Non-metal/metalloid modification of perovskite oxide enables lattice oxygen participation in accelerating oxygen evolution activity

Abstract

Perovskite oxides, with structural and compositional flexibility, have been extensively used as electrocatalysts in alkaline solutions for the oxygen evolution reaction (OER) which is a key factor in determining the overall efficiency of metal-air batteries or hydrogen evolution from electrochemical water splitting. The cation-doping approach is widely used to generate novel perovskite oxides with boosted electrocatalytic activity, while non-metal and metalloid modifications have received far less attention. Herein, we show a simple non-metal/metalloid alteration method to make efficient OER electrocatalysts with low overpotential and good stability. The developed SrCo0.95M0.05O3−δ (M = P, S, and Si) catalysts exhibit greatly improved OER activity and stability in comparison to the pristine hexagonal SrCoO3−δ. SrCo0.95Si0.05O3−δ achieves the lowest OER overpotential of 0.41 V at 10 mA cmdisk−2 and the lowest Tafel slope of 63 mV dec−1, while SrCoO3−δ exhibits 0.46 V and 95 mV dec−1 under identical conditions. SrCo0.95Si0.05O3−δ further demonstrates improved stability when compared to SrCoO3−δ. The creation of a stable cubic perovskite structure with an increased amount of oxygen vacancy facilitates oxygen diffusivity, thus maximizing the lattice oxygen participation. Furthermore, the surface evolution and the enhanced room-temperature electrical conductivity jointly contribute to the improvement of the electrocatalytic OER activity of SrCo0.95M0.05O3−δ. Our present findings offer a simple and viable strategy for creating highly efficient perovskites for OER.