Preparation And Properties Of Reduced Graphene Oxide-Metals/Metal Oxides Nanocomposites

Due to its excellent properties, such as optical property, electrical property, mechanical property and thermal property, graphene has been widely applied to many fields. Noble metal nanoparticles loaded graphene composites attracts extensive attentions due to their high catalytic activity in photocatalytic hydrogen evolution and chemical catalysis. But its application was limited because of high cost and low storage of noble metals. Therefore, it is important to look for cheap metal cocatalysts as alternatives. In this dissertation, cheap transition metals/transition metal oxides were chosen to replace noble metal as the cocatalysts, a series of RGO-metals/metal oxides nanocomposites were designed and prepared. Photocatalytic activities for hydrogen evolution from water reduction and catalytic performanco towards the reduction of 4-nitrophenol (4-NP) over various catalysts were investigated, and the catalytic mechanism of composites was further discussed according to the results of fluorescence spectroscopy and electrochemical impedance spectroscopy. The main results are summarized as follows.Cu2O loaded reduced graphene oxide (Cu2O/RGO) was prepared via a one-step in-situ reduction method. Composition and structure of the Cu2O/RGO were characterized by X-ray diffraction, high resolution transmission electron microscope and X-ray photoelectron spectroscopy. With Cu2O as the cocatalyst, eosin Y (EY) and rose bengal (RB) as co-sensitizers, the activity of hydrogen evolution over the Cu2O/RGO dramatically increased and achieved a maximum when the loading amount of Cu on the RGO was about 3 wt%. Compared to that of the pure RGO, the activity was enhanced by up to 7.3 times. It could be even comparable to that of the Pt/RGO under the same reaction conditions. This work showed a possibility for the utilization of Cu2O as an alternative for noble metals (such as Pt) due to its low cost and high performance in photocatalytic hydrogen production.CuxNiy bimetallic nanoalloys loaded graphene nanohybrids (CuxNiy/G) were prepared via a facile coreduction process. Composition and structure of the CuxNiy/G were characterized by X-ray diffraction, high resolution transmission electron microscope and X-ray photoelectron spectroscopy. With CuxNiy bimetallic nanoalloy as the co-catalyst, eosin Y (EY) and rose bengal (RB) as co-sensitizers, the activity of hydrogen evolution over the CuxNiy/G dramatically increased and achieved a maximum when the molar ratio of Cu2+ to Ni2+ was 1: 3. Compared with that of the pure graphene, the activity was enhanced by up to 8.2 times. It could be even comparable to that of the Pt/G under the same reaction conditions. This work demonstrated that it is possible to enhance catalytic activity of the graphene for hydrogen production with the CuxNiy bimetallic nanoalloys as the noble-metal-free cocatalyst.Cu nanoparticles loaded reduced graphene oxide (Cu/RGO) was prepared via a one-step in-situ reduction method. Composition and structure of the Cu/RGO were characterized by X-ray diffraction, transmission electron microscope and X-ray photoelectron spectroscopy. Catalytic performance of the Cu/RGO towards the reduction of 4-nitrophenol (4-NP) to 4-aminophenol(4-AP) was investigated. The results showed that Cu nanoparticles as the cocatalyst could significantly enhance the catalytic activity of RGO.