Maintaining the localized surface plasmon resonance of copper nanoparticles by defective TiO2 thin films

The localized surface plasmon resonance (LSPR) of copper nanoparticles (CuNPs) damps quickly in air due to the easy oxidation of copper atoms. Finding ways to retard the oxidation of CuNPs is critical for the applications based on the LSPR of CuNPs. In this paper, we report on a new method to maintaining the LSPR of CuNPs by deposition of CuNPs on TiO2 thin films in vacuum followed by annealing in nitrogen ambient. The anti-oxidation properties of the CuNPs were improved greatly. In three days, the LSPR intensities at 532 and 633 nm were reduced by only 40 and 32%, respectively. This method is simple and cost-effective.