Spinel-type ternary multimetal hybrid oxides with porous hierarchical structure grown on Ni foam as large-current-density water oxidation electrocatalyst

Transition metal oxides have been proved to be stable oxygen evolution reaction (OER) catalysts under alkaline conditions. However, their single component limits further improvement of elecatalytic activity. In this aspect, spinel oxides with adjustable composition show promising advantages. Herein, we report a spinel-type ternary multimetal hybrid oxides Co-doped NiO-Fe3O4@NiCo2O4 with porous hierarchical architecture grown on Ni foam. The obtained electrocatalyst has excellent electrocatalytic performance for OER 1 M KOH solution, which only needs overpotential of 280 mV to reach 10 mA cm−2. In practical industrial electrolyte (30 wt% KOH solution), this material just requires overpotential of 250 mV to reach a large-current-density of 1000 mA cm−2. Such superior high OER catalytic performance of this material should be related to the synergistic effect between metal elements of Ni, Co and Fe with intrinsically high OER activities; Hierarchical architecture exposes more catalytically active sites. Spinel oxides arrays with high conductivity can be used as fast electron transport pathways to effectively reduce resistance and thus improve catalytic activity. The unique hierarchical porous structure endows the catalyst with high mass transfer mobility. This work provides a new way to exploit spinel oxides OER electrocatalysts with high activity and stability. Such high activity and robust stability in concentrated KOH solution make it can be applied in commercial industrial electrolyzers.