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

Abstract

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.