Enhanced Oxygen Evolution Electrocatalysis in Strained A-Site Cation Deficient LaNiO Perovskite Thin Films

As the BO octahedral structure in perovskite oxide is strongly linked with electronic behavior, it is actively studied for various fields such as metal-insulator transition, superconductivity, and so on. However, the research about the relationship between water-splitting activity and BO structure is largely lacking. Here, we report the oxygen evolution reaction (OER) of LaNiO (LNO) by changing the NiO structure using compositional change and strain. The 5 atom % La deficiency in LNO resulted in an increase of the Ni-O-Ni bond angle and an expansion of bandwidth, enhancing the charge transfer ability. In-plane compressive strain derives the higher d orbital occupancy, leading to suitable metal-oxygen bond strength for OER. Because of the synergistic effect of A-site deficiency and compressive strain, the overpotential (η) of compressively strained LNO film is reduced to 130 mV at = 30 μA/cm compared with nonstrained LNO (η = 280 mV), indicating a significant enhancement in OER.