Magnesium incorporation activates perovskite cobaltites toward efficient and stable electrocatalytic oxygen evolution

Abstract

Cobalt-rich perovskite oxides play a paramount role in catalyzing oxygen evolution reaction (OER) on account of their acceptable intrinsic activity but are still challenging due to the high costs and undesired stability. In response to the defects, herein, the Mg-incorporated perovskite cobaltite SrCo_0.6Fe_0.3Mg_0.1O_3−δ (SCFM-0.1) is proposed as a novel earth-abundant and durable OER electrocatalyst. A well-consolidated cubic-symmetry structure and more active oxygen intermediates are enabled upon Mg substitution. Hence, the optimized SCFM-0.1 perovskite oxide achieves prominent OER electrocatalytic performance, that is, a low overpotential of only 320 mV at 10 mA cm⁻², a small Tafel slope of 65 mV dec⁻¹, as well as an outstanding durability within 20 h, substantially outperforming that of the pristine SrCo_0.7Fe_0.3O_3−δ and benchmark Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ and IrO₂ catalysts. The strong pH-dependent behavior associated with lattice oxygen activation mechanism for SCFM-0.1 catalyst is also confirmed. This work paves a unique avenue to develop cost-effective and robust perovskite cobaltites for efficient OER electrocatalysis.