Two orders of magnitude enhancement in oxygen evolution reactivity of La_0.7Sr_0.3Fe_1−xNi_xO_3−δ by improving the electrical conductivity

Developing highly efficient and robust electrocatalysts for oxygen evolution reaction (OER) is critical to renewable energy technologies. Here, we report an effective strategy to enhance the OER activity of a perovskite electrocatalyst through improving the electrical conductivity introduced by the structural transition. La_0.7Sr_0.3Fe_1−xNi_xO_3−δ (denoted as LSFN-x) with increasing Ni content is found to crystallize in a higher symmetry structure and exhibit improved OER catalytic performance. The optimized cubic LSFN-0.4 catalyst delivers a 90–times higher specific activity than its non-doped parent rhombohedral compound La_0.7Sr_0.3FeO_3−δ at an overpotential of 340 mV, with an overpotential of only 320 mV for 10 mA cm⁻² and a low Tafel slope of 35 mV dec⁻¹ in 0.1 M KOH, while maintaining excellent durability during 1000 continuous cycles and 50 h-water-splitting in a laboratory-scale electrolyzer. The enhanced OER catalytic performance of LSFN-0.4 is highly correlated with its increased conductivity as well as the increased oxygen vacancy concentration.