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 Ti3C2Tx 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 || RuO2 combination (1.68 V).