Boosted electron-transfer/separation of SnO2/CdSe/Bi2S3 heterostructure for excellent photocatalytic degradation of organic dye pollutants under visible light

Nowadays, the discharge of hazardous pollutants from industries into drinking water has become a significant issue worldwide. In the present work, SnO2/CdSe/Bi2S3 heterostructure photocatalyst along with pristine SnO2, CdSe, and Bi2S3 was synthesized via a facile hydrothermal route. The fabricated catalysts were characterized by different analytical techniques such as X-ray diffraction (XRD), Atomic force microscopy (AFM), Dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), UV-visible diffuse reflectance spectroscopy, and Electrochemical impedance spectroscopy (EIS) to study the structural, morphological, optical, and electrochemical properties, respectively. The XRD diffractograms confirmed the formation of nanocomposite having SnO2 (Tetragonal), CdSe (Cubic), and Bi2S3 (Orthorhombic) phases. The photocatalytic experiment results showed that the nanocomposite catalyst exhibited excellent photodegradation than individual catalysts. The nanocomposite catalyst degraded methylene blue (MB) dye entirely after 60 min in visible light illumination, considerably higher as compared to pristine SnO2 (53.8%), CdSe (78.5%), and Bi2S3 (86.3%). The nanocomposite catalyst also has the potential to degrade various pollutants such as rhodamine B (RhB), methyl orange (MO), safranin-O (SO), and methyl red (MR) dyes with efficiency 99.8, 91.7, 75.0, and 98.5 %, respectively, with superior reusability up to 5th cycles against MB dye. The narrow optical energy bandgap in the visible region (UV results), the more significant flow of charge carrier at the catalyst's surface (EIS results), and higher electrontransfer/separation achieved by the heterostructure formation responsible for the boosted photocatalytic activity of nanocomposite catalyst. Furthermore, the present finding introduced an efficient photocatalyst with improved charge carrier kinetics for water purification applications.

Automated summary

The discharge of hazardous pollutants from industries into drinking water is a significant global issue. In this study, a SnO2/CdSe/Bi2S3 nanocomposite photocatalyst was synthesized and characterized for its excellent photodegradation performance. The results showed that the nanocomposite catalyst exhibited efficient degradation of various organic dyes under visible light, and it had superior reusability. The improved photocatalytic activity of the catalyst was attributed to its narrow energy bandgap, high charge carrier mobility, and heterostructure formation. Therefore, this research is of great importance for water purification applications.