Studies on plasmon-enhanced photocatalytic efficacy of thin Cu x O films for the degradation of imidacloprid.

Imidacloprid (IMI), a widely used pesticide, poses significant environmental and health risks due to its toxicity to humans and aquatic life. Understanding its degradation behaviour is essential for developing effective remediation strategies. This study investigates the plasmon-enhanced photocatalytic degradation of IMI using copper oxide thin films decorated with gold nanoparticles (Cu x O/Au). Under UV-visible light, the incorporation of plasmonic Au in the Cu x O configuration enhances the photocatalytic activity by 36.6% compared to the pristine Cu x O film, with an overall degradation of more than 71%, which is maintained even after three repeated uses. Photoluminescence analysis provided evidence of reduced electron-hole recombination after the incorporation of Au, which was further validated by electrochemical analysis. The localized surface plasmon resonance (LSPR) and interband transition effects in Au-NPs increase the overall light absorption and concentration of charge carriers in the system. LC-MS analysis showed a decrease in the molecular ion signal of IMI and the appearance of several lower-m/z transformation-related ions, supporting the photocatalytic transformation of IMI.