Photocatalytic degradation studies of carbon and sulfur-doped K2Ta2O6

Non-metal doping is a promising approach to enhance the visible light absorption of wide bandgap materials. Visible light active C and S-doped K2Ta2O6 photocatalysts were prepared by the hydrothermal method and studied. The as-prepared catalysts were well characterized by PXRD, UV-Vis DRS, FESEM-EDS-elemental mapping, carbon-sulphur analysis, TEM-SAED, XPS and BET surface area analysis. Parent K2Ta2O6 is UV-active material, while C and S-doped K2Ta2O6 exhibit visible light absorption. The photocatalytic activity of all samples was assessed by examining the photocatalytic degradation of methylene blue (MB), methyl orange (MO) dyes and a colourless pollutant 4-chlorophenol (4-CP) in the presence of visible light. The percentage of degradation of MB (MO, 4-CP) in the presence of KTO, C-KTO and S-KTO is 52 (41, 45), 84 (73, 76) and 65 (53, 56), respectively. All samples exhibit activity for MB, MO and 4-CP degradation and C-doped K2Ta2O6 showed enhanced photocatalytic performance compared to other catalysts. Scavenger studies were conducted to identify the active reactive species which degrade the MB dye molecules. Moreover, photogenerated charge carrier separation was compared for all catalysts using photoluminescence (PL) and electrochemical impedance spectroscopy (EIS) measurements. The chemical stability and reusability of the C-doped K2Ta2O6 were tested. Furthermore, a photocatalytic mechanism is proposed for the degradation of MB over C-doped K2Ta2O6.