Activating surface atoms of high entropy oxides for enhancing oxygen evolution reaction

High entropy oxides (HEOs) have attracted extensive attention of researchers due to their remarkable properties. The electrocatalytic activity of electrocatalysts is closely related to the reactivity of their surface atoms which usually shows a positive correlation. Excellenet stability of HEOs leads to their surface atoms with relative poor reactivity, limiting the applications for electrocatalysis. Therefore, it is significant to activate surface atoms of HEOs. Constructing amorphous structure, introducing oxygen defects and leaching are very effective strategies to improve the reactivity of surface atoms. Herein, to remove chemical inert, low-crystallinity (Fe, Co, Ni, Mn, Zn)3O4 (HEO-Origin) nanosheets with abundant oxygen vacancies was synthesized, showing an excellent catalytic activity with an overpotential of 265 mV at 10 mA/cm2, which outperforms as-synthesized HEO-500°C-air (335 mV). The excellent catalytic performance of HEO-Origin can be attributed to high activity surface atoms, the introduction of oxygen defects efficiently altered electron distribution on the surface of HEO-Origin. Apart from, HEO-Origin also exhibits an outstanding electrochemical stability for oxygen evolution reaction (OER).