Construction of Ni-doped SnO2-SnS2 heterojunctions with synergistic effect for enhanced photodegradation activity.

Construction of heterostructures with proper band alignment and effective transport and separation of photogenerated charges is highly expected for photocatalysis. In this work, Ni-doped SnO2-SnS2 heterostructures (NiSnSO) are simply prepared by thermal oxidation of Ni-doped hierarchical SnS2 microspheres in the air. When applied for the photodegradation of organic contaminants, these NiSnSO exhibit excellent catalytic performance and stability due to the following advantages: (1) Ni doping leads to the enhancement of light harvesting of SnS2 in the visible light regions; (2) the formed heterojunctions promote the transport and separation of photogenerated electrons from SnS2 to SnO2; (3) Ni-SnO2 quantum dots facilitate the enrichment of reactants, provide more reactive centers and accelerate product diffusion in the reactive centers; (4) the SnS2 hierarchical microspheres constituted by nanoplates provide abundant active sites, high structural void porosity and accessible inner surface to faciliate the catalytic reactions. As a result, the optimized NiSnSO can photodegrade 92.7% methyl orange within 80 min under the irradiation of simulated sunlight, greatly higher than those of pure SnS2 (29.8%) and Ni-doped SnS2 (52.1%). These results reveal that the combination of heteroatom doping and heterostructure fabrication is a very promising strategy to deliver nanomaterials for effectively photocatalytic applications.