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 conversion of solar energy to produce clean hydrogen fuel through water splitting is an emerging strategy for efficiently storing solar energy in the form of solar fuel.This aligns with the increasing global deman...The conversion of solar energy to produce clean hydrogen fuel through water splitting is an emerging strategy for efficiently storing solar energy in the form of solar fuel.This aligns with the increasing global demand for the development of an ideal energy alternative to fossil fuels that does not emit greenhouse gases.Electrochemical(EC) and photoelectrochemical(PEC) water splitting technologies have garnered significant attention worldwide for advanced hydrogen solar fuel production in recent decades.To achieve sustainable green H_(2) production,it is essential to create efficient catalyst materials that are low-cost and can replace expensive noble metal-based catalysts.These characteristics make them an ideal catalyst material for the process.Two-dimensional MXenes with M_(n+1)X_(n) structure have been identified as a promising option for EC and PEC water splitting due to their superior hydrophilicity,metal-like conductivity,large surface area,and adjustable surface chemistry.Here,we present a summary of recent advancements in the synthesis and performance enhancement methods for MXene hybrid materials in hydrogen production through EC and PEC water splitting.Furthermore,we examine the challenges and insights associated with the rational design of MXene-based hybrid materials to facilitate efficient water splitting for sustainable solar fuel production.展开更多
A versatile use of a sulfur self-doped biochar derived from Camellia japonica(camellia)flowers is demonstrated as a multifunctional catalyst for overall water splitting and a supercapacitor.The native sulfur content i...A versatile use of a sulfur self-doped biochar derived from Camellia japonica(camellia)flowers is demonstrated as a multifunctional catalyst for overall water splitting and a supercapacitor.The native sulfur content in the camellia flower facilitates in situ self-doping of sulfur,which highly activates the camellia-driven biochar(SA-Came)as a multifunctional catalyst with the enhanced electron-transfer ability and long-term durability.For water splitting,an SA-Came-based electrode is highly stable and shows reaction activities in both hydrogen and oxygen evolution reactions,with overpotentials of 154 and 362 mV at 10 mA cm^(−2),respectively.For supercapacitors,SA-Came achieves a specific capacitance of 125.42 F g^(−1)at 2 A g^(−1)and high cyclic stability in a three-electrode system in a 1 M KOH electrolyte.It demonstrated a high energy density of 34.54 Wh kg^(−1)at a power density of 1600 W kg^(−1)as a symmetric hybrid supercapacitor device with a wide working potential range of 0-1.6 V.展开更多
2D materials are regarded as promising electrocatalysts for water splitting because of their advances in providing ample active sites and improving electrochemical reaction kinetics.2D MoSe_(2)has a greater intrinsic ...2D materials are regarded as promising electrocatalysts for water splitting because of their advances in providing ample active sites and improving electrochemical reaction kinetics.2D MoSe_(2)has a greater intrinsic electrical conductivity and lower Gibbs free energy for reactant adsorption.However,there is still room for improvement in the electrocatalytic performance of MoSe_(2)for high-performance electrochemical water splitting devices.Herein,the in situ preparation of heterostructure made of covalently bonded MoSe_(2)and rGO is reported.The obtained electrocatalyst contains the aggregated 3D structured MoSe_(2)over rGO,which is covalently bonded together with more edge sites.The active edge sites of MoSe_(2)/rGO are dynamically involved in the electrocatalytic activity while facilitating electron transfer.Hence,the MoSe_(2)/rGO heterostructure requires a low cell voltage of 1.64 V to reach 100 mA cm^(−2)in water splitting with high reaction kinetics.The aggregated MoSe_(2)over rGO with more edge sites exposed by the 3D structure of MoSe_(2)and the interfacial covalent bond in between them provides a favorable electronic structure for the HER and OER with low overpotentials and high current densities and enhances the stability of the electrocatalyst.This work presents an attractive and cost-effective electrocatalyst suitable for industrial-scale hydrogen fuel production.展开更多
Electrochemical nitrogen reduction reaction(NRR)is a sustainable alterna-tive to the Haber-Bosch process for ammonia(NH3)production.However,the significant uphill energy in the multistep NRR pathway is a bottleneck fo...Electrochemical nitrogen reduction reaction(NRR)is a sustainable alterna-tive to the Haber-Bosch process for ammonia(NH3)production.However,the significant uphill energy in the multistep NRR pathway is a bottleneck for favorable serial reactions.To overcome this challenge,we designed a vanadium oxide/nitride(V_(2)O_(3)/VN)hybrid electrocatalyst in which V_(2)O_(3)and VN coex-ist coherently at the heterogeneous interface.Since single-phase V_(2)O_(3)and VN exhibit different surface catalytic kinetics for NRR,the V_(2)O_(3)/VN hybrid elec-trocatalyst can provide alternating reaction pathways,selecting a lower energy pathway for each material in the serial NRR pathway.As a result,the ammo-nia yield of the V_(2)O_(3)/VN hybrid electrocatalyst was 219.6µg h^(-1)cm^(-2),and the Faradaic efficiency was 18.9%,which is much higher than that of single-phase VN,V_(2)O_(3),and VNxOy solid solution catalysts without heterointerfaces.Density functional theory calculations confirmed that the composition of these hybrid electrocatalysts allows NRR to proceed from a multistep reduction reaction to a low-energy reaction pathway through the migration and adsorption of interme-diate species.Therefore,the design of metal oxide/nitride hybrids with coherent heterointerfaces provides a novel strategy for synthesizing highly efficient elec-trochemical catalysts that induce steps favorable for the efficient low-energy progression of NRR.展开更多
Efficient and cost-effective electrocatalysts that can operate across a wide range of pH conditions are essential for green hydrogen production.Inspired by biological systems,Fe_(7)S_(8)nanoparticles incorporated on p...Efficient and cost-effective electrocatalysts that can operate across a wide range of pH conditions are essential for green hydrogen production.Inspired by biological systems,Fe_(7)S_(8)nanoparticles incorporated on polydopamine matrix electrocatalyst were synthesized by co-precipitation and annealing process.The resulting Fe_(7)S_(8)/C electrocatalyst possesses a three-dimensional structure and exhibits enhanced electrocatalytic performance for hydrogen production across various pH conditions.Notably,the Fe_(7)S_(8)/C electrocatalyst demonstrates exceptional activity,achieving low overpotentials of 90.6,45.9,and 107.4 mV in acidic,neutral,and alkaline environments,respectively.Electrochemical impedance spectroscopy reveals that Fe_(7)S_(8)/C exhibits the lowest charge transfer resistance under neutral conditions,indicating an improved proton-coupled electron transfer process.Continuous-wave electron paramagnetic resonance results confirm a change in the valence state of Fe from 3+to 1+during the hydrogen evolution reaction(HER).These findings closely resemble the behavior of natural[FeFe]-hydrogenase,known for its superior hydrogen production in neutral conditions.The remarkable performance of our Fe_(7)S_(8)/C electrocatalyst opens up new possibilities for utilizing bioinspired materials as catalysts for the HER.展开更多
Electrochemical nitrate reduction(ENR)is an economical and eco-friendly method for converting industrial wastewater into valuable ammonia under atmospheric conditions.The main challenge lies in designing and developin...Electrochemical nitrate reduction(ENR)is an economical and eco-friendly method for converting industrial wastewater into valuable ammonia under atmospheric conditions.The main challenge lies in designing and developing highly durable ENR electrocatalysts.This study introduces defect-rich mesoporous CuO_(x) nanowires electrocatalyst synthesized using a novel solution-flame(sol-flame)hybrid method to control mesoporosity and introduce surface defects,thereby enhancing the electrochemical nitrate-toammonia production performance.We found surface defects(oxygen vacancies and Cu^(+))and unique mesoporous nanowire structure composed of tightly interconnected nanoparticles.The sol-flamesynthesized CuO_(x) nanowires(sf-CuO NWs)achieved superior ammonia yield rate(0.51 mmol h^(-1)cm^(-2)),faradaic efficiency(97.3%),and selectivity(86.2%)in 1 M KOH electrolyte(2000 ppm nitrate).This performance surpasses that of non-porous and less-defective CuO NWs and is attributed to the increased surface area and rapid electron transport facilitated by the distinctive morphology and generated defects.Theoretical calculation further suggests oxygen vacancies enhance NO_(3)^(-)adsorption on the sf-CuO NWs’surface and mitigate the competing hydrogen evolution reaction.This study outlines a strategic design and simple synthesis approach for nanowire electrocatalysts that boost the efficiency of electrochemical nitrate-to-ammonia conversion.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the result of a research project conducted with the funds of the Open R&D program of Korea Electric Power Corporation (R23XO04)supported by the Technology Innovation Program funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea) (K_G012002238601)+2 种基金by “Regional Innovation Strategy (RIS)” through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (MOE) (2021RIS-002)by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2021M3I3A1082880)by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20224000000320)。
文摘The conversion of solar energy to produce clean hydrogen fuel through water splitting is an emerging strategy for efficiently storing solar energy in the form of solar fuel.This aligns with the increasing global demand for the development of an ideal energy alternative to fossil fuels that does not emit greenhouse gases.Electrochemical(EC) and photoelectrochemical(PEC) water splitting technologies have garnered significant attention worldwide for advanced hydrogen solar fuel production in recent decades.To achieve sustainable green H_(2) production,it is essential to create efficient catalyst materials that are low-cost and can replace expensive noble metal-based catalysts.These characteristics make them an ideal catalyst material for the process.Two-dimensional MXenes with M_(n+1)X_(n) structure have been identified as a promising option for EC and PEC water splitting due to their superior hydrophilicity,metal-like conductivity,large surface area,and adjustable surface chemistry.Here,we present a summary of recent advancements in the synthesis and performance enhancement methods for MXene hybrid materials in hydrogen production through EC and PEC water splitting.Furthermore,we examine the challenges and insights associated with the rational design of MXene-based hybrid materials to facilitate efficient water splitting for sustainable solar fuel production.
基金National Research Foundation of Korea,Grant/Award Numbers:2016M3D1A1021141,2020R1A2C2006077,2022R1A2C1012419,2021R1A4A1024129,2021R1A5A1030054Ministry of Trade,Industry and Energy(MOTIE,Korea),Grant/Award Number:20213030040590。
文摘A versatile use of a sulfur self-doped biochar derived from Camellia japonica(camellia)flowers is demonstrated as a multifunctional catalyst for overall water splitting and a supercapacitor.The native sulfur content in the camellia flower facilitates in situ self-doping of sulfur,which highly activates the camellia-driven biochar(SA-Came)as a multifunctional catalyst with the enhanced electron-transfer ability and long-term durability.For water splitting,an SA-Came-based electrode is highly stable and shows reaction activities in both hydrogen and oxygen evolution reactions,with overpotentials of 154 and 362 mV at 10 mA cm^(−2),respectively.For supercapacitors,SA-Came achieves a specific capacitance of 125.42 F g^(−1)at 2 A g^(−1)and high cyclic stability in a three-electrode system in a 1 M KOH electrolyte.It demonstrated a high energy density of 34.54 Wh kg^(−1)at a power density of 1600 W kg^(−1)as a symmetric hybrid supercapacitor device with a wide working potential range of 0-1.6 V.
基金National Research Foundation of Korea,Grant/Award Number:RS-2023-00248447Ministry of Science and the Korean Government(MSIT),Republic of Korea,Grant/Award Number:RS-2023-00248447+3 种基金The Korea Institute of Energy Technology Evaluation and Planning(KETEP),Grant/Award Numbers:RS-2023-00242227,20224000000320Ministry of Trade,Industry,and Energy,Republic of Korea,Grant/Award Numbers:RS-2023-00242227,20224000000320Korea Electric Power Corporation(KEPCO),Grant/Award Number:R23XO04KENTECH Research Grant,Grant/Award Number:KRG2022-01-016。
文摘2D materials are regarded as promising electrocatalysts for water splitting because of their advances in providing ample active sites and improving electrochemical reaction kinetics.2D MoSe_(2)has a greater intrinsic electrical conductivity and lower Gibbs free energy for reactant adsorption.However,there is still room for improvement in the electrocatalytic performance of MoSe_(2)for high-performance electrochemical water splitting devices.Herein,the in situ preparation of heterostructure made of covalently bonded MoSe_(2)and rGO is reported.The obtained electrocatalyst contains the aggregated 3D structured MoSe_(2)over rGO,which is covalently bonded together with more edge sites.The active edge sites of MoSe_(2)/rGO are dynamically involved in the electrocatalytic activity while facilitating electron transfer.Hence,the MoSe_(2)/rGO heterostructure requires a low cell voltage of 1.64 V to reach 100 mA cm^(−2)in water splitting with high reaction kinetics.The aggregated MoSe_(2)over rGO with more edge sites exposed by the 3D structure of MoSe_(2)and the interfacial covalent bond in between them provides a favorable electronic structure for the HER and OER with low overpotentials and high current densities and enhances the stability of the electrocatalyst.This work presents an attractive and cost-effective electrocatalyst suitable for industrial-scale hydrogen fuel production.
基金National Research Foundation of Korea,Grant/Award Numbers:2022R1A2C1012419,2022R1A2C1011559,2022R1C1C1007004。
文摘Electrochemical nitrogen reduction reaction(NRR)is a sustainable alterna-tive to the Haber-Bosch process for ammonia(NH3)production.However,the significant uphill energy in the multistep NRR pathway is a bottleneck for favorable serial reactions.To overcome this challenge,we designed a vanadium oxide/nitride(V_(2)O_(3)/VN)hybrid electrocatalyst in which V_(2)O_(3)and VN coex-ist coherently at the heterogeneous interface.Since single-phase V_(2)O_(3)and VN exhibit different surface catalytic kinetics for NRR,the V_(2)O_(3)/VN hybrid elec-trocatalyst can provide alternating reaction pathways,selecting a lower energy pathway for each material in the serial NRR pathway.As a result,the ammo-nia yield of the V_(2)O_(3)/VN hybrid electrocatalyst was 219.6µg h^(-1)cm^(-2),and the Faradaic efficiency was 18.9%,which is much higher than that of single-phase VN,V_(2)O_(3),and VNxOy solid solution catalysts without heterointerfaces.Density functional theory calculations confirmed that the composition of these hybrid electrocatalysts allows NRR to proceed from a multistep reduction reaction to a low-energy reaction pathway through the migration and adsorption of interme-diate species.Therefore,the design of metal oxide/nitride hybrids with coherent heterointerfaces provides a novel strategy for synthesizing highly efficient elec-trochemical catalysts that induce steps favorable for the efficient low-energy progression of NRR.
基金Outsourced R&D Project of Korea Electric Power Corporation(KEPCO),Grant/Award Number:R23XO04National Research Foundation of Korea(NRF)+7 种基金Korean government(MSIT),Grant/Award Numbers:NRF-2021M3H4A6A01045764,2020M3H4A3106313,2021R1C1C1004264,2021R1A4A1032114Korea Institute for Advancement of Technology(KIAT)Ministry of Trade,Industry,and Energy(MOTIE),Korea,Grant/Award Number:P0025273Korea Institute of Energy Technology Evaluation and Planning(KETEP)and the Ministry of Trade,Industry&Energy(MOTIE)of the Republic of Korea,Grant/Award Number:20224000000320KENTECH Research GrantKorea Institute of Energy Technology,Republic of Korea,Grant/Award Number:KRG2022-01-016Regional Innovation Strategy(RIS)through the National Research Foundation of Korea(NRF)Ministry of Education(MOE),Grant/Award Number:2021RIS-002。
文摘Efficient and cost-effective electrocatalysts that can operate across a wide range of pH conditions are essential for green hydrogen production.Inspired by biological systems,Fe_(7)S_(8)nanoparticles incorporated on polydopamine matrix electrocatalyst were synthesized by co-precipitation and annealing process.The resulting Fe_(7)S_(8)/C electrocatalyst possesses a three-dimensional structure and exhibits enhanced electrocatalytic performance for hydrogen production across various pH conditions.Notably,the Fe_(7)S_(8)/C electrocatalyst demonstrates exceptional activity,achieving low overpotentials of 90.6,45.9,and 107.4 mV in acidic,neutral,and alkaline environments,respectively.Electrochemical impedance spectroscopy reveals that Fe_(7)S_(8)/C exhibits the lowest charge transfer resistance under neutral conditions,indicating an improved proton-coupled electron transfer process.Continuous-wave electron paramagnetic resonance results confirm a change in the valence state of Fe from 3+to 1+during the hydrogen evolution reaction(HER).These findings closely resemble the behavior of natural[FeFe]-hydrogenase,known for its superior hydrogen production in neutral conditions.The remarkable performance of our Fe_(7)S_(8)/C electrocatalyst opens up new possibilities for utilizing bioinspired materials as catalysts for the HER.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.-RS-2024-00335976)。
文摘Electrochemical nitrate reduction(ENR)is an economical and eco-friendly method for converting industrial wastewater into valuable ammonia under atmospheric conditions.The main challenge lies in designing and developing highly durable ENR electrocatalysts.This study introduces defect-rich mesoporous CuO_(x) nanowires electrocatalyst synthesized using a novel solution-flame(sol-flame)hybrid method to control mesoporosity and introduce surface defects,thereby enhancing the electrochemical nitrate-toammonia production performance.We found surface defects(oxygen vacancies and Cu^(+))and unique mesoporous nanowire structure composed of tightly interconnected nanoparticles.The sol-flamesynthesized CuO_(x) nanowires(sf-CuO NWs)achieved superior ammonia yield rate(0.51 mmol h^(-1)cm^(-2)),faradaic efficiency(97.3%),and selectivity(86.2%)in 1 M KOH electrolyte(2000 ppm nitrate).This performance surpasses that of non-porous and less-defective CuO NWs and is attributed to the increased surface area and rapid electron transport facilitated by the distinctive morphology and generated defects.Theoretical calculation further suggests oxygen vacancies enhance NO_(3)^(-)adsorption on the sf-CuO NWs’surface and mitigate the competing hydrogen evolution reaction.This study outlines a strategic design and simple synthesis approach for nanowire electrocatalysts that boost the efficiency of electrochemical nitrate-to-ammonia conversion.