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In this work, we have investigated the effect of oxygen vacancies on the surface composition, electronic structure, and oxygen evolution reaction (OER) performance of LaNiO 3 . The results show that the OER performance of LaNiO 3 can be improved both by decreasing the oxygen partial pressure during film growth and annealing the thin film in a H 2 atmosphere. X-ray photoemission spectroscopy (XPS) shows a significant increase in the Ni:La ratio on the LaNiO 3 surface after the introduction of oxygen defects, especially after H 2 treatment, where the Ni:La ratio reaches 3.5:1. The presence of oxygen vacancies leads to the aggregation of Ni on the surface of LaNiO 3, which plays a crucial role in enhancing the OER performance of LaNiO 3 . In addition, the OER activity of both LaNiO 3 and oxygen vacancy rich LaNiO 3 decreases upon cyclic voltammetry (CV) between 1.0 and 1.5 V versus the RHE with an increase in the cycle number. XPS results reveal that the CV treatments lead to a decrease in the Ni concentration at the LaNiO 3 surface, which is an important factor for the decrease in the OER performance of LaNiO 3 as well as oxygen vacancy rich LaNiO 3 .
Tian et al. (Thu,) studied this question.