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

Abstract

Semiconductor photocatalysis has attracted the attention of a wide audience for its outstanding capabilities in water purification and energy conversion. Herein, a noble-metal-free nanoheterojunction is created by planting zero-dimensional (0D) CdS nanograins, of 10–20 nm in size, on the surface of 2D SnS2 nanosheets (NSs) using an in situ chemical bathing deposition process, where SnS2 NSs have an average diameter of 400 nm and thicknesses of less than 20 nm. The possible formation mechanism of the CdS/SnS2 (CS/SS) heterogeneous nanostructure is elaborated upon. 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 the 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. The optimized CS/SS-3 sample consistently achieves the highest photocatalytic hydrogen production rate, at 10.3 and 5.7 folds higher than that of solo SnS2 and CdS panels, respectively. The boosted photocatalytic capacities of CdS/SnS2 heterostructures are essentially attributed to the formation of the closely interfacial incorporation of CdS and SnS2 semiconductors, resulting in the effective charge transportation and spatial separation of 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.