Photocatalytic hydrogen production performance of ZnCdS-encapsulated bimetallic NiMoO4 rod-like heterojunctions in the reforming of lignin model compounds

Abstract

Biomass photoreforming for hydrogen production is a promising approach that utilizes solar energy to facilitate the reaction between biomass and water, achieving efficient conversion of both solar and biomass energy into hydrogen. In this study, ZnCdS (ZCS) nanoparticles were loaded onto NiMoO₄ (NMO) nanorods via calcination and hydrothermal methods to construct ZCS/NMO S-scheme heterojunctions. The resultant composites were systematically characterized for physicochemical properties. Among the prepared catalysts, ZCS/NMO-10 % demonstrated the highest hydrogen evolution activity, with hydrogen production rates of 600.27 μmol·g⁻¹·h⁻¹ and 165.54 μmol·g⁻¹·h⁻¹ using a lignin model compound and sodium lignosulfonate as substrates, respectively. The introduction of the bimetallic oxide effectively accelerated the hydrogen evolution reaction. This improved photocatalytic performance is ascribed to the formation of the heterojunction, which not only enhances charge separation but also preserves strong redox capabilities. Additionally, liquid phase analysis of the lignin model compound (PP-ol) solution after catalysis revealed that PP-ol was oxidized into three high-value chemicals during the oxidation half-reaction, with a maximum conversion rate of up to 89.10 %. A possible catalytic reaction mechanism is also proposed. Overall, this work provides a promising strategy for mitigating energy shortages and environmental pollution.