Photocatalytic degradation of methylene blue under visible light using carbon-doped titanium dioxide as photocatalyst

A visible light-active photocatalyst, carbon-doped titanium dioxide (C-doped TiO2) with an anatase phase, was synthesized using a simple and cost-effective method, with glucose serving as the carbon source for doping. The surface morphology, crystal structure and elemental composition of the catalyst was analyzed by SEM, XRD and EDX respectively. Raman spectroscopic and XRD analysis showed the consistency of the anatase phase throughout the preparation process. FT-IR, TGA, and EDX depicted the purity of the prepared catalyst. SEM images revealed that the average particle size of the catalyst is approximately 178 nm, which is smaller than that of pure TiO2. Finally, as a proof-of-concept photocatalytic activity of the catalyst was investigated on a typical organic dye, methylene blue, under two different light sources (UV light and visible light) by varying the catalyst amount, the concentration of dye, and pH of the degrading medium. Results showed that the prepared C-doped TiO2 shows a promising result under the visible light irradiation which seems limited in case of pure TiO2. The optimum photocatalytic degradation conditions are pH 3, catalyst dosage 0.15 g, and dye concentration 3 × 10−5 M. At optimum conditions visible light shows 53 % degradation and UV light degrades almost all the dye molecules. The enhanced photocatalytic activity of C-doped TiO2 in visible light is due to carbon doping, which reduces the bandgap energy and enables the absorption of visible light photons. This convenient technique can be a great solution for the removal of dyeing wastes economically using low-cost visible light or sunlight and large scale production for industrial application. [Display omitted]