Photocatalytic activity in nanostructured zinc oxide thin films doped with metallic copper

Abstract

Nanostructured zinc oxide (ZnO) thin films doped with metallic copper were synthesized by a sputtering process. As the copper sputtering power increased from 20 to 40 W, the copper content increased from 2.37% to 14.15%. The film thickness increased from 166 nm (ZnO) to 387 nm (14.15Cu–ZnO). The crystallite size on plane (002) of ZnO films was 7.95 nm and increased to 17.82 nm at 14.15 Cu–ZnO films. Spherical particles were observed, and the surface roughness increased from 2.77 nm (ZnO) to 5.35 nm (14.15 Cu–ZnO). The intercalation of metallic copper in the ZnO lattice decreased the optical transmittance and photoluminescence (PL) intensities and shifted the absorption edge towards higher photon wavelengths. Methyl green dye (MG) was used as a pollutant in wastewater to examine the photocatalytic activity of the films. The degradation ratio of MG dye in ZnO thin films was 60%, reaching 99.8% at 14.15 Cu–ZnO thin films.