Tuning the Electronic Structure of LaNiO(3) through Alloying with Strontium to Enhance Oxygen Evolution Activity

The perovskite oxide LaNiO(3) is a promising oxygen electrocatalyst for renewable energy storage and conversion technologies. Here, it is shown that strontium substitution for lanthanum in coherently strained, epitaxial LaNiO(3) films (La(1−) (x)Sr(x)NiO(3)) significantly enhances the oxygen evolution reaction (OER) activity, resulting in performance at x = 0.5 comparable to the state‐of‐the‐art catalyst Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3−) (δ). By combining X‐ray photoemission and X‐ray absorption spectroscopies with density functional theory, it is shown that an upward energy shift of the O 2p band relative to the Fermi level occurs with increasing x in La(1−) (x)Sr(x)NiO(3). This alloying step strengthens Ni 3d–O 2p hybridization and decreases the charge transfer energy, which in turn accounts for the enhanced OER activity.