A dual-site doping strategy for developing efficient perovskite oxide electrocatalysts towards oxygen evolution reaction

Perovskite-type ABO₃ transition metal oxides are promising electrocatalysts for oxygen evolution reaction (OER), but still suffer from insufficient activities. Traditional efforts are mainly based on a single-site doping of heteroatom ions into either B-sites or O-sites of the ABO₃ structures. Here we propose a dual-site doping strategy by simultaneous incorporation of iodine cations and anions into the B-sites and O-sites of ABO₃ perovskite oxides, respectively. Consequently, both activated B-site transition metals with optimal e_g orbital occupancy and large amount of active oxygen species were achieved for remarkably improved OER activities. Using this approach, significantly improved OER activities are achieved in some representative perovskite oxides, including Ba_0.5Sr_0.5(Co_0.8Fe_0.2)_0.9O_3–δ (BSCF), SrCo_0.9O_3−δ (SCO) and SrNi_0.9O_3−δ (SNO). Specifically, the iodine dual-site doped BSCF boosts a small overpotential of 290 mV at 10 mA cm⁻² and a small Tafel slope of 53 mV dec⁻¹, which is about 130 mV and almost half times lower than that of pristine BSCF, respectively. Besides, this general dual-site doping strategy can also realize scale-up synthesis and achieve a gram-scale production. Our findings show a unique doping strategy to design efficient perovskite oxide electrocatalysts beyond the conventional approaches.