Enhanced oxygen evolution reaction activity of oxygen-deficient perovskite catalysts with A-site defects boosted by self-assembled silver nanoparticles

To enhance the competitiveness of perovskite electrocatalysts in oxygen evolution reaction (OER), it is vital to improve its catalytic activity and durability while controlling costs. Herein, we report a composite electrocatalyst of Ag/Sr0<middle dot>8Ag0<middle dot>2Co0<middle dot>75Fe0<middle dot>25O3-delta, which was designed by integrating internal structure-engineering, A-site defect, and in-situ Ag segregation. This electrocatalyst demonstrates an excellent OER performance in an alkaline electrolyte, surpassing the catalytic activity and durability of commercial RuO2 electrocatalysts. Various characterization techniques as well as density functional theory (DFT) calculations were performed to elucidate the synergistic coupling effects of Sr0<middle dot>8Ag0<middle dot>2Co0<middle dot>75Fe0<middle dot>25O3-delta with Ag nanoparticles (NPs) in the OER process. The robust interface anchoring Ag NPs on Sr0<middle dot>8Ag0<middle dot>2Co0<middle dot>75Fe0<middle dot>25O3-delta perovskite can induce ligand effects and interparticle cooperation, thereby promoting electron transfer and ion migration during OER. Meanwhile, partial Ag+ forms Ag NPs contributing to the formation of A-site defects, which results in an increase of oxygen vacancies and induces lattice expansion. A-site defects can optimize the occupancy of e(g) orbitals close to unity for B-site transition metals, thereby greatly enhancing OER catalytic activity. This work highlights an effective strategy to enhance OER activity of perovskite electrocatalysts.