Preparation And Photocatalytic Activity Of TiO₂ And Graphene/TiO₂ Catalysts

As a new kind of inorganic semiconductor materials, Titanium dioxide has a remarkable effect on the degradation of pollutants and the improvement of environment, which is also the focus of recent reasearch. It has three kinds of crystal structure. Brookite is a metastable phase and not easy synthesis, so the photocatalytic activity of it is quite controversial. Furthermore, there are a lot of different opinions on the photocatalytic property of mixed crystal. In addition, in the synthesis process of graphene/Ti O2 composites, it was mainly prepared by complexing graphene oxide with single titanium source and then reducing graphene oxide, while the improvement of photocatalytic activity is limited. In this paper, the research work is done about the above two aspects:1、The preparation and photocatalytic property of Ti O2 photocatalyst with different crystal structureUsing tetrabutyl titanate as titanium source, Na F and sodium dodecyl sulfate as the control agent, pure anatase Ti O2, pure brookite Ti O2 and the anatase/brookite Ti O2 were prepared by hydrothermal method in this paper. The Scanning electron microscopy(SEM) showed that the pure anatase Ti O2 was globular while the pure brookite Ti O2 and the anatase/brookite Ti O2 was clubbed. Rhodamine B was selected as the simulated substrate to evaluate the photocatalytic activity of the catalysts. The results showed that the order of the photocatalytic activity is: anatase/brookite Ti O2> pure brookite Ti O2> pure anatase Ti O2. The reason may be that one-dimensional rod structure is more conducive to transfer electrons and holes than globular structure, and in mixed crystal the conduction level of brookite is higher than that of anatase, which can promote the migration of electrons. In addition, the growth mechanism of Ti O2 nanorod had been analyzed.2、The preparation and photocatalytic property of graphene/Ti O2 photocatalystUsing graphene oxide as support and isopropyl titanate as precursor, Ti O2 seed was deposited on the graphene oxide. Then graphene/Ti O2 was prepared by the hydrothermal method, using ammonium fluoride titanate and boric acid as raw materials. As contrast, another catalyst was prepared by using the single precursor ammonium fluoride titanate. It showed that graphene oxide can be reduced to graphene through the hydrothermal procedure and the reduction degree of graphene oxide in the composite prepared with two titanium sources was higher than that of the composite prepared by only one titanium source. Moreover, Ti O2 of the two catalysts was spherical and adhered well to the graphene sheet. Then, methyl orange was selected as the simulated substrate to evaluate their photocatalytic activities. The results showed that graphene/Ti O2 prepared by two titanium source had higher photocatalytic activity, which was ascribed to that the adsorbtion capacity of the graphene with higher reduction degree to the methyl orange was increased and the graphene can more easily transfer and transport the photo-generated electrons.