Graphene Based Materials: Praperation And Application In Photoelectric Conversion

The utilization of solar energy is one of the practicable way to solve theenvironmental pollution and energy shortage, and the photoelectric conversion isthe most important form to utilize solar energy. The appearnce of graphenepormoted the development of photoelectric technology. Graphene is amonolayer of carbon atoms packed into a dense honeycomb crystal structure.Due to its unusual and intriguing properties, graphene has attracted tremendousattention from both the method of preparation and its application since it wasfirst reported by Novoselov and Geim in2004. In this work, a series of grapheneand graphene composites have been obtained via different methods. The certainproperties of these products have been studied. The principal results of thedissertation are discussed as follows:1. Reduction of graphene oxide （GO） has been achieved by an in-situphotoelectrochemical method in a DSSC assembly, in which the semiconductorbehavior of the reduced graphene oxide （RGO） is controllable. To improve thelight utilization efficiency, a back reflection film and TiCl4modification wereinvovled to modify the TiO2photoanode. Under illumination the GO film, whichassembled in the DSSC assembly as the counter electrode, was partly reduced.The reduction degree of RGO was controlled by the reduction time and the reduction potential of I–/I–3couples. An optimized photoelectrochemicalassembly is promising for modulating the reduction degree of RGO andcontrolling the band structure of the resulting RGO by.2. A one-step electrochemical approach for synthesis of Pt/RGO wasdemonstrated. GO and chloroplatinic acid were reduced to RGO and Ptnanoparticles （Pt NPs） simultaneously, and Pt/RGO composite was deposited onthe fluorine doped SnO2glass during the electrochemical reduction. The Pt/RGOcomposite was characterized, which confirmed the reduction of GO andchloroplatinic acid and the formation of Pt/RGO composite. Results of cyclicvoltammetry and electrochemical impedance spectroscopy measurementsshowed that the composite electrode had higher charge transfer rate and lowercharge transfer resisitence, respectively. The composite electrode had proved tohave better performance in DSSC than Pt NPs electrode, which showed thepotential application in energy conversion.3. Polyvinylpyrrolidone （PVP） modified graphene/TiO2composite wasprepared by hydrothermal method. The PVP-modified graphene had betterdistribution, so the graphene/TiO2composite had better photoelectric property.The results of characterization showed that GO was reduced into graphene andnano TiO2particles were dispersed on the graphene uniformly. Ti-O-C bond wasformed between graphene and TiO2with the existense of PVP. The analysisproved that the composite had lower electron transfer resistence. Thus, thecomposites had better photoelectric conversion performance. Besides,graphene/TiO2had visible light respose property, which means grapheneenlarged the photoelectric response region of TiO2. The photo catalytic acticityfor degrading methyl orange was studied. The composites showed better performance than TiO₂particles.