Titanium dioxide induced nickel-iron alloy-based precatalyst towards efficient and durable oxygen evolution reaction

Highly active and stable electrocatalysts are essential to facilitate the oxygen evolution reaction (OER) during alkaline water splitting. Herein, a titanium dioxide supported NiFe-based OER electrocatalyst (NiFe/TiO ₂) was developed through simple impregnation reduction method. The introduction of TiO ₂ support not only enhances the catalyst stability, but also induces the formation of NiFe alloy pre-catalyst layer on the oxide surface. In situ Raman revealed that the NiFe alloy was partially transformed into highly active NiOOH species in OER process. In situ infrared and theoretical calculations confirm the promoted formation of *OOH intermediate on NiFe/TiO ₂ surface and thus accelerates the OER. The NiFe/TiO ₂ catalyst achieves excellent OER activity delivering 10 mA cm ⁻² at low overpotential of 240 mV in 1.0 M KOH. The anion exchange membrane water electrolyzer with NiFe/TiO ₂ achieves 500 mA cm ⁻² with cell voltage of 1.72 V, and good stability is maintained for 300 h. This study advances the effort of developing efficient and durable alkaline OER catalysts.