Preparation Of Graphene-based Composite Materials And Research Of Their Application In Environment And Energy

Graphene has attracted a great deal of attention because of its excellent physical and chemical properties. In addition, it has been used as supports of nanoparticles due to its large specific surface area. Thus, its potential applications include catalyst, sensors, supercapacitors, batteries, and so on.In recent years, there are plenty of organic pollutants which are toxic in industrial waste, for example 4-nitrophenol and dyes. And the oil spills are poisonous for the marine environment. Thus, the environmental problems are more and more serious. Moreover, the awareness of people is gradually increasing. Therefore, their attention has been drawn to solve the water contamination effectively and easily. In addition, searching for new energy sources has become an important topic due to the exhaustion of fossil fuels and air pollution which comes from the combustion of them. Supercapacitors and thermoelectric materials have a broad prospect in application because they are both environmentally friendly.Here, Ni-Ag bimetallic nanoparticles supported on reduced graphene oxide(Ni-Ag@RGO) has been established by using graphene oxide(GO), Ni2+ and Ag+ as precursors, as well as hydrazine hydrate as the reducing agent. The prepared hybrid was further characterized by X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, and transmission electron microscopy, and the magnetic properties were determined by vibrating sample magnetometer. In addition, the catalytic activity of Ni-Ag@RGO has been researched by the reduction of 4-nitrophenol and the photodegradation of methyl orange. The catalytic process was monitored by determining the change in the concentration of the reactants with time using ultraviolet–visible absorption spectroscopy. After completion of the reaction, the catalyst was separated from the reaction system simply under a magnet field and used as the catalyst again to show its recyclability.In addition, GO and nickel nanoparticles were heated without stirring. Consequently, GO has been reduced and reduced graphene oxide(RGO) hydrogel has been assembled. Then the RGO hydrogels were transformed to aerogels via a freeze-drying method. The prepared aerogels were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. Organic dyes, oil and organic solution were used to investigate the absorption capacity of the aerogel. At the same time, the capacitance and stability of aerogel has been researcher as electrode materials for supercapacitors.Moreover, GO has been dispersed in the acid solution of pyrrole. Then, the oxidizing agent was added to trigger the polymerization. The prepared materials were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The thermoelectric properties of materials were investigated by measuring Seebeck coefficient, electrical conductivity and power factor. And we also research the influence of the mass ratio of precursors and the kind of acid by comparing the thermoelectric properties of different materials made by different conditions.