Synthesis of activated charcoal supported Bi-doped TiO2 nanocomposite under solar light irradiation for enhanced photocatalytic activity

[Display omitted] •Particle size and band gap of TiO2 is decreased upon Bi doping.•Methylene blue is successfully degraded over Bi/TiO2 and AC-Bi/TiO2.•AC-Bi/TiO2 is more active photocatalyst than TiO2 and Bi/TiO2.•AC-Bi/TiO2 led to a maximum extension of the spectral wavelength.•AC-Bi/TiO2 with enhanced photocatalytic activity produced much more reactive OH. In this study, activated charcoal (AC) supported bismuth (Bi)-doped Titanium dioxide (TiO2) nanocomposite was synthesized by precipitation method. The photocatalytic activity of AC-Bi/TiO2 was investigated for the degradation of methylene blue (MB) in aqueous solution under solar light irradiation. The incorporation of Bi3+ into the TiO2 lattice shifts the absorbance of TiO2 to the visible region then the addition of high adsorption capacity activated charcoal to improve the efficiency of TiO2. AC-Bi/TiO2 is found to be more efficient than Bi/TiO2 and undoped TiO2 for the degradation of MB under solar light irradiation. Surface morphology and bulk composition of the composite was obtained using high resolution-scanning electron microscopy with energy dispersive X-ray analysis. The crystal structure evolution and elemental composition were analyzed by combining Fourier transform-Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The ultraviolet-visible (UV–vis) absorption spectra show that the absorption edge for the composite with Bi3+ has red shift as compared with that of undoped TiO2. UV–vis diffuse reflectance spectra demonstrated a decrease in the direct band gap of AC-Bi/TiO2. BET surface area, pore radius and pore volume of the materials were calculated by applying the BET equation to the sorption isotherms. The production of hydroxyl radicals (OH) on the surface of solar light irradiated materialswere detected by photoluminescence technique using coumarin as a probe molecule. The mechanism of photocatalytic effect of the AC-Bi/TiO2 was proposed for the degradation of MB under solar light irradiation.