Visible light sensitive Cu doped ZnO: Facile synthesis, characterization and high photocatalytic response

Abstract

The different concentrations of 0.0, 1.0, 2.5 and 5.0 wt% Cu-doped ZnO (Cu@ZnO) nanoparticles (NPs) have been synthesized for opto-photocatalytic applications by a facile and cost-effective route. The formation and structural analyses of Cu@ZnO NPs was recognized by X-ray diffraction (XRD), Fourier transform (FT)-Raman and Transmission electron microscopy (TEM). The average crystallite size of 28.9, 27.4 and 26.4 nm was calculated for (101) intense peak and found to be decreased with increasing the contents of Cu. The residual microstrain values are noted ~3.84 × 10−3, 4.03 × 10−3 and 4.19 × 10−3. The particle size of 170, 109, 127 and 175 nm is obtained for undoped and Cu doped ZnO NPs from FESEM. The optical band gap of Cu@ ZnO NPs were estimated through Kubelka-Munk theory and noted ~3.225, 3.150, 3.100 and 2.995 eV for 0.0, 1.0, 2.5 and 5.0 wt% Cu@ZnO NPs; this shows decreases with increasing the Cu contests in ZnO lattice. Photoluminescence (PL) spectra of Cu@ZnO NPs shows near band edge emission at 407–411 nm with emission band 565-572 nm correspond to intrinsic defects in ZnO lattice. The photocatalytic performance of Cu@ZnO NPs was assessed through decolourizing of methyl green beneath the visible light illumination (λ = 425–460 nm). Photocatalytic action of Cu@ZnO samples was 3.5 times greater to neat ZnO. Photocatalytic properties of Cu@ZnO NPs can be used for water purification in environmental applications.