Modification of optical properties in ZnO particles by surface deposition and anchoring of NiO nanoparticles

Nanodispersion of NiO nanoparticles on the surface of ZnO microparticles has been carried out by means of a low energy dry mixing method. This method keeps the shape and size of the ZnO microparticles that served as support to hold the NiO nanoparticles. The dispersion and anchoring of the NiO nanoparticles takes place by means of an electrochemical reaction with the OH-groups present at the ZnO surface. The process took place at room temperature and cation interdiffusion between ZnO and NiO have not been detected by structural analysis. Nevertheless, changes in the optical properties of semiconductor ZnO particles have been observed due to the deposition of the nanoparticles. These changes correlate with the amount of NiO nanoparticles at the ZnO particle surface. The amount of defects, i.e. oxygen vacancies, interstitial oxygen and zinc vacancies, rises with the increasing NiO content.

Research highlights▶ We show a method to disperse NiO nanoparticles on ZnO surface without modifying the materials. ▶ Though no secondary phases appear, changes on Raman and luminescence spectra are seen. ▶ Raman changes are due to stress relief at ZnO surface by the interaction with NiO. ▶ Nanoparticles deposition increases ZnO visible emissions, related to material defects. ▶ Semiconductor emission properties can be modified depositing nanoparticles over them.