Acid etching engineering enhances the activity of oxygen evolution reaction in high entropy perovskite oxide

Perovskite oxide catalysts are gaining increasing attention for alkaline oxygen evolution reaction (OER) because of their stable crystal structures and inexpensive raw material sources. However, the low conductivity and the low intrinsic catalytic activity in perovskite oxides limit their performance in alkaline OER. Herein, we develop an acid-etched La 0.7 Sr 0.3 Ni 0.2 Co 0.2 Mn 0.2 Fe 0.2 Ru 0.2 O 3-δ perovskite oxide (H + -LSE x O) catalyst based on high entropy strategy and acid treatment engineering. Experimental characterization results indicate that the molar ratio of A-site atoms to B-site atoms (A/B) decreased significantly due to the partial inactive Sr atoms in H + -LSE x O are etched away. Electrochemical testing indicates that the current density of H + -LSE x O can reach 10 mA cm −2 only at an overpotential of 270 mV, which is comparable to the performance of the currently reported highly active OER catalysts (La 0.75 Eu 0.25 FeO 3 mesoporous nanosheets , Ni and Nd co-doped Co 3 O 4 spinel nanosheets). This work emphasizes the synergistic effect of acid treatment engineering to promote the exposure of B-site active sites and high-entropy strategy to regulate the electronic structure of B-site atoms in optimizing the OER performance of perovskite oxides. • An acid treatment strategy for high entropy perovskite oxide LSE x O. • H + -LSE x O's surface exhibits a considerable drop in the inactive Sr content. • XPS indicates that electron transfer occurs between B-site atoms in H + -LSE x O. • H + -LSE x O exhibits an excellent and stable OER performance.