Improved photocatalytic performance of Z-scheme heterostructured SnS2/Sg-C3N4 composite: A new route to increasing specific surface area

In this study, SnS 2 /S-doped g-C 3 N 4 (Sg-C 3 N 4 ) composite with SnS 2 and Sg-C 3 N 4 in the weight ratio of 9:1 was prepared by a hydrothermal method . For comparison, composites of SnS 2 /Sg-C 3 N 4 with weight ratios of 9:0.05 and 9:1.5, pure SnS 2 , Sg-C 3 N 4 , and g-C 3 N 4 were also prepared using the same processing parameters. Microstructural characterization showed that nano-sized SnS 2 particles were deposited on Sg-C 3 N 4 to form a Z-scheme photocatalyst . The chemical valence of the doped S in Sg-C 3 N 4 was +6, allowing the surface of Sg-C 3 N 4 in the composite to be considerably uneven for the deposition of SnS 2 . The uneven surface of Sg-C 3 N 4 resulted in a rough surface of the SnS 2 /Sg-C 3 N 4 composite, which significantly enhanced the specific surface area and light absorption over a wide wavelength range of 200–1000 nm. The carrier transfer capability and lifetime of g-C 3 N 4 were improved after S doping. The lifetime and transfer ability of the photoproduced carriers in the composite were improved by the Z-scheme heterojunction . Consequently, the rate constant of the composite is thrice that of pure SnS 2 and 57 times that of Sg-C 3 N 4 . This work demonstrates a novel route to enhance light absorption over a wide wavelength range: depositing a semiconductor on a base semiconductor with an uneven surface charge distribution can produce a composite with a rough surface, i.e., a large specific surface area.