Compositional Engineering of Ti₃C₂Tx MXene-NiMoO₄ Hybrid Nanostructures for Enhanced Electrocatalytic Water Oxidation

A critical step in realizing the vision of green hydrogen through water splitting is to design oxygen evolution reaction (OER) catalysts that showcase a good balance of activity and stability. This work reports the compositional tuning of a NiMoO4 material and then the subsequent varying of Ti3C2T x MXene with the NiMoO4 hybrid nanostructures as OER catalysts in alkaline media. In this work, the optimum NiMoO4 hybrid catalyst retained good stability over 24 h of chronopotentiometry on industrial relevant supports (Ni Felt) with an overpotential value of ca. 339 mV at 100 mA cm-2. Operando Raman spectroscopy revealed that catalytically active β-NiOOH species are formed during OER in NiMoO4 at lower overpotentials than for pure NiO and that a higher amount of the β-NiOOH was found in the 5% MXene loading. The ICP-OES analysis showed that Mo dissolution follows a volcano trend with MXene loading (peaking at 5 wt %) before decreasing at 10 wt %. Overall, these results hold great promises for rational design strategies for MXene-supported water oxidation catalysts in alkaline electrolytes.