Electrochemically fabricated MoO3–MoO2@NiMo heterostructure catalyst with Pt-like activity for the pH-universal hydrogen evolution reaction

Currently, efficient hydrogen production via water electrolysis is hindered by the insufficient performance, high cost, and complex fabrication procedure of the hydrogen evolution reaction (HER) electrode. Herein, a facile fabrication method consisting of electrodeposition and a subsequent electrochemical etching process is proposed for high-performance Mo oxide-decorated NiMo (MoO3–MoO2@NiMo) heterostructure catalysts supported by carbon paper. By controlling the conditions used in electrodeposition, the composition and morphology of NiMo deposits could be manipulated. The parameters in the following etching process could be further adjusted to tune the MoO3–MoO2@NiMo heterostructure catalysts, with a significant effect on the intrinsic HER activity. Owing to the synergetic effect of the interface with a roughened morphology, the optimized catalyst exhibited Pt-like activity in the universal pH range. In particular, the HER overpotentials at −10 mA cm−2 are 27.9, 82.6, and 33.4 mV in 0.5 M H2SO4, 1.0 M PBS, and 1.0 M NaOH electrolytes, respectively, which mostly exceed the results for state-of-the-art catalysts. The present strategy for preparing high-performance MoO3–MoO2@NiMo heterostructure electrodes at room temperature and ambient pressure could be expanded to explore elemental synergy in other metal oxide@metal heterostructure electrodes.