated. Benefiting from a hydrophilic electrode/electrolyte interface, the Ni‐N‐C catalyst modified with quaternary ammonia poly(N‐methyl‐piperidine‐co‐p‐terphenyl) shows a Faradaic efficiency of 95% and a partial current density of 665 mA cm−2 for CO production in an alkaline membrane electrode assembly electrolyzer. A scale‐up demonstration using a 100 cm2 electrolyzer achieves a CO production rate of 514 mL min−1 at a current of 80 A. In‐situ microscopy and spectroscopy measurements indicate that the hydrophilic interface significantly promotes the formation of the *COOH intermediate, rationalizing the high CO2 electrolysis performance.
The electrochemical CO2 reduction reaction (CO2RR) has been regarded as a promising technique for... more The electrochemical CO2 reduction reaction (CO2RR) has been regarded as a promising technique for converting CO2 into high‐value fuels and chemicals. Powered by renewable electricity, the CO2RR provides a viable strategy to mitigate the CO2 concentration in the atmosphere and close the anthropogenic carbon cycle. Recent studies exhibit that copper‐based catalysts are capable of reducing CO2 to C2+ products, such as ethylene and ethanol, which are of higher value compared with C1 products. The reaction process toward C2+ products involves the formation of key intermediate *CO, the C–C bonding, and the post‐C–C bonding to final products. This perspective is focusing on the mechanism leading to C2+ products, examining the evidence from in situ/operando spectroscopy and density functional theory calculations. The effects of Cu facet and electrolyte on catalytic performance are reviewed. An in depth discussion of mechanistic aspects of Cu catalyst is presented, shedding light on the intrinsic features of catalyst and electrode‐electrolyte interface, therefore moving towards an understanding of CO2RR at the atomic level.
The electrochemical CO2 reduction reaction (CO2RR) powered by renewable electricity is a promisin... more The electrochemical CO2 reduction reaction (CO2RR) powered by renewable electricity is a promising route to close the carbon cycle, but it suffers from low product selectivity and high overpotential. Here we develop nitrogen and boron co‐doped hollow carbon spheres (NB−CS) through the pyrolysis of a mixture comprising low‐molecular‐weight phenolic resols, melamine and boric acid. The optimized NB−CS catalyst presents high CO2RR performance and achieves a CO Faradaic efficiency of 95.1% at a low overpotential of 310 mV, superior to carbon spheres doped with nitrogen or boron alone. Structural and electrochemical characterizations indicate that the efficient CO2RR to CO over the NB−CS catalyst is likely ascribed to the unique graphitized architecture along with high conductivity, large surface area and high density of exposed N and B reactive sites. This work highlights opportunities to use cost‐effective and readily available carbon nanomaterials as efficient CO2RR catalysts.
By tailoring the microenvironments of a Ni–N–C catalyst in an acidic MEA electrolyzer, we achieve... more By tailoring the microenvironments of a Ni–N–C catalyst in an acidic MEA electrolyzer, we achieve a CO faradaic efficiency of 95% at 500 mA cm−2, and the CO2 loss is reduced by 86% at 300 mA cm−2 at pH 0.5, compared to alkaline CO2 electrolysis.
The design of efficient copper(Cu)‐based catalysts is critical for CO2electroreduction into multi... more The design of efficient copper(Cu)‐based catalysts is critical for CO2electroreduction into multiple carbon products. However, most Cu‐based catalysts are favorable for ethylene production while selective production of ethanol with high Faradaic efficiency and current density still remains a great challenge. Herein, we design a carbon‐coated CuOx(CuOx@C) catalyst through one‐pot pyrolysis of Cu‐based metal‐organic framework (MOF), which exhibits high selectivity for CO2electroreduction to ethanol with Faradaic efficiency of 46 %. Impressively, the partial current density of ethanol reaches 166 mA cm−2, which is higher than that of most reported catalysts. Operando Raman spectra indicate that the carbon coating can efficiently stabilize Cu+species under CO2electroreduction conditions, which promotes the C−C coupling step. Density functional theory (DFT) calculations reveal that the carbon layer can tune the key intermediate *HOCCH goes the hydrogenation pathway toward ethanol product...
The electrochemical CO2 reduction reaction (CO2RR) over Cu‐based catalysts shows great potential ... more The electrochemical CO2 reduction reaction (CO2RR) over Cu‐based catalysts shows great potential for converting CO2 into multicarbon (C2+) fuels and chemicals. Herein, we introduce an A2M2O7 structure into a Cu‐based catalyst through a solid‐state reaction synthesis method. The Cu2P2O7 catalyst is electrochemically reduced to metallic Cu with a significant structure evolution from grain aggregates to highly porous structure under CO2RR conditions. The reconstructed Cu2P2O7 catalyst achieves a Faradaic efficiency of 73.6 % for C2+ products at an applied current density of 350 mA cm−2, remarkably higher than the CuO counterparts. The reconstructed Cu2P2O7 catalyst has a high electrochemically active surface area, abundant defects, and low‐coordinated sites. In situ Raman spectroscopy and density functional theory calculations reveal that CO adsorption with bridge and atop configurations is largely improved on Cu with defects and low‐coordinated sites, which decreased the energy barrie...
Reaction temperature is an important parameter to tune the selectivity and activity of electroche... more Reaction temperature is an important parameter to tune the selectivity and activity of electrochemical CO2 reduction reaction (CO2RR) due to different thermodynamics of CO2RR and competitive hydrogen evolution reaction (HER). In this work, temperature‐dependent CO2RR over Fe‐N‐C and Ni‐N‐C single‐atom catalysts are investigated from 303 to 343 K. Increasing the reaction temperature improves and decreases CO Faradaic efficiency over Fe‐N‐C and Ni‐N‐C catalysts at high overpotentials, respectively. CO current density over Fe‐N‐C catalyst increases with temperature, then gets into a plateau at 323 K, finally reaches the maximum value of 185.8 mA cm−2 at 343 K. While CO current density over Ni‐N‐C catalyst achieves the maximum value of 252.5 mA cm−2 at 323 K, and then drops significantly to 202.9 mA cm−2 at 343 K. Temperature programmed desorption results and density functional theory calculations reveal that the difference of temperature‐dependent variation on CO Faradaic efficiency an...
Developing copper‐free catalysts for CO2 conversion into hydrocarbons and oxygenates is highly de... more Developing copper‐free catalysts for CO2 conversion into hydrocarbons and oxygenates is highly desirable for electrochemical CO2 reduction reaction (CO2RR). Herein, we report a cobalt phthalocyanine (CoPc) and zinc–nitrogen–carbon (Zn‐N‐C) tandem catalyst for CO2RR to CH4. This tandem catalyst shows a more than 100 times enhancement of the CH4/CO production rate ratio compared with CoPc or Zn‐N‐C alone. Density functional theory (DFT) calculations and electrochemical CO reduction reaction results suggest that CO2 is first reduced into CO over CoPc and then CO diffuses onto Zn‐N‐C for further conversion into CH4 over Zn‐N4 site, decoupling complicated CO2RR pathway on single active site into a two‐step tandem reaction. Moreover, mechanistic analysis indicates that CoPc not only generates CO but also enhances the availability of *H over adjacent N sites in Zn‐N4, which is the key to achieve the high CH4 production rate and understand the intriguing electrocatalytic behavior which is d...
Uploads
Papers by Hefei Li