Morphology Dependent Photocatalytic Activity of CuO/CuO-TiO₂ Nanocatalyst for Degradation of Methyl Orange Under Sunlight.

CuO nanoparticles have been extensively used as a photocatalyst because of their superior activity, selectivity and stability properties. The catalytic efficiency of these oxide nanoparticles can be improved by varying the size and shape of nanoparticles. Here, we report the synthesis of different shaped CuO nanoparticles and their impregnation on TiO₂. Optical analysis revealed that a considerable red shift (420 nm to 550 nm) in absorption spectra of CuO-TiO₂ nanocomposites was observed compared to bare CuO nanoparticles. DLS measurements showed that the average hydrodynamic size of CuO nanostars was increased from 160 nm to 584 nm after deposition on TiO₂. These nanocomposites were examined for photocatalytic degradation of methyl orange under sunlight radiation. It was observed that CuO-TiO₂ nanostars exhibited superior photocatalytic efficiency compared to CuO-nanoneedles, nanocrumbles and bare CuO nanoparticles. The CuO nanoparticles act as co-catalyst on the surface of TiO₂ and alter the physicochemical properties of TiO₂. The higher activity arises due to the fact that the doping of CuO reduces the recombination of charge carries (e--h+) and creates the intra-gap states which result in higher absorption of light radiations. Therefore, CuO nanoparticles impregnated on TiO₂ found to be an effective and ideal catalyst for the photodegradation of methyl orange dye.