Photosensitive Ag-contained CeO2-ZnO сomposites with non-stoichiometric matrix: aspects of formation

Abstract

It was shown the forming of Ag-contained ZnO-CeO2 composites occurs due to the complex decomposition and structure transformation of oxide materials and Ag-complexes. It allows us to realise one synthesised approach for obtaining photosensitive materials with different particle sizes, defects and kinds of architecture. The possible mechanisms of photosensitivity of these materials are determined. For composite nanoparticles (NP) with sizes up to 30nm, the photosensitivity is connected with an abnormal decrease of bandgap energies at reducing NP sizes and an effective charge separation due to electron stocks on [Се3+…O2] centres and surface [Ce4+…O2-] oxidative centres formation. The appearance of the hyperfine structure pattern of six lines centred at g =2.002 and split by 93–94G in the ESR spectra of the composite structure confirms the realization of this mechanism. For more big NP sizes of this composite, the surface plasmon resonance plays a more significant role in the material's photosensitive properties. The position of surface plasmon resonance depends on the kind of realised structure. The phase composition, temperature and reduction determine the type of structure (NPs/AgNPs ore core/Ag shell) that will be recognised in the Ag-contained CeO2-ZnO system.