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 MoS 2 –MoO 3, 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 MoS 2 –MoO 3 and accelerating the H 2 production with PNP reduction having a high turnover frequency (1.02 mmol g –1 min –1 ). However, the Mo 5+/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 O 2– site (MoO 3 ) undergoes favorable H* spillover to S 2– (MoS 2 ) 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 MoS 2 -based multifunctional catalysis.