NiFe(oxy)hydroxides nanosheets were synthesized on nickel foams via co-precipitation and electrochemical activation. It is found that the phosphate precursors(Na_(3)PO_(4), Na_(2)HPO_(4)and NaH_(2)PO_(4)) have diverse...NiFe(oxy)hydroxides nanosheets were synthesized on nickel foams via co-precipitation and electrochemical activation. It is found that the phosphate precursors(Na_(3)PO_(4), Na_(2)HPO_(4)and NaH_(2)PO_(4)) have diverse effects on the morphology and thus the oxygen evolution reaction activity of the formed final catalysts. The resulting NiFe(oxy)hydroxides nanosheets prepared with Na_(2)HPO_(4)demonstrate a low overpotential of 205 m V to achieve a current density of 50 mA/cm^(2) with a Tafel slope down to 30 mV/dec in 1 mol/L KOH, and remain stable for 20 h during stability test.展开更多
The development of highly efficient and cost-effective electrode materials for catalyzing the oxygen evolution reaction(OER)is crucial for water splitting technology.The increase in the number of active sites by tunin...The development of highly efficient and cost-effective electrode materials for catalyzing the oxygen evolution reaction(OER)is crucial for water splitting technology.The increase in the number of active sites by tuning the morphology and structure and the enhancement of the reactivity of active sites by the incorporation of other components are the two main strategies for the enhancement of their catalytic performance.In this study,by combining these two strategies,a unique three-dimensional nanoporous Fe-Co oxyhydroxide layer coated on the carbon cloth(3D-FeCoOOH/CC)was successfully synthesized by in situ electro-oxidation methods,and directly used as a working electrode.The electrode,3D-FeCoOOH/CC,was obtained by the Fe doping process in(NH4)2Fe(SO4)2,followed by continuous in situ electro-oxidization in alkaline medium of“micro go chess piece”arrays on the carbon cloth(MCPAs/CC).Micro characterizations illustrated that the go pieces of MCPAs/CC were completely converted into a thin conformal coating on the carbon cloth fibers.The electrochemical test results showed that the as-synthesized 3D-FeCoOOH/CC exhibited enhanced activity for OER with a low overpotential of 259 mV,at a current density of 10 mA cm^–2,and a small Tafel slope of 34.9 mV dec^–1,as well as superior stability in 1.0 mol L^–1 KOH solution.The extensive analysis revealed that the improved electrochemical surface area,conductivity,Fe-Co bimetallic composition,and the unique 3D porous structure together contributed to the enhanced OER activity of 3D-FeCoOOH/CC.Furthermore,the synthetic strategy applied in this study could be extended to fabricate a series of Co-based electrode materials with the dopant of other transition elements.展开更多
The low-cost and high-capacity metal oxides/oxyhydroxides possess great merits as anodes for lithium-ion batteries(LIBs)with high energy density.However,their commercialization is greatly hindered by insufficient rate...The low-cost and high-capacity metal oxides/oxyhydroxides possess great merits as anodes for lithium-ion batteries(LIBs)with high energy density.However,their commercialization is greatly hindered by insufficient rate capability and cyclability.Rational regulations of metal oxides/oxyhydroxides with hollow geometry and disordered atomic frameworks represent efficient ways to improve their electrochemical properties.Herein,we propose a fast alkalietching method to realize the in-situ fabrication of iron oxyhydroxide with one-dimensional(1D)hierarchical hollow nanostructure and amorphous atomic structure from the iron vanadate nanowires.Benefiting from the improved electron/ion kinetics and efficient buffer ability for the volumetric change during the electro-cycles both in nanoscale and atomic level,the graphene-modified amorphous hierarchical FeOOH nanotubes(FeOOH-NTs)display high rate capability(~650 mA h g^−1 at 2000 mA g^−1)and superior long-term cycling stability(463 mA h g^−1 after 1800 cycles),which represents the best cycling performance among the reported FeOOH-based materials.More importantly,the selective dissolutionregrowth mechanism is demonstrated based on the time tracking of the whole transition process,in which the dissolution of FeVO4 and the in-situ selective re-nucleation of FeOOH during the formation of FeOOH-NTs play the key roles.The present strategy is also a general method to prepare various metal(such as Fe,Mn,Co,and Cu)oxides/oxyhydroxides with 1D hierarchical nanostructures.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 11904411, 52072308)the Fundamental Research Funds for the Central Universities, China (Nos. 3102021MS0404, 3102019JC001)。
文摘NiFe(oxy)hydroxides nanosheets were synthesized on nickel foams via co-precipitation and electrochemical activation. It is found that the phosphate precursors(Na_(3)PO_(4), Na_(2)HPO_(4)and NaH_(2)PO_(4)) have diverse effects on the morphology and thus the oxygen evolution reaction activity of the formed final catalysts. The resulting NiFe(oxy)hydroxides nanosheets prepared with Na_(2)HPO_(4)demonstrate a low overpotential of 205 m V to achieve a current density of 50 mA/cm^(2) with a Tafel slope down to 30 mV/dec in 1 mol/L KOH, and remain stable for 20 h during stability test.
基金supported by the Taishan Scholar Program of Shandong (ts201511027)the Natural Science Foundation of Shandong Province (2018GGX102030)+1 种基金support from the “Hundred Talent Program” of Chinese academy of Sciences (CAS) (RENZI[2015] 70HAO, Y5100619AM),DICP and QIBEBT (UN201804),Dalian National Laboratory For Clean Energy (DNL),CASResearch Innovation Fund (QIBEBT SZ201801)~~
文摘The development of highly efficient and cost-effective electrode materials for catalyzing the oxygen evolution reaction(OER)is crucial for water splitting technology.The increase in the number of active sites by tuning the morphology and structure and the enhancement of the reactivity of active sites by the incorporation of other components are the two main strategies for the enhancement of their catalytic performance.In this study,by combining these two strategies,a unique three-dimensional nanoporous Fe-Co oxyhydroxide layer coated on the carbon cloth(3D-FeCoOOH/CC)was successfully synthesized by in situ electro-oxidation methods,and directly used as a working electrode.The electrode,3D-FeCoOOH/CC,was obtained by the Fe doping process in(NH4)2Fe(SO4)2,followed by continuous in situ electro-oxidization in alkaline medium of“micro go chess piece”arrays on the carbon cloth(MCPAs/CC).Micro characterizations illustrated that the go pieces of MCPAs/CC were completely converted into a thin conformal coating on the carbon cloth fibers.The electrochemical test results showed that the as-synthesized 3D-FeCoOOH/CC exhibited enhanced activity for OER with a low overpotential of 259 mV,at a current density of 10 mA cm^–2,and a small Tafel slope of 34.9 mV dec^–1,as well as superior stability in 1.0 mol L^–1 KOH solution.The extensive analysis revealed that the improved electrochemical surface area,conductivity,Fe-Co bimetallic composition,and the unique 3D porous structure together contributed to the enhanced OER activity of 3D-FeCoOOH/CC.Furthermore,the synthetic strategy applied in this study could be extended to fabricate a series of Co-based electrode materials with the dopant of other transition elements.
基金This work was supported by the National Key Research and Development Program of China(2017YFE0127600,2016YFA0202600)the Program of Introducing Talents of Discipline to Universities(B17034)+3 种基金the National Natural Science Foundation of China(51521001 and 51602239)the National Natural Science Fund for Distinguished Young Scholars(51425204)Hubei Provincial Natural Science Foundation(2016CFB267)the Fundamental Research Funds for the Central Universities(WUT:2017-YB-001).
文摘The low-cost and high-capacity metal oxides/oxyhydroxides possess great merits as anodes for lithium-ion batteries(LIBs)with high energy density.However,their commercialization is greatly hindered by insufficient rate capability and cyclability.Rational regulations of metal oxides/oxyhydroxides with hollow geometry and disordered atomic frameworks represent efficient ways to improve their electrochemical properties.Herein,we propose a fast alkalietching method to realize the in-situ fabrication of iron oxyhydroxide with one-dimensional(1D)hierarchical hollow nanostructure and amorphous atomic structure from the iron vanadate nanowires.Benefiting from the improved electron/ion kinetics and efficient buffer ability for the volumetric change during the electro-cycles both in nanoscale and atomic level,the graphene-modified amorphous hierarchical FeOOH nanotubes(FeOOH-NTs)display high rate capability(~650 mA h g^−1 at 2000 mA g^−1)and superior long-term cycling stability(463 mA h g^−1 after 1800 cycles),which represents the best cycling performance among the reported FeOOH-based materials.More importantly,the selective dissolutionregrowth mechanism is demonstrated based on the time tracking of the whole transition process,in which the dissolution of FeVO4 and the in-situ selective re-nucleation of FeOOH during the formation of FeOOH-NTs play the key roles.The present strategy is also a general method to prepare various metal(such as Fe,Mn,Co,and Cu)oxides/oxyhydroxides with 1D hierarchical nanostructures.
