Controlled synthesis of CuO decorated defect enriched ZnO nanoflakes for improved sunlight -induced photocatalytic degradation of organic pollutants

We report synthesis and application of a unique heterojunction nanocomposite formed between copper nano- particles (CNPs) and defect rich ZnO nanoflakes for application towards water remediation. Systemic variation in CNPs functionalization was seen to modulate the optical, structural and photocatalytic properties of the het- erojunction, which were found to be well in accordance with the results from TEM, UV-DRS and EPR. The remediation ability of the heterojunction measured in terms of its photocatalytic ability was studied by de- grading three different organic dye pollutants Rhodamine 6G (R6G), Methylene Blue (MB) and Methyl Orange (MO) using solar light (850 W/cm(2)) as the renewable excitation source. CNPs loading density was seen to follow a direct linear relationship to optical absorbance and band gap narrowing. The initial increase in photolytic efficiency is associated with improved visible light response and reduced band gap due to attachment of CNPs while reduction in activity was found to be associated with generation of self-recombination centres in CuO functionalization. Optimized CNP modified ZnO nanoflakes was able to decompose 10 mu M of R6G, MB and MO dye solutions in 80, 40 and 60 min respectively.