The Preparation And Study Of Photocatalytic Activity Of The Composite Materials Of ZnO And Graphene

Photocatalysts,which has broad prospects, can act as an green environmental protectionagent in the treatment of organic wastewater. At present, TiO₂and its composites are used wi-dely acting as a photocatalyst. But, preparation process are complex, difficult to recycle and e-xpensive. ZnO which has lower cost and similar clearances with TiO₂is more effiency thanTiO₂in photocatalytic degradation of the dyes in aqueous solution. Thus ZnO is a better choi-ce in the aspect of photocatalysis. Graphene has a unique structure which makes it can be con-tacted with the compounds of benzene ring by π-π conjugated, and has a huge surface area sothat the organic pollutants can be adsorped by it. Combining the characteristics of ZnO and g-raphene, a low-cost, recyclable and efficient photocatalyst is prepared in a simple way. It is si-gnificancant in the aspects of the photocatalytic degradation of organic wastewater. The meth-od of modification of Hummers is used to prepare graphite oxide, and graphene oxide is obta-ined by ultrasonic divestiture. Then it is reduced to graphene by ethylenediamine reduction m-ethod. Using the unique properties of graphene, the surface of graphene with negative chargewhich acts as a base is fully contacted with the solution of zinc ion. Zn2+can be equably dep-osited on the surface of graphene by electrostatic adsorption. It becomes pioneer fluid of rGO--Zn（OH）2in alkaline solution, then the nanocomposite of rGO-ZnO is obtained by calcing. Itis characterized by atomic force microscope（AFM）, transmission electron microscopy（TEM）,scanning electron microscopy（SEM）, energy-dispersive x-ray spectroscopy（EDS）, fourier tra-nsform infrared spectroscopy（FTIR） and x-ray diffraction（XRD）. ZnO had been successfullymodified on the surface of graphene. Under the exposure of30W UV light, methyl orange isdegradated by the prepared nano-ZnO and rGO-ZnO respectively which act as photocatalyst.After55min, pure ZnO on the rate of degradation of methyl orange is71%, while the degrad-ation rate of rGO-ZnO is about100%. However, three times cycle experiments are carried, a-nd the results show that it is of good reproducibility, high stability, and can be recycled. Themechanism of photocatalytic degradation of methyl orange of rGO-ZnO is preliminary studie-d. Different from the traditional catalysts, rGO-ZnO has a dual function, which not only hashigh catalytic effect, but also adsorption.