High‐Entropy Spinel Oxides‐Decorated MXene Nanoarchitectures for Efficient Methanol Oxidation‐Assisted Hydrogen Production

ABSTRACT The substitution of methanol oxidation reaction (MOR) for conventional oxygen evolution reaction (OER) in water electrolysis systems presents a promising strategy to enhance hydrogen production efficiency. Herein, we demonstrate this concept through the rational design of high‐entropy spinel oxide‐decorated Ti 3 C 2 T x MXene (HEO/MX) nanoarchitectures that simultaneously catalyze both hydrogen evolution reaction (HER) and selective methanol‐to‐formate conversion. The well‐dispersive high‐entropy spinel oxides afford numerous catalytically active centers as well as multiple electronic hybridizations, while the ultrathin MXene nanosheets enable the intimate interfacial interactions and guarantee a rapid electron transport rate. Accordingly, the newly‐developed HEO/MX hybrid nanoarchitecture exhibits optimized anodic MOR performance with an oxidation voltage of 1.53 V vs RHE (0.12 V lower than that of OER) to achieve a current density of 100 mA cm −2 , and simultaneously it requires a cathodic HER overpotential of 140 mV to achieve 10 mA cm −2 in alkaline medium. Strikingly, a coupled alkaline HER‐MOR electrolytic cell assembled with the bifunctional HEO/MX electrocatalyst requires only 1.59 V to derive a current density of 10 mA cm −2 , more competitive than that of conventional HER–OER system based on commercial Pt/C || RuO 2 combination (1.68 V).