Boosting photocatalytic simultaneous hydrogen evolution and plastic reforming via surface hydroxylation over a NiMoO4/CdS heterojunction: interfacial microenvironment and electronic structure regulation

Abstract

The interfacial interaction between catalysts and substrate molecules plays a pivotal role in enhancing photocatalytic hydrogen evolution efficiency. Rational surface design and modification of photocatalysts can effectively reduce the activation energy barriers, enabling sustainable and high-performance hydrogen production. In this work, hydroxyl (–OH) groups were engineered into NiMoO₄ using a straightforward solvothermal method, resulting in an optimized interfacial microenvironment that promoted favorable reaction kinetics for enhanced photocatalytic hydrogen evolution. The incorporated –OH groups form hydrogen bonds with H₂O molecules, creating a unique micro-environment that facilitates water molecule enrichment, activation, and dissociation. Notably, hydroxylation induced electronic structure modulation through charge redistribution, generating highly active Ni sites that lower the energy barrier for hydrogen reduction. The optimized hydroxylated NiMoO₄/CdS (HNCS) composite photocatalyst exhibited exceptional photocatalytic performance, achieving a hydrogen evolution rate of 89.37 mmol g⁻¹ h⁻¹ with an apparent quantum yield (AQY) of 69.0% at 475 nm. The results demonstrate that hydrogen is predominantly derived from water, with lactic acid (LA) undergoing selective oxidation to form the high-value platform chemical pyruvic acid (PA). Notably, the system proves applicable to the aqueous-phase reforming of polylactic acid (PLA), achieving simultaneous hydrogen production and conversion of plastic waste into useful chemical products. This work provides fundamental insights into the mechanistic role of surface functional groups in promoting photocatalytic hydrogen generation.