A Comparative Study of Photocatalytic Activity of Some Coloured Semiconducting Oxides

The use of colored semiconductor oxide like copper (II) oxide and nickel (II) oxide for photocatalytic bleaching of rose bengal was investigated in detail. In order to harness the solar energy, the effective wavelength of the photocatalyst is to be expanded into the visible region and that increases the rate of photocatalytic bleaching of the dye. Progress of the reaction was observed spectrophotometrically. The comparative studies of photocatalytic activity of copper (II) oxide (CuO) and nickel (II) oxide (NiO) was made using photocatalytic bleaching of rose bengal as modal system. The effect of various parameters like concentration of dye, pH, amount of semiconductor, light intensity etc. on the rate of photocatalytic bleaching of the dye was also observed. On the basis of rate of the reaction (rate constant) the order of photocatalytic activities of the semiconductor oxides was found to be CuO > NiO. A tentative mechanism for the photocatalytic bleaching of rose bengal has also been proposed.