Surface Reconstruction of La_0.8Sr_0.2Co_0.8Fe_0.2O_3−δ for Superimposed OER Performance

Perovskites have become important OER electrocatalysts. Herein, as-prepared La0.8Sr0.2Co0.8Fe0.2O3-δ (LSCF-0) is chosen as a sample to exhibit the superimposed effect of surface reconstruction accompanied by reduction of Co3+ to Co2+ on the further improvement of its activity and stability. As-synthesized LSCF-0 perovskite is chemically treated by simply immersing in an aqueous solution of NaBH4 for 1.0 h at room temperature. The optimized LSCF (LSCF-2) owns an amorphous layer consisting of nanosized particles of ∼20 nm (vs smooth bulk crystalline surface for untreated LSCF), which exhibits superior OER performance to LSCF-0. LSCF-2 has an overpotential of 248 mV (10 mA cm-2) and a Tafel slope of 51 mV dec-1 (vs 355 mV and 76 mV dec-1 for LSCF-0 and 381 mV and 91 mV dec-1 for LCO) and an excellent cycle stability for 20 h running. This work supplies a new strategy to enhance OER performance through surface reconstruction of as-prepared perovskites.