Amorphous Ni-Fe double hydroxide hollow nanocubes enriched with oxygen vacancies as efficient electrocatalytic water oxidation catalysts.

In this study, we present an ingenious design of Fe-modulated nickel hydroxide hollow nanocubes with a systematically engineered structure. The Ni0.75Fe0.25(OH)x sample exhibits good O2 evolution activity, which should be attributed to electronic modulation and abundant oxygen vacancies. Based on Pourbaix slope analysis, a two proton-one electron transfer is discovered in the amorphous Ni0.75Fe0.25(OH)x catalyst. Ni0.75Fe0.25(OH)x exhibits an enhanced performance for the electrocatalytic OER with a low overpotential of 310 mV at a current density of 10 mA cm-2.