Construction of mesoporous carbon nitride/binary metal sulfide heterojunction photocatalysts for enhanced degradation of pollution under visible light

A novel binary metal sulfide fabricated with mesoporous carbon nitride (mpg-C3N4/SnCoS4) was synthesized by the simple in situ hydrothermal method. Characterizations indicate that a homogenous dispersion of SnCoS4 nanoparticles on the ordered mesoporous structure of mpg-C3N4 (248 m2 g−1) with average diameter of 25 nm, providing more catalytic active sites and large contact regions for adsorption and degradation of pollutant. By taking advantage of this feature, the photocatalytic properties are evaluated systematically by degradation of rhodamine B (RhB) and methylene blue (MB) under visible light irradiation, and the photocatalyitc performance of MCN/SnCoS4-50 is much higher than that of pristine SnCoS4, mpg-C3N4, MCN/CoS2 and MCN/SnS2. Moreover, mpg-C3N4/SnCoS4 heterojunction exhibits excellent photostability after four recycles. The enhanced photo-induced oxidation and reduction activity of mpg-C3N4/SnCoS4 can be attributed to not only the high surface area of composite, but also the formation of n-n type heterojunction. The incorporation of binary metal sulfides into mpg-C3N4 can decrease the band gap, alter the CB and VB potential, enhance the photoinduced interfacial charge transfer, and therefore increase the charge separation efficiency during the photocatalytic reaction.