Tuning the Electronic Structure of LaNiO3 through Alloying with Strontium to Enhance Oxygen Evolution Activity.

Jishan Liu,Endong Jia,Xu He,Eric Bousquet,Mark E Bowden,Xinmao Yin,Scott A Chambers,Hua Zhou,Kelsey A Stoerzinger,Andrew T S Wee,Le Wang,Chi Sin Tang,Yingge Du

doi:10.1002/advs.201901073

Abstract

The perovskite oxide LaNiO3 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 LaNiO3 films (La1− xSrxNiO3) significantly enhances the oxygen evolution reaction (OER) activity, resulting in performance at x = 0.5 comparable to the state‐of‐the‐art catalyst Ba0.5Sr0.5Co0.8Fe0.2O3− 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 La1− xSrxNiO3. This alloying step strengthens Ni 3d–O 2p hybridization and decreases the charge transfer energy, which in turn accounts for the enhanced OER activity.

Highlights

The perovskite oxide LaNiO3 is a promising oxygen electrocatalyst for renewable energy storage and conversion technologies
By combining X-ray photoemission spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) with density functional theory (DFT) calculations, we show that increasing the Sr mole fraction in LSNO system induces an upward shift of the O 2p bands relative to the Fermi level, strengthening Ni 3d–O 2p hybridization, and decreasing ∆, which accounts for the enhanced oxygen evolution reaction (OER) activity
The Ni 3d–O 2p hybridization is primarily controlled by ∆, while the transfer integral has a weaker influence.[36]

Summary

Introduction

The perovskite oxide LaNiO3 is a promising oxygen electrocatalyst for renewable energy storage and conversion technologies. By combining X-ray photoemission spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) with density functional theory (DFT) calculations, we show that increasing the Sr mole fraction in LSNO system induces an upward shift of the O 2p bands relative to the Fermi level, strengthening Ni 3d–O 2p hybridization, and decreasing ∆, which accounts for the enhanced OER activity.

Results

Conclusion