A facile in situ solvothermal method for two-dimensional layered g-C3N4/SnS2 p-n heterojunction composites with efficient visible-light photocatalytic activity

To overcome the fast recombination rate of electron-hole pairs of individual SnS2, p-n heterojunction g-C3N4/SnS2 composites were fabricated as high-efficiency visible-light photocatalyst to photodegradate the organic dye MB. The morphologies, structures, compositions, and photocatalytic properties were characterized. The SnS2 shows two-dimensional layer structure with an average thickness of 20 nm and diameter size of about 2 μm, and the g-C3N4 nanoflakes were uniformly deposited on the surface of SnS2 nanosheets. In comparison with the bare g-C3N4 and SnS2, the composites show improved photocatalytic activity under visible light, which is sensitive to the content of g-C3N4. In particular, the 15% g-C3N4/SnS2 composites exhibit the highest photocatalytic activity and outstanding reusability, which can degrade 88.01% MB after only 1 h in the visible light (λ > 420 nm) range. The g-C3N4/SnS2 heterojunction composites show outstanding reusability after four times cycling experiments. The improved photocatalytic activities of composites are attributed to abundant active species, increased charge separation, and decreased electron-hole pair recombination, which originated from the large specific surface area and efficient interfacial transport of photo-induced charge carriers between SnS2 and g-C3N4. These results suggest that the two-dimensional layered g-C3N4/SnS2 p-n heterojunction composites are promised to be a high-efficiency visible-light photocatalyst.