Al3+ leaching induced Co4+ on CoFeAl layered double hydroxide for enhanced oxygen evolution reaction

Transition metal Co-based materials such as layered double hydroxides (LDHs) are recognized as the pre-catalysts that will undergo the electrochemical reconstruction under oxygen evolution reaction (OER) conditions, in which the formed high-valent Co4+ can offer high intrinsic activity. However, the controllable formation of highly active Co4+ species still remains challenging. Herein, we show that the leaching of Al3+ after OER activation successfully induces the high-valent Co4+ formed on CoFeAl LDH (CFA0.8-LDH/NF–200CV), which is confirmed by a series of physical characterization and electrochemical measurements. The reconstructed electrocatalyst CFA0.8-LDH/NF–200CV presents excellent OER performance with an overpotential of 222 mV at 10 mA cm−2 and a small Tafel slope of 25.4 mV dec−1. This work may enlighten the surface reconstruction and activity promotion with leachable cations to induce high-valent metal active sites of other electrocatalysts.