Synthesis of cysteine, cobalt and copper-doped TiO2 nanophotocatalysts with excellent visible-light-induced photocatalytic activity

Charge separation is a vital process in order to achieve high performance TiO2-based photocatalysts. In the current study, to enhance the charge separation and suppress the charge recombination, novel nanocomposites of metal (Co and Cu) and nonmetal (C, N, S) doped TiO2 nanophotocatalyst (labeled as Co@C,N,S-doped TiO2 and Cu@C,N,S-doped TiO2) were synthesized via photochemical deposition-assisted sol–gel technique. The crystalline structures and characteristic of the prepared catalysts were analyzed by XRD, SEM, TEM, EDAX, PL, and UV–vis DRS spectroscopies. The photocatalytic performance of the samples was tested through decomposition of methyl orange (MO) aqueous solutions under UV and visible light irradiation. It was found that photodeposition of metals onto TiO2 slowed charge recombination compared to pure TiO2 in addition to formation of higher concentration of OH radicals on the TiO2 photocatalyst surface during light irradiation compared to pure TiO2. Beyond the optimum content of 2 wt% Cu and Co, a decline in photocatalytic performance was observed which was ascribed to metal agglomeration and blockage of the photosensitive TiO2 surface.