Novel Ag2S quantum dot modified 3D flower-like SnS2 composites for photocatalytic and photoelectrochemical applications

Novel 3D flower-like Ag2S/SnS2 composites were fabricated by a hydrothermal and ion exchange method. Uniform Ag2S quantum dots were homogeneously interspersed on 3D flower-like SnS2. The samples were characterized through X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) analysis. As expected, the as-prepared Ag2S quantum dot modified 3D flower-like SnS2 composites exhibited enhanced photoelectrochemical (PEC) performance and photocatalytic activities. The photocurrent density of 3% 3D flower-like Ag2S/SnS2 at 2.0 V (vs. Ag/AgCl) (0.65 mA cm−2) was about 3.25 times higher than that (0.2 mA cm−2) of 3D flower-like SnS2. The photocatalytic activity of 3D flower-like Ag2S/SnS2 composites was assessed through the degradation of methyl orange and the photocatalytic H2 evolution performance under visible light irradiation. The coupling of SnS2 and Ag2S quantum dots could notably promote the photocatalytic activity. The experimental results indicated that 3% 3D flower-like Ag2S/SnS2 composites showed the best photocatalytic performance for the degradation of methyl orange. These composites also exhibited a high H2 evolution rate of 574.7 μmol h−1 g−1 under visible light irradiation, approximately 5.57 times higher than that of pure 3D flower-like SnS2. Based on the calculation, radical trapping tests and ESR, a plausible mechanism for increased photoactivity was proposed. This work provides experimental insight into the design of low-cost photocatalysts for highly efficient photodegradation and photocatalytic H2-production.