Nanostructured NiCo@NiCoOx core-shell layer as efficient and robust electrocatalyst for oxygen evolution reaction

•(NH4)2SiF6 is used as silicon source to electrodeposit NiCo-SiO2 composite film.•Nanostructured NiCo@NiCoOx core-shell layer is obtained after the etching of SiO2 template.•An overpotential of 337 mV is needed to deliver a current density of 100 mA cm−2.•The good electrical conductivity in the core and high catalytic activity on the shell result in the high OER performance.

A nanostructured NiCo@NiCoOx core-shell layer for oxygen evolution reaction in alkaline solution was prepared. Firstly, a NiCo-SiO2 composite film was electro-codeposited from a solution containing (NH4)2SiF6, NiSO4, and CoSO4. Then the as-prepared composite layer was underwent consecutive CV scans in concentrated alkaline solution. During this process, the SiO2 template was etched and the NiCo component was activated leading to the generation of a NiCoOx shell. Results shown that this nanostructured NiCo@NiCoOx core-shell layer can provide a current density of 100 mA cm−2 in 1.0 M KOH at a low overpotential of 337 mV and exhibits good stability towards water oxidation. The excellent OER performance is enabled with the unique metal-oxide/hydroxide core-shell structure, which allows high electrical conductivity in the core and high catalytic activity on the shell.

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