Structural, optical and antibacterial investigation of La, Cu dual doped ZnO nanoparticles prepared by co-precipitation method

Abstract

La, Cu dual doped ZnO with Cu = 0%-4% were prepared by co-precipitation route. The XRD pattern optimized the Cu content as 2% which restrict the secondary phase formation. The new phase at 38.7° corresponding to CuO (111) and the another phase at 42.3° related to Zn (101) came from un-reacted Zn2+ ions appeared in Cu = 4% doped sample. Zeta potential measurements confirms the stability of the particles. The blue shift of absorption edge and the energy gap from 3.66 eV to 3.99 eV by Cu doping was discussed by the shape of the particles, the distortion of the host lattice and generation of defect concentrations. The characteristic IR peaks around 470-489 cm-1 was related to the octahedral sites of Zn-O for Cu = 0 and 2% which is shifted to 616 cm-1 corresponding to the tetrahedral site at Cu = 4%. The shift in frequency was originated from the dissimilarity in the volume and bond lengths by the substitution of La and Cu in Zn-O. Based on the antibacterial report, it can be concluded that the Cu-doped Zn-La-O solid solution compose an effectual antimicrobial agent against pathogenic microorganisms. Cu = 4% doped sample possessed highest bacterial killing capacity because of the enhanced crystallite size and high density of oxygen vacancies which led the higher ROS values. Tuning of crystallite size and energy gap and the enhanced bactericial killing capacity by Cu addition is useful for opto-electronic device and medical applications.