Partially amorphized MnMoO4 for highly efficient energy storage and the hydrogen evolution reaction

Engineering the crystallinity of materials has been proved to be an efficient strategy to improve the material's properties in many applications. Herein, we demonstrate the successful transformation of electrochemically inert MnMoO4 into highly active bifunctional electrode materials for supercapacitors and as catalysts for the hydrogen evolution reaction through hydrogenation (hydrogen reduction at elevated temperatures). The hydrogenated MnMoO4 is partially amorphized with a one-fold increase in the electrochemically active surface area (ECSA). A 17-fold increase in specific capacitance is achieved, and the onset overpotential to drive the hydrogen evolution reaction markedly decreased to 105 mV from 194 mV. The highly enhanced electrochemical properties are likely due to the amorphous components and highly enhanced ECSA, which expose more active sites and enhance the charge-transfer kinetics on the surface.