Direct Sunlight driven photocatalytic degradation of hazardous organic dyes using TiO2-NiO nanocomposite p-n junction

TiO2 is stable and nontoxic, an effective, low cost, semiconductor photo catalyst to degrade most of the organic pollutants. Nevertheless, the practical application of TiO2 are limited due to two important reasons, while one of the reasons is rapid recombination of electron and hole pair and other one is larger band gap 3.2ev, which permits to absorb 3-4% of solar energy. To enhance photocatalytic activity, several TiO2-metal oxide composites have been used. Due to their electron hole separation ability p-n junction, type semiconductor has become more focused in the last few years. TiO2-NiO nanocomposite is one such catalyst; the presence of NiO facilitates the separation of the hole and the electron pair and encourages the interfacial charge transfer; which facilitates TiO2-NiO a good photocatalyst under direct sunlight. The objective of the study is to synthesise nanocomposite of different mole ratios of NiO and TiO2, to investigate the physicochemical properties such as XRD for phase and purity test, SEM –EDX for morphology and percentage elemental composition, UVDRS for band gap analysis. Photocatalytic activity of TiO2-NiO p-n junction nano structures experiments were carried out under direct sunlight in different systems; using aqueous solution of the dye with effect of pH, concentration of dye, catalyst loading and time on degradation of the organic dye were studied. With increasing the concentration of NiO in to TiO2-NiO composite increases the photocatalytic activity due to narrowing of the band gap attributed to interfacial charge transfer or higher hole mobility.