Electrocatalytic oxygen evolution reaction on LaNiO3 with tunable oxygen content under dual magnetic and light fields

Abstract

Vacancy and strain engineering have been identified as effective approaches for modulating the oxygen evolution reaction (OER) activity of electrocatalysts. Applying external fields like magnetic and light fields to electrocatalysts is also a potential approach to enhance the OER activity. However, the influence of the dual magnetic and light fields on the OER performance of electrocatalysts subjected to both vacancy and strain engineering remains unexplored. Herein, we rationally prepared epitaxial single-crystal LaNiO₃ (LNO) thin films as model electrocatalysts on LaAlO₃ (LAO) substrates under different oxygen pressures via pulsed laser deposition (PLD), obtaining LNO thin films with compressive strain and tunable oxygen contents. It is found that a volcano-shaped relationship exists between the OER activity and the oxygen content. This relationship originates from the synergistic modulation of both the Ni²⁺/Ni³⁺ ratio and the d-band center position in the LNO thin films. Furthermore, the LNO thin films exhibit a higher OER activity under dual magnetic and light fields compared to those under no external fields, irrespective of their oxygen content. The enhanced OER activity under dual magnetic and light fields primarily stems from the generation of photogenerated electron–hole pairs and the formation of triplet-state oxygen species, collectively reducing the energy barrier for the OER process.