At room temperature and in the presence of trace EDTA, the formation of δ-FeOOH was studied by the rapid oxidation of Fe（OH）2 suspension with O2. The structural and morphological changes were characterized by vario...At room temperature and in the presence of trace EDTA, the formation of δ-FeOOH was studied by the rapid oxidation of Fe（OH）2 suspension with O2. The structural and morphological changes were characterized by various techniques such as XRD, FTIR and TEM. γ-FeOOH and （δ-FeOOH） formed simutaneously in the early period of oxidation. But as the rate of mass transfer was in equilibrium, trace （γ-FeOOH） vanished gradually. Accordingly, pure phase δ-FeOOH was obtained. At the same time, critical amount ratio K of EDTA to Fe2+ was verified. The experiments show that the reactivity, rate of the oxidizing agent and pH of the initial medium were important factors for the formation of pure phase （δ-FeOOH）. Under the auxiliary effect of EDTA, the reactivity of O2 was nearly improved to that of H2O2. And the process of the oxidation that Fe（OH）2 suspension was oxidized by O2 under that condition was discussed.展开更多
Development of efficient non-precious catalysts for seawater electrolysis is of great significance but challenging due to the sluggish kinetics of oxygen evolution reaction(OER)and the impairment of chlorine electroch...Development of efficient non-precious catalysts for seawater electrolysis is of great significance but challenging due to the sluggish kinetics of oxygen evolution reaction(OER)and the impairment of chlorine electrochemistry at anode.Herein,we report a heterostructure of Ni_(3)S_(2)nanoarray with secondary Fe-Ni(OH)_(2)lamellar edges that exposes abundant active sites towards seawater oxidation.The resultant Fe-Ni(OH)_(2)/Ni_(3)S_(2)nanoarray works directly as a free-standing anodic electrode in alkaline artificial seawater.It only requires an overpotential of 269 mV to afford a current density of 10 mA·cm^(-2)and the Tafel slope is as low as 46 m V·dec^(-1).The 27-hour chronopotentiometry operated at high current density of 100 mA·cm^(-2)shows negligible deterioration,suggesting good stability of the Fe-Ni(OH)_(2)/Ni_(3)S_(2)@NF electrode.Faraday efficiency for oxygen evolution is up to〜95%,revealing decent selectivity of the catalyst in saline water.Such desirable catalytic performance could be benefitted from the introduction of Fe activator and the heterostructure that offers massive active and selective sites.The density functional theory(DFT)calculations indicate that the OER has lower theoretical overpotential than Cl_(2) evolution reaction in Fe sites,which is contrary to that of Ni sites.The experimental and theoretical study provides a strong support for the rational design of high-performance Fe-based electrodes for industrial seawater electrolysis.展开更多
Developing highly stable electrocatalysts under industry-compatible current densities(>500 mA cm^(-2))in an anion-exchange membrane water electrolyzer(AEMWE)is an enormous challenge for water splitting.Herein,based...Developing highly stable electrocatalysts under industry-compatible current densities(>500 mA cm^(-2))in an anion-exchange membrane water electrolyzer(AEMWE)is an enormous challenge for water splitting.Herein,based on the results of density function theory calculations,a dual heterogeneous interfacial structured NiSe/Fe-Ni(OH)_(2)catalyst was subtly designed and successfully prepared by electrodepositing Fe-doped Ni(OH)_(2)on NiSe-loaded nickel foam(NF).Fe doping-driven heterogeneous structures in NiSe/Fe-Ni(OH)_(2)markedly boost catalytic activity and durability at industrially compatible current densities in single hydrogen and oxygen evolution reactions under alkaline conditions.In particular,NiSe/Fe-Ni(OH)_(2)shows a negligible performance loss at 600 mA cm^(-2)at least 1,000 h for overall water splitting,a distinguished long-term durability acting as AEMWE electrodes at 600 mA cm^(-2)and 1 A cm^(-2)at 85℃for at least 95 h.Owing to Fe doping-induced strong synergetic effect between Ni and Fe,dual heterostructure-promoted charge transfer and redistribution,abundant catalytic active sites,and improvement of stability and durability,a mechanism of Fe doping-driven heterogeneous interfacial structurepromoted catalytic performance was proposed.This study provides a successful example of theory-directed catalyst preparation and pioneers a creative strategy for industry-compatible water splitting at high current density.展开更多
文摘At room temperature and in the presence of trace EDTA, the formation of δ-FeOOH was studied by the rapid oxidation of Fe（OH）2 suspension with O2. The structural and morphological changes were characterized by various techniques such as XRD, FTIR and TEM. γ-FeOOH and （δ-FeOOH） formed simutaneously in the early period of oxidation. But as the rate of mass transfer was in equilibrium, trace （γ-FeOOH） vanished gradually. Accordingly, pure phase δ-FeOOH was obtained. At the same time, critical amount ratio K of EDTA to Fe2+ was verified. The experiments show that the reactivity, rate of the oxidizing agent and pH of the initial medium were important factors for the formation of pure phase （δ-FeOOH）. Under the auxiliary effect of EDTA, the reactivity of O2 was nearly improved to that of H2O2. And the process of the oxidation that Fe（OH）2 suspension was oxidized by O2 under that condition was discussed.
基金the National Natural Science Foundation of China(No.91963113).
文摘Development of efficient non-precious catalysts for seawater electrolysis is of great significance but challenging due to the sluggish kinetics of oxygen evolution reaction(OER)and the impairment of chlorine electrochemistry at anode.Herein,we report a heterostructure of Ni_(3)S_(2)nanoarray with secondary Fe-Ni(OH)_(2)lamellar edges that exposes abundant active sites towards seawater oxidation.The resultant Fe-Ni(OH)_(2)/Ni_(3)S_(2)nanoarray works directly as a free-standing anodic electrode in alkaline artificial seawater.It only requires an overpotential of 269 mV to afford a current density of 10 mA·cm^(-2)and the Tafel slope is as low as 46 m V·dec^(-1).The 27-hour chronopotentiometry operated at high current density of 100 mA·cm^(-2)shows negligible deterioration,suggesting good stability of the Fe-Ni(OH)_(2)/Ni_(3)S_(2)@NF electrode.Faraday efficiency for oxygen evolution is up to〜95%,revealing decent selectivity of the catalyst in saline water.Such desirable catalytic performance could be benefitted from the introduction of Fe activator and the heterostructure that offers massive active and selective sites.The density functional theory(DFT)calculations indicate that the OER has lower theoretical overpotential than Cl_(2) evolution reaction in Fe sites,which is contrary to that of Ni sites.The experimental and theoretical study provides a strong support for the rational design of high-performance Fe-based electrodes for industrial seawater electrolysis.
基金supported by the National Natural Science Foundation of China(22162025,22068037)the Youth Innovation Team of Shaanxi Universities+2 种基金the Open and Innovation Fund of Hubei Three Gorges Laboratory(SK232001)the Regional Innovation Capability Leading Program of Shaanxi(2022QFY07-03,2022QFY07-06)the Shaanxi Province Training Program of Innovation and Entrepreneurship for Undergraduates(S202210719108)。
文摘Developing highly stable electrocatalysts under industry-compatible current densities(>500 mA cm^(-2))in an anion-exchange membrane water electrolyzer(AEMWE)is an enormous challenge for water splitting.Herein,based on the results of density function theory calculations,a dual heterogeneous interfacial structured NiSe/Fe-Ni(OH)_(2)catalyst was subtly designed and successfully prepared by electrodepositing Fe-doped Ni(OH)_(2)on NiSe-loaded nickel foam(NF).Fe doping-driven heterogeneous structures in NiSe/Fe-Ni(OH)_(2)markedly boost catalytic activity and durability at industrially compatible current densities in single hydrogen and oxygen evolution reactions under alkaline conditions.In particular,NiSe/Fe-Ni(OH)_(2)shows a negligible performance loss at 600 mA cm^(-2)at least 1,000 h for overall water splitting,a distinguished long-term durability acting as AEMWE electrodes at 600 mA cm^(-2)and 1 A cm^(-2)at 85℃for at least 95 h.Owing to Fe doping-induced strong synergetic effect between Ni and Fe,dual heterostructure-promoted charge transfer and redistribution,abundant catalytic active sites,and improvement of stability and durability,a mechanism of Fe doping-driven heterogeneous interfacial structurepromoted catalytic performance was proposed.This study provides a successful example of theory-directed catalyst preparation and pioneers a creative strategy for industry-compatible water splitting at high current density.
