Oxygen Vacancy-Induced Band Engineering and Metal Unsaturation in MoS2-MoO3 with Spillover-Based Confined Catalysis

The chemical reduction and hydrogen evolution reaction (HER) hold promise in sustainable energy generation and reducing global warming emissions. We have employed oxygen vacancy-induced band restructuring and multiple active sites in MoS2-MoO3, showing para-nitrophenol (PNP) and ferricyanide reduction and HER activity. The oxygen vacancy lowers the work function, band gap, and d-band center, stabilizing the antibonding state of MoS2-MoO3 and accelerating the H2 production with PNP reduction having a high turnover frequency (1.02 mmol g-1 min-1). However, the Mo5+/6+ site is a bifunctional center for the alkaline HER and PNP reduction, analyzed with X-ray photoelectron spectroscopy (XPS) and SCN- insertion during catalysis. For the acidic HER, the exothermically adsorbed H* on the O2- site (MoO3) undergoes favorable H* spillover to S2- (MoS2) in a confined space due to the low thermodynamic barrier (0.41 eV) and enhances the active surface area and mass activity with an overpotential of 114 mV at 10 mA cm-2. This work demonstrates the vacancy-induced band alignment of highly efficient MoS2- based multifunctional catalysis.

Automated summary

This study demonstrates the highly efficient catalysis of MoS2-MoO3 based on vacancy-induced band alignment. The oxygen vacancy reduces the work function, band gap, and d-band center of MoS2-MoO3, stabilizing the antibonding state and accelerating the hydrogen evolution reaction with para-nitrophenol reduction. The Mo5+/6+ site acts as a bifunctional center for alkaline hydrogen evolution and para-nitrophenol reduction, while the acidic hydrogen evolution reaction occurs through spillover of exothermically adsorbed H* from MoO3 to MoS2.