Developing an industrially relevant electrode with high catalytic activity,stability,and tunable composition/size for large-scale water electrolysis is a significant challenge.We have created an integrated elec-trode(...Developing an industrially relevant electrode with high catalytic activity,stability,and tunable composition/size for large-scale water electrolysis is a significant challenge.We have created an integrated elec-trode(NFM30-N)for the oxygen evolution reaction(OER)using a facile top-down approach that combines arc melting with dealloying-oxidation.Due to the dealloying-oxidation effect,the asderived porous amorphous M-O,M-OH,and M-OOH(M=Ni,Fe)nanocones cover the basic NiFeMn alloy.This integrated design enables NFM30-N to exhibit outstanding OER performance at high current densities,requiring low overpotentials of only 282 and 323 mV to achieve large current densities of 100 and 500 mA cm^(-2),respectively.It also displays a small Tafel slope of 44.1 mV dec^(-1) and remarkable stability for over 100 h at 100 and 500 mA cm^(-2).When used as an anode,a two-electrode electrolyzer cell with NFM30-N at 500 mA cm^(-2) only requires a cell voltage of 1.619 V and exhibits excellent stability,with almost no performance degradation after continuous chronopotentiometry test for each 100 h at 500 and 100 mA cm^(-2).This exceptional OER electrocatalytic performance is attributed to the integrated structure providing high electrical conductivity and stability,the presence of numerous active sites due to dealloying and the amorphous structure,and the promotion of the OER process by M-O,M-OH,and M-OOH species.This work offers a novel idea for fabricating integrated,industrially relevant electrocatalytic electrodes through traditional metallurgy combined with dealloying-oxidation.展开更多
Renewable energy-driven water electrolysis is considered as an environmentally friendly hydrogen(H2)production technology.Replacing the oxygen evolution reaction(OER)with the urea oxidation reaction(UOR)is a more effe...Renewable energy-driven water electrolysis is considered as an environmentally friendly hydrogen(H2)production technology.Replacing the oxygen evolution reaction(OER)with the urea oxidation reaction(UOR)is a more effective way to improve the energy efficiency of H2 generation.Herein,a highly effi-cient 2D NiFeMo-based UOR catalyst and 1D NiFeMo-based HER catalyst are prepared by adjusting the concentration of MoO_(4)^(-).The MoO_(4)^(-)can serve as the key regulator to adjust the balance between the electrolytic dissociation(α)of the reactants and the supersaturation(S)to modulate the morphological and electronic structure.The prepared 2D NiFeMo nanosheet UOR catalyst and 1D NiFeMo nanorod HER catalyst can achieve a current density of 100 mA cm^(−2)at a potential of 1.36 and 0.062 V,respectively.In a HER/UOR system,a cell voltage of 1.58 V is needed to achieve a current density of 100 mA cm^(−2).The HER/UOR system operated stably for over 60 h with 3 times the direct water electrolysis current den-sity.Moreover,the in situ Raman characterization coupled with XPS analysis clarifies that the addition of high-valence Mo can lower the transition energy barrier between the low and high oxidation state of Ni,which in turn lowers the overpotential of UOR.This work provides a novel strategy for synthesizing morphology-dependent electrocatalysts for different catalytic systems.展开更多
Anion-exchange membrane water electrolyzers(AEMWEs)for green hydrogen production have received intensive attention due to their feasibility of using earth-abundant NiFe-based catalysts.By introducing a third metal int...Anion-exchange membrane water electrolyzers(AEMWEs)for green hydrogen production have received intensive attention due to their feasibility of using earth-abundant NiFe-based catalysts.By introducing a third metal into NiFe-based catalysts to construct asymmetrical M-NiFe units,the d-orbital and electronic structures can be adjusted,which is an important strategy to achieve sufficient oxygen evolution reaction(OER)performance in AEMWEs.Herein,the ternary NiFeM(M:La,Mo)catalysts featured with distinct M-NiFe units and varying d-orbitals are reported in this work.Experimental and theoretical calculation results reveal that the doping of La leads to optimized hybridization between d orbital in NiFeM and 2p in oxygen,resulting in enhanced adsorption strength of oxygen intermediates,and reduced rate-determining step energy barrier,which is responsible for the enhanced OER performance.More critically,the obtained NiFeLa catalyst only requires 1.58 V to reach 1 A cm^(−2) in an anion exchange membrane electrolyzer and demonstrates excellent long-term stability of up to 600 h.展开更多
The oxygen evolution reaction(OER)has received widespread attention as an anodic reaction in various key electrochemical processes such as water splitting,carbon dioxide electroreduction,and ammonia electrosynthesis.T...The oxygen evolution reaction(OER)has received widespread attention as an anodic reaction in various key electrochemical processes such as water splitting,carbon dioxide electroreduction,and ammonia electrosynthesis.Therefore,there is an urgent need for efficient non-precious OER electrocatalysts to reduce the energy consumption and cost of these processes.NiFe layered double hydroxides(LDHs)with tunable electronic structure properties exhibit excellent OER intrinsic activity.However,their low electrical conductivity and tendency to agglomerate during electrocatalysis hinder their performance in OER.Herein,benefiting from the attraction of abundant negatively charged groups on the MXene surface towards Ni^(2+)and Fe^(3+),a heterostructure of highly conductive Mo_(2)CT_(x)MXene and NiFe alloy/LDH composite was prepared using a simple in-situ growth strategy.Combining experimental results and theoretical calculations,it is revealed that Mo_(2)CT_(x)MXene,as a substrate,significantly improves the OER performance of the NiFe-based catalyst by enhancing the electrical conductivity,mitigating the agglomeration,accelerating the oxidation and tuning the electronic structure.Consequently,in 1 M KOH electrolyte,the overpotential required to reach an OER current density of 10 mA cm^(-2)is only 230 mV,and the catalyst maintains high stability even after 3000 cyclic voltammetry cycles.This work expands the application of Mo_(2)CT_(x)MXene in electrocatalysis,and provides useful experience for the regulation of LDH-based electrocatalysts.展开更多
Reducing the cost and improving the electrocatalytic activity are the key to developing high efficiency electrocatalysts for oxygen evolution reaction(OER).Here,bimetallic NiFe-based metal-organic framework(MOF)was pr...Reducing the cost and improving the electrocatalytic activity are the key to developing high efficiency electrocatalysts for oxygen evolution reaction(OER).Here,bimetallic NiFe-based metal-organic framework(MOF)was prepared by solvothermal method,and then used as precursor to prepare NiFe-based MOF-derived materials by pyrolysis.The effects of different metal ratios and pyrolysis temperatures on the sample structure and OER electrocatalytic performance were investigated and compared.The experimental results showed that when the metal molar ratio was Fe:Ni=1:5 and the pyrolysis temperature was 450℃,the sample(FeNi_(5)-MOF-450)exhibits a composite structure of Ni Fe_(2)O_(4)/FeNi_(3)/C and owns the superior electrocatalytic activity in OER.When the current density is 100 mA·cm^(-2),the overpotential of the sample was 377 mV with Tafel slope of 56.2 mV·dec^(-1),which indicates that FeNi_(5)-MOF-450 exhibits superior electrocatalytic performance than the commercial RuO_(2).Moreover,the long-term stability of FeNi_(5)-MOF-450 further promotes its development in OER.This work demonstrated that the regulatory methods such as component optimization can effectively improve the OER catalytic performance of NiFe-based MOF-derived materials.展开更多
基金the National Natural Science Foundation of China(Nos.52174365,52004155,52334009 and 52130204)the National Key R&D Program of China(Nos.2023YFB3506701 and 2022YFB3706801)the Science and Technology Commission of Shanghai Municipality(No.21DZ1208900).
文摘Developing an industrially relevant electrode with high catalytic activity,stability,and tunable composition/size for large-scale water electrolysis is a significant challenge.We have created an integrated elec-trode(NFM30-N)for the oxygen evolution reaction(OER)using a facile top-down approach that combines arc melting with dealloying-oxidation.Due to the dealloying-oxidation effect,the asderived porous amorphous M-O,M-OH,and M-OOH(M=Ni,Fe)nanocones cover the basic NiFeMn alloy.This integrated design enables NFM30-N to exhibit outstanding OER performance at high current densities,requiring low overpotentials of only 282 and 323 mV to achieve large current densities of 100 and 500 mA cm^(-2),respectively.It also displays a small Tafel slope of 44.1 mV dec^(-1) and remarkable stability for over 100 h at 100 and 500 mA cm^(-2).When used as an anode,a two-electrode electrolyzer cell with NFM30-N at 500 mA cm^(-2) only requires a cell voltage of 1.619 V and exhibits excellent stability,with almost no performance degradation after continuous chronopotentiometry test for each 100 h at 500 and 100 mA cm^(-2).This exceptional OER electrocatalytic performance is attributed to the integrated structure providing high electrical conductivity and stability,the presence of numerous active sites due to dealloying and the amorphous structure,and the promotion of the OER process by M-O,M-OH,and M-OOH species.This work offers a novel idea for fabricating integrated,industrially relevant electrocatalytic electrodes through traditional metallurgy combined with dealloying-oxidation.
基金supported by the National Natural Science Foundation of China(No.22308322)the Science Foundation of Donghai Laboratory(No.DH-2022ZY0010)the R&D Project of State Grid Corporation of China(No.5108-202218280A-2-439-XG).
文摘Renewable energy-driven water electrolysis is considered as an environmentally friendly hydrogen(H2)production technology.Replacing the oxygen evolution reaction(OER)with the urea oxidation reaction(UOR)is a more effective way to improve the energy efficiency of H2 generation.Herein,a highly effi-cient 2D NiFeMo-based UOR catalyst and 1D NiFeMo-based HER catalyst are prepared by adjusting the concentration of MoO_(4)^(-).The MoO_(4)^(-)can serve as the key regulator to adjust the balance between the electrolytic dissociation(α)of the reactants and the supersaturation(S)to modulate the morphological and electronic structure.The prepared 2D NiFeMo nanosheet UOR catalyst and 1D NiFeMo nanorod HER catalyst can achieve a current density of 100 mA cm^(−2)at a potential of 1.36 and 0.062 V,respectively.In a HER/UOR system,a cell voltage of 1.58 V is needed to achieve a current density of 100 mA cm^(−2).The HER/UOR system operated stably for over 60 h with 3 times the direct water electrolysis current den-sity.Moreover,the in situ Raman characterization coupled with XPS analysis clarifies that the addition of high-valence Mo can lower the transition energy barrier between the low and high oxidation state of Ni,which in turn lowers the overpotential of UOR.This work provides a novel strategy for synthesizing morphology-dependent electrocatalysts for different catalytic systems.
基金financially supported by the National Natural Science Foundation of China(22309137,22279095)Open subject project State Key Laboratory of New Textile Materials and Advanced Processing Technologies(FZ2023001).
文摘Anion-exchange membrane water electrolyzers(AEMWEs)for green hydrogen production have received intensive attention due to their feasibility of using earth-abundant NiFe-based catalysts.By introducing a third metal into NiFe-based catalysts to construct asymmetrical M-NiFe units,the d-orbital and electronic structures can be adjusted,which is an important strategy to achieve sufficient oxygen evolution reaction(OER)performance in AEMWEs.Herein,the ternary NiFeM(M:La,Mo)catalysts featured with distinct M-NiFe units and varying d-orbitals are reported in this work.Experimental and theoretical calculation results reveal that the doping of La leads to optimized hybridization between d orbital in NiFeM and 2p in oxygen,resulting in enhanced adsorption strength of oxygen intermediates,and reduced rate-determining step energy barrier,which is responsible for the enhanced OER performance.More critically,the obtained NiFeLa catalyst only requires 1.58 V to reach 1 A cm^(−2) in an anion exchange membrane electrolyzer and demonstrates excellent long-term stability of up to 600 h.
基金financially supported by the National Natural Science Foundation of China(No.22209049)Natural Science Foundation of Guangdong Province(No.2023A1515012804)Science and Technology Program of Guangzhou(No.2023A04J0674)。
文摘The oxygen evolution reaction(OER)has received widespread attention as an anodic reaction in various key electrochemical processes such as water splitting,carbon dioxide electroreduction,and ammonia electrosynthesis.Therefore,there is an urgent need for efficient non-precious OER electrocatalysts to reduce the energy consumption and cost of these processes.NiFe layered double hydroxides(LDHs)with tunable electronic structure properties exhibit excellent OER intrinsic activity.However,their low electrical conductivity and tendency to agglomerate during electrocatalysis hinder their performance in OER.Herein,benefiting from the attraction of abundant negatively charged groups on the MXene surface towards Ni^(2+)and Fe^(3+),a heterostructure of highly conductive Mo_(2)CT_(x)MXene and NiFe alloy/LDH composite was prepared using a simple in-situ growth strategy.Combining experimental results and theoretical calculations,it is revealed that Mo_(2)CT_(x)MXene,as a substrate,significantly improves the OER performance of the NiFe-based catalyst by enhancing the electrical conductivity,mitigating the agglomeration,accelerating the oxidation and tuning the electronic structure.Consequently,in 1 M KOH electrolyte,the overpotential required to reach an OER current density of 10 mA cm^(-2)is only 230 mV,and the catalyst maintains high stability even after 3000 cyclic voltammetry cycles.This work expands the application of Mo_(2)CT_(x)MXene in electrocatalysis,and provides useful experience for the regulation of LDH-based electrocatalysts.
基金supported by the Shandong Natural Science Fund (No.ZR2020KB010)the Fundamental Research Funds for the Central Universities (No.22CX 07010A)。
文摘Reducing the cost and improving the electrocatalytic activity are the key to developing high efficiency electrocatalysts for oxygen evolution reaction(OER).Here,bimetallic NiFe-based metal-organic framework(MOF)was prepared by solvothermal method,and then used as precursor to prepare NiFe-based MOF-derived materials by pyrolysis.The effects of different metal ratios and pyrolysis temperatures on the sample structure and OER electrocatalytic performance were investigated and compared.The experimental results showed that when the metal molar ratio was Fe:Ni=1:5 and the pyrolysis temperature was 450℃,the sample(FeNi_(5)-MOF-450)exhibits a composite structure of Ni Fe_(2)O_(4)/FeNi_(3)/C and owns the superior electrocatalytic activity in OER.When the current density is 100 mA·cm^(-2),the overpotential of the sample was 377 mV with Tafel slope of 56.2 mV·dec^(-1),which indicates that FeNi_(5)-MOF-450 exhibits superior electrocatalytic performance than the commercial RuO_(2).Moreover,the long-term stability of FeNi_(5)-MOF-450 further promotes its development in OER.This work demonstrated that the regulatory methods such as component optimization can effectively improve the OER catalytic performance of NiFe-based MOF-derived materials.
