rGO and g-C₃N₄ as synergistic additives in SnS₂-MoS₂ hybrid nanocomposites for photocatalytic and electrochemical applications: a detailed study

Energy storage and water remediation are two quite important issues of the current world. Developing novel multi-component composites with active carbon materials opens up new avenues for research. In present work, SnS₂-MoS₂ and their rGO-gC₃N₄ nanocomposites (rGO-SnS₂-MoS₂, gC₃N₄-SnS₂-MoS₂, rGO-gC₃N₄-SnS₂-MoS₂) were synthesized via hydrothermal and ultrasonication methods, respectively. The crystal structure, morphological analysis and optical properties were confirmed by means of X- ray diffraction (XRD), Raman, Field – Emission Scanning Electron Microscopy (FESEM) and Ultra Violet (UV)- Visible spectroscopic techniques. Photocatalytic activity of SnS₂-MoS₂ and their nanocomposites were tested by photodegradation of Methylene blue (MB) and Rhodamine B (RhB) in the presence of visible light. Photocatalytic degradation efficiency of SnS₂-MoS₂ is 97% in 40 min for MB dye and for rGO- SnS₂-MoS₂ is 96% in 35 min for RhB dye. rGO-SnS₂-MoS₂ has shown higher specific capacitance of 215 F/g at current density of 30 mA/cm² as compared to other electrodes. Maximum power density of 900 W/kg for rGO- gC₃N₄-SnS₂-MoS₂ and maximum energy density of 7.5 Wh / kg for rGO-SnS₂-MoS₂ are observed at different combinations of current / area. An acceptable and better performance is observed for rGO - SnS₂ - MoS₂ with energy density of 5.6 Wh/kg at 455 W / kg power density. Notably, the rGO-SnS₂-MoS₂ can be employed as efficient photocatalyst and active electrode for supercapacitor applications.