Fabrication of nanocrystalline high-entropy oxide CoNiFeCrMnOₓ thin film electrodes by dip-coating for oxygen evolution electrocatalysis

The variation of calcination conditions allows for adjusting the oxidation states and coordination sites of near-surface elements in sol–gel-derived high-entropy oxides. Optimized synthesis conditions resulted in fabrication of nanocrystalline CoNiFeCrMnOₓ thin films with 1–2 nm pores, showing low OER overpotentials of 258 mV vs. RHE at 10 mA cm⁻².