Environment-friendly Preparation Of Graphene And Its Conception Design

Graphene is a material with the two-dimensional honeycomb lattice structure which was made of a single layer of sp2 hybridized carbon atoms. Because of its high electron mobility, excellent thermal stability and good flexibility, it displays a broad application prospects in the fields of chemistry, physics, materials, electronics and others. A growing number of researches are dedicated to the preparation and properties development of graphene. Reducing agent used mostly in conventional chemical redox of toxicity and high cost of follow-up treatment. Therefore, the search for a new green reductant to get graphene is currently a serious problem.In this research, the graphite oxide was prepared by improving the conventional Hammers method and the effects of pre-oxidation, reaction time under low temperature, the amount of oxidant, the addition of water and other process factors that affects the structure and degree of oxidation of products.The experimental results were quantified and characterized successfully by mean of resistance measurement with XRD characterization and the effects of various factors in the preparation process of graphite oxide were discussed. The results showed that the pre-oxidation process was a sulfuric acid intercalated process and graphite was not oxidized. Within a certain range, the reaction time was long under low temperature, the higher degree of oxidation of graphite oxide was prepared by using more oxidant. Also the addition of water had no effect on the degree of oxidation when 1he reaction temperature below 100℃. The optimal process conditions for preparation of graphite oxide with higher oxidation degree were obtained as follow:pre-oxidation reaction for 3 hours under low temperature, the ratio of oxidant to graphite equal 3.5, continuous addition of water under high temperature stage and controlled temperature within 100℃.For screening of several green reductants, vitamin C was used for the reduction of graphene oxide and the mechanism of reducing graphene oxide was researched. The studied results showed that the color was changed significantly during the reduction process from graphene oxide to graphene. Raman characterization showed that the D/G (ratio of D peak intensity to G peak intensity in Raman spectroscopy) of graphene was reduced significantly higher than that of graphene oxide, which clearly indicated that the parts of graphene oxide sp3 hybridized carbon atoms are reduced into sp2 hybridized carbon atoms. Infrared spectroscopy also showed that after the reduction, the absorption of graphene oxygen containing groups was significantly small, which can also prove that graphene oxide reduced.We concluded that, preparation of high quality graphene is the key for the development of research and application, so the optimum benefit of the above research is to prepare high quality graphene and providing valuable information for conceptual design, scale-up and industrialization of graphene production process.