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-& delta; HEO with stable structure as well as large electrochemical surface area (ECSA) exhibits robust electrocatalytic activity towards both oxygen evolution reaction (OER, & eta;10 = 174 mV) and hydrogen evolution reaction (HER, & eta;10 = 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 structurestable HEOs for efficient electrocatalytic applications.

Automated summary

High-entropy oxides (HEOs), as a common type of high-entropy materials, have limited active sites due to their high crystallization. In this study, a surface activation strategy was proposed to enhance the electrocatalytic activity of HEOs by introducing abundant surface oxygen vacancies using resin templating and temperature regulation. The modulated (Fe0.27Ni0.35Co0.24Cr0.10Mn0.04)2O3-δ HEO exhibited a stable structure, large electrochemical surface area, and robust electrocatalytic activity towards both oxygen and hydrogen evolution reactions. The assembled water splitting cell achieved a low voltage of 1.55 V to achieve 10 mA cm-2 current density, outperforming commercial noble metal electrocatalysts. This work provides a new approach for designing structure-stable HEOs for efficient electrocatalytic applications.