Graphene-like h-BN supported polyhedral NiS2/NiS nanocrystals with excellent photocatalytic performance for removing rhodamine B and Cr(VI)

Human health is deteriorating due to the effluent containing heavy metal ions and organic dyes. Hence, photoreduction of Cr(VI) to Cr(III) and degradation of rhodamine B (RhB) using a novel photocatalyst is particularly important. In this work, h-BN/NiS₂/NiS composites were prepared via a simple solvothermal method and a double Z-scheme heterojunction was constructed for efficiently removing RhB and Cr(VI). The 7 wt-% h-BN/NiS₂/NiS composites were characterized via a larger specific surface area (15.12 m²·g^–1), stronger light absorption capacity, excellent chemical stability, and high yield of electrons and holes. The experimental result indicated that the photoreduction efficiency of the 7 wt-% h-BN/NiS₂/NiS photocatalyst achieved 98.5% for Cr(VI) after 120 min, which was about 3 times higher than that of NiS₂/NiS (34%). However, the removal rate of RhB by the 7 wt-% h-BN/NiS₂/NiS photocatalyst reached 80%. This is due to the double Z-scheme heterojunction formed between NiS₂/NiS and h-BN, which improved the charge separation efficiency and transmission efficiency. Besides, the influence of diverse photogenerated electron and hole scavengers upon the photoreduction of Cr(VI) was studied, the results indicated that graphene-like h-BN promoted transportation of photoinduced charges on the surface of the h-BN/NiS₂/NiS photocatalyst via the interfacial effects.