Engineering High-Entropy Duel-Functional nanocatalysts with regulative oxygen vacancies for efficient overall water splitting

High-entropy materials (HEMs) have attracted growing attention in catalysis fields owing to their multielement synergy and tunable electronic configuration. As one of the commonest HEMs, high-entropy oxides (HEOs), however, are far from satisfactory in terms of their high crystallization with insufficient active sites. Herein, a surface activation strategy is proposed to engineer high-activity HEOs electrocatalysts in which ample surface oxygen vacancies (OVs) are imported by means of resin templating and temperature regulation. As a result, the modulated (Fe0.27Ni0.35Co0.24Cr0.10Mn0.04)2O3-δ HEO with stable structure as well as large electrochemical surface area (ECSA) exhibits robust electrocatalytic activity towards both oxygen evolution reaction (OER, η10 = 174 mV) and hydrogen evolution reaction (HER, η10 = 60 mV). Correspondingly, as-assembled water splitting cell only requires a low voltage of 1.55 V to achieve 10 mA cm−2 current density, far superior to that of 1.72 V using the commercial noble metal electrocatalysts. This work opens up a new avenue in designing structure-stable HEOs for efficient electrocatalytic applications.