The Fabrication Of Cu/ZnO Composite Nanomaterials By Photo-induced Reduction Method And Its Characterization

The composite nanomaterials of semiconductor ZnO and metal can fully display the excellent properties of each unit with important applications in catalysis, gas sensor and photoelectricity. In this dissertation, Cu/ZnO composite nanomaterials were prepared by photo-induced catalytic method on T-ZnO substrate. The key parameters of the reaction were figured out by the thermodynamics analysis and calculation. Five group experiments with two serials were devised to investigate the effect of light source, amount of copper ions and reaction time on the fabrication of Cu/ZnO composite nanomaterials.Experiment results showed that: with median pressure mercury light source and copper ions amount about 1mmol and 2mmol, the deposit copper nanoparticles on ZnO substrate increased as reaction was carried on under the same reaction conditions such as buffer reagent, hole remover (formaldehyde) and solution volume. The diameter of copper nanoparticles grew fromφ40nm at 10 minute to aboutφ60nm at 60 minute, and Cu/ZnO composite nanostructures were formed. After 50 minute, pure amorphous copper nanoparticles with diameter aboutφ80nm were obtained, which transformed to polycrystal structures by the radiation of electron beam in the chamber of TEM equipment. The diameter of copper particles reduced fromφ100nm toφ70nm as copper ions amount increased when reaction time was fixed at 30 minute. The high resolution TEM results proved the combination of copper particles and ZnO substrate was tight. With xenon light source, the deposit copper formed a thin layer firstly, and then formed particles on ZnO substrate aboutφ50nm. At 70 minute, the reacted product was Cu nanoparticles with diameter aboutφ80-90nm.The ZnO was prone to be photo-corroded by median pressure mercury light source with higher energy. No diffraction peaks of ZnO were measured at samples with mercury light source when reaction time was longer than 50minute. But diffraction peaks of ZnO can also be measured at samples with xenon light source even when reaction time was 70 minute. As photoluminescence (PL) test, compared with pure ZnO, the visible spectral range emission of layer Cu/ZnO composite nanomaterials was redshift from 385nm to 390nm, and ultraviolet range emission was blueshift from 610nm to 585nm. This phenomenon was related to the surface copper layer. The PL peaks of particle Cu/ZnO composite nanomaterials were quenched by the copper particles. No emission peaks were detected in pure copper nanoparticles.