Constructing noble-metal-free 0D/2D CdS/SnS2 heterojunction for efficient visible-light-driven photocatalytic pollutant degradation and hydrogen generation.

Semiconductor photocatalysis has attracted a wide attention for its outstanding capacity on water purification and energy conversion. Herein, a noble-metal-free nanoheterojunction by planting zero-dimensional (0D) CdS nanograins with 10-20 nm in size on the surface of 2D SnS2 nanosheets (NSs) has been created using an in-situ chemical bathing deposition process, where SnS2 NSs have the average diameters of 400 nm as well as thicknesses of less than 20 nm. The possible formation mechanism of CdS/SnS2 (CS/SS) heterogeneous nanostructure is elaborated. The catalytic activities over CS/SS nanocomposites for the photodegradation of organic dye and hydrogen evolution from photolysis water splitting are examined under visible light irradiation. The apparent rate constant (k) of the optimal CS/SS-3 composite in decontamination of methylene blue (MB) is up to 3.34 and 1.87 times as high as that of pristine SnS2 and pure CdS counterparts, respectively. Consistently, the optimized CS/SS-3 sample achieves the highest photocatalytic hydrogen production rate, being 10.3 and 5.7 folds higher than that of solo SnS2 and CdS panels, respectively. The boosted photocatalytic capacities of CdS/SnS2 heterostructures is essentially attributed to the formation of the closely interfacial incorporation between CdS and SnS2 semiconductors, resulting in the effective charge transportation and spatial separation for the photoinduced electron-hole pairs. Furthermore, the traditional type-II charge transfer pathway is proposed based on the perfect band structure and the free radical experiment results.