Oxygen Vacancy-Induced Band Engineering and Metal Unsaturation in MoS<sub>2</sub>–MoO<sub>3</sub> with Spillover-Based Confined Catalysis
Dipayan Roy, Bikram Kumar Das, Saira Riaz, Dimitra Das, Sourav Sarkar, Kalyan Kumar Chattopadhyay
Abstract
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.