Non-noble metal Ni/NiO heterojunction-modified ZnIn2S4 for simultaneous solar hydrogen production and degradation of 2,4-dichlorophenol: An oxygen vacancy engineering strategy

The photocatalytic conversion of pollutants into high-value-added chemicals driven by solar energy holds great potential for environmental protection and alleviating global energy shortages. In this study, an auxiliary calcination method was employed to modulate the band structure and oxygen vacancy concentration of Ni/NiO heterojunctions, thereby optimizing interfacial charge transfer. By constructing a composite catalyst comprising of oxygen-vacancy-enriched Ni/NiO heterojunctions and ZnIn 2 S 4 , the degradation of 2,4-dichlorophenol was coupled with the hydrogen evolution reaction. Experimental results demonstrated that under visible light irradiation, the optimized ZnIn 2 S 4 /Ni/NiO catalyst achieved a hydrogen evolution rate of 837.8 μmol·g −1 ·h −1 and 64.5 μmol·g −1 ·h −1 degradation rate for 2,4-dichlorophenol, representing 10.8-fold (77.6 μmol·g −1 ·h −1 ) and 6.2-fold (10.4 μmol·g −1 ·h −1 ) enhancements compared to pristine ZnIn 2 S 4 , respectively. This work systematically characterized and elucidated the interfacial charge transfer pathways and the role of oxygen vacancies in catalytic processes, providing new strategies for developing efficient and tunable non-noble metal bifunctional photocatalytic systems. • Oxygen-vacancy-enriched Ni/NiO co-catalysts synthesized via auxiliary calcination optimize interfacial charge transfer and band structure. • The adjustable Ni/NiO oxygen vacancies concentration and heterostructure enhance the scalability of the material. • ZnIn 2 S 4 /Ni/NiO could effectively separate photo-induced carriers and simultaneously achieve H 2 evolution and pollutants degradation. • Uncover the degradation mechanism and pathways of 2,4-DCP on ZnIn 2 S 4 /Ni/NiO.