Fabrication Of Graphene-based Nanostructures And Photocatalytic Decomposition Of Water Into Hydrogen

With the growing demands for clean energy of human society, photocatalytic water splitting for hydrogen production has gained extensive attention of researchers. Graphene has excellent electron transfer property due to its large ? conjugate structure, and it shows high absorption intensity in visible light range. These properties can improve the photocatalytic properties of graphene composite materials. Bi₂MO₆?M=W, Mo? materials are semiconductors with perovskite structure, and their structure makes them have great potential application in photocatalysis. Hence, researches on the preparation of graphene/Bi₂MO₆?M=W, Mo? composite materials and investigating their photocatalytic water splitting for hydrogen production are important and valuable.In this thesis, graphene was prepared by modified Hummers method. Graphene/Bi₂WO₆ composite nanofibers, nanobelts and graphene/Bi₂MoO₆ composite nanofibers were prepared via electrospinning process. Graphene/Bi₂WO₆ composite clews were fabricated by hydrothermal reaction. The samples were characterized by X-ray diffraction?XRD?,scanning electron microscopy?SEM?, energy dispersive X-ray spectrometry?EDX?,transmission electron microscopy?TEM?, X-ray photoelectron spectroscopy?XPS?, UV-Vis diffuse reflection spectroscopy?UV-Vis DRS? and Photoluminescence spectroscopy?PL?. In addition, the photocatalytic H2 production activity of the samples were also tested, the H2 production efficiencies of the same substance with different morphologies are investigated,and the optimum doping ratio of graphene were researched. The results show that the optimum doping ratio of graphene in graphene/Bi₂WO₆ composite nanofibers, nanobelts,clews and graphene/Bi₂MoO₆ composite nanofibers are 6 %, 2 %, 5 % and 5 %, respectively;and the corresponding H2 yield are 935.27, 492.21, 716.03 and 794.72 ?mol·h^-1?The using amount of photocatalyst is 0.1 g?, respectively, which are 5.8, 2.5, 6.2, and 2.9 times higher than the H2 yield by using pure counterpart Bi₂WO₆ with the same morphologies. The photocatalytic water splitting mechanism of graphene/Bi₂MO₆?M=W, Mo? are also proposed.These new findings lay foundation for the future research of graphene/semiconductor composite materials.