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.