Surface modification in mixture of ZnO + 3%C nanocrystals stimulated by mechanical processing

Abstract

The photoluminescence (PL), Raman scattering and SEM images for the mixture of ZnO + 3% C nanocrystals (NCs) have been studied before and after of intensive mechanical processing (MP) with the aim to identify the nature of defects. The study reflects the diversity of physical processes occurring at MP: amorphizating the surface of ZnO NCs, crushing the individual ZnO NCs and carbon nanoparticles, covering the ZnO NC surface by the graphene layers, the oxidation partially of the graphene layers, carbon and ZnO NCs etc. Three stages of MP have been revealed which are accompanied by PL spectrum transformations: i) amorphizating the ZnO NC surface together with the generation of nonradiative recombination centers, ii) passivating the ZnO NC surface by the graphene layer with its oxidation partially and iii) further crushing of ZnO NCs, the oxidation of ZnO NCs and the formation of graphene (graphite) oxides. The new PL band peaked at 2.88 eV has been detected after 9 min of MP. Note that the passivation of the ZnO NC surface by graphene layer can be interesting for future technological applications.