Oxidation-induced catalytic performance of heterostructured Ni-TiO2 nanoparticles and formation of Leuco-Methylene blue

摘要

Ni-TiO2 catalysts have been successfully developed by simple sol-gel techniques with variations in Ni2+ concentration. The reduced bandgap suggests the appearance of the intragap various localized defect states and oxygen vacancies. The formation of oxygen vacancies and its effect on photocatalysis with the presence of the colour centres (F, F+, F++) in the photocatalytic mechanism by replacement of anion vacancy and electron pair displacement are discussed. The low concentration (0.02 M) of Ni2+ doping represents a large amount of oxygen vacancy, which assures the high capability of visible light absorbance. The chemical reaction mechanism of oxidation/hydrogenation-induced photocatalytic behaviour through formation of Leuco-MB is also established. The design of anatase/rutile heterostructure and the proposed mechanism of Schottky induced charge transfer phenomenon under visible light irradiation are also embedded in our work. In comparison with many other early reports, our results show that the 0.02 M concentration of Ni2+ doping has an outstanding photocatalytic activity with complete decolouration with evolution of Leuco-methylene blue and thus obtained 100% total degradation of toxic MB compounds from the aqueous solution after just only 30 min of visible light illumination.