Novel Z-scheme Ag-C3N4/SnS2 plasmonic heterojunction photocatalyst for degradation of tetracycline and H2 production

A novel Z-scheme Ag-C3N4/SnS2 plasmonic heterojunction photocatalyst was developed for the first time by in situ forming 3D flower-like SnS2 microspheres on the 2D Ag-C3N4 nanosheet. The photocatalytic performances of the samples were systematically examined via the photocatalytic water splitting for H2 production and photocatalytic degradation of tetracycline (TC) under visible light irradiation. Among the as-prepared Ag-C3N4/SnS2 samples with various Ag content, 5Ag-C3N4/SnS2 (the mass ratio of Ag to g-C3N4 is 5 wt%) sample exhibited the most efficient photocatalytic performances. The apparent reaction rate constant of 5Ag-C3N4/SnS2 for the photocatalytic oxidation of TC was 0.0201 min−1, which was 7.2, 4.9 and 3.0 times higher than those of the bare SnS2 (0.0028 min−1), g-C3N4 (0.0041 min−1) and g-C3N4/SnS2 (0.0066 min−1), respectively. As for the H2 production, a maximum of 1104.5 μmol g−1.h−1 can be achieved for the 5Ag-C3N4/SnS2. The enhancing photocatalytic performance was attributed to the enhanced absorbance in the visible light region caused by localized surface plasmon resonance (LSPR) and the efficient interfacial charge migration and separation in Ag-C3N4/SnS2 samples. In addition, the photocatalytic degradation pathway of TC was proposed based on nine degradation products confirmed by GC–MS. Finally, there were a series of characterization, such as time-resolved fluorescence emission decay spectra, photoelectrochemical characterizations, and stimulation methods (DFT, CASTEP, and FDTD), to verify the Z-scheme plasmonic heterojunction photocatalysis mechanism.