Interfacial engineering of a tri-phase CoFe/CoFeOx/Co–Fe3O4 electrocatalyst for promoting the oxygen evolution reaction

Obtaining highly efficient and structurally stable electrocatalysts for electrocatalytic oxygen evolution reactions (OERs) at anodes by a simple and feasible strategy remains challenging for achieving hydrogen production with low-energy consumption. Herein, we successfully constructed a tri-phase interfacial structure of CoFe alloy/CoFe oxide/cobalt-doped iron oxide (denoted as CoFe/CoFeOx/Co–Fe3O4) as a highly efficient and low-cost OER electrocatalyst by a one-step chemical bath deposition approach. The tri-phase interfacial structure was achieved by controlling the dosage of reductants/oxidants and tuning the proportion of Co/Fe salts. The as-prepared CoFe/CoFeOx/Co–Fe3O4 not only delivered a remarkable OER activity, i.e., a low overpotential of 291 mV at 10 mA cm−2 and a small Tafel slope of 47.8 mV dec−1, but also exhibited a decent stability for a long-term electrolysis. To unveil the catalytic mechanism, two reasonable aspects of adsorption regulation of oxygenating intermediates and interfacial charge transfer at electrodes/electrolytes were predictively proposed.