Enhanced Oxygen Evolution Electrocatalysis in Strained A-Site Cation Deficient LaNiO<sub>3</sub> Perovskite Thin Films
Min‐Ju Choi, Taemin Ludvic Kim, Jeong Kyu Kim, Tae Hyung Lee, Sol A Lee, Changyeon Kim, Kootak Hong, Chung Wung Bark, Kyung‐Tae Ko, Ho Won Jang
Abstract
As the BO6 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 BO6 structure is largely lacking. Here, we report the oxygen evolution reaction (OER) of LaNiO3 (LNO) by changing the NiO6 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 dz2 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 L0.95NO film is reduced to 130 mV at j = 30 μA/cm2 compared with nonstrained LNO (η = 280 mV), indicating a significant enhancement in OER.