Synthesis And Photocatalysis Properties Of ZnO Nanoarrays And Its Composite Materials By A Microwave-assisted Low Temperature Aqueous Route

Zinc Oxide, which is oxide semiconductor possessing excellent physical andchemical properties such as wide and direct band gap of3.37eV, large excitonbinding energy of60meV, is of chemistry stability, easy to fabricate, nontoxic andcheap, has broad prospects in application as photocatalysts. There are alsodisadvantages beyond good performance: difficult to recycle, low efficiency of lightutilization due to the wide band gap and poor quantum efficiency. Thus, aiming atenhanced photocatalytic performance, ZnO rod-like nanoarrays and Ag/ZnOcomposite are successfully synthesized through microwave-assisted low temperatureaqueous solution route which is simple and environmental-friendly. And thephotocatalytic performance is studied. The main conclusions are as follows:First, Zinc Oxide (ZnO) nanoarray (rod-like nanostructure) was successfullysynthesized on the FTO glass substrate through low-temperature aqueous solutionand microwave-assisted synthesis using zinc nitrate hexahydrate (Zn(NO3)2·6H2O)and hexamethylenetetramine (HMTA) as raw materials. Parameters in preparationprocess such as reaction temperature, reaction time and solution concentration on themorphology and microstructure of ZnO nanoarray were studied, and possible growthmechanism of ZnO was proposed. Results indicated that the growth speed alongc-axis of ZnO crystal decrease, which lead to bigger size (about1m) at the reactiontemperature of75°C; the structure of ZnO crystal is determined by reaction time;the ZnO nanorod with high density, same orientation and uniform diameter wasobtained when the mixed solution was0.05M.Second, based on the above experiment, the as-prepared products wereproceeded under240W microwave oven for10mins, and ZnO nanoarrays weresynthesized by microwave aqueous solution route. After heat treatment, ZnOnanoarray which is less than200nm in diameter was obtained; when the power risingto400W, the product shows abnormal morphology which seems to be transformedfrom hexagonal-prism structure. The diameter of ZnO nanoarrays fabricated throughmicrowave aqueous solution route was just in approximately100nm. Furthermore, the photocatalytic performance of the ZnO nanoarrays as-synthesized wasinvestigated by photodegradating MB dye under visiblelight irradiation (400nm)for3h. which were heat treated and synthesized by microwave. The results showedthat the photocatalytic performance of ZnO nanoarrays with microwave-assistedmethod enhanced18%.At last, Ag nanoparticles were deposited on the surface of ZnO nanorods bymicrowave aqueous solution method. The photocatalytic performance of compositeswas studied by degrading methylene blue under visible light (400nm). It turnedout that the photocatalytic activity of4wt.%Ag/ZnO nanocomposite has the bestphotocatalytic performance, which was resulted of the Surface Plasmon Resonance.