Preparation And Photocatalytic Properties Of TiO 2 - Composite Nanomaterials

Photocatalytic technology is an effective way to solve the environmental crisis. TiO2being photocatalyst has extensively studied due to its physical and chemical stability, high reactity,low toxicity and cheapness. However, TiO2has low photocatalytic efficiency because of the wide band cap(Eg=3.2eV), which lead to the low utilization of visible light and high recombantion rate of photogenerated electrons-holes. It will be a key factor to utilize solar energy effcetivly that looking for new photocatalyst and extending photoresponse area of photocatalyst. We mainly use the new carbon material, graphene(GR), to modified TiO2as the new graphene-based photocatalyst. The obtained nanocomposites were characteristiced by XRD, FTIR, Raman, XPS, SEM, TEM, HRTEM, EDS, UV-vis and PL, and were evaluated the photocatalytic activity by photodegradation of methylene blue and hydrogen evolution by water splitting. Specifics as follows:1. Graphite oxide (GO) poweder was obtained by modified Hummer method, then the P25-GR nanocomposite was fabricated with P25and graphite oxide through a hydrothermal method. The P25-GR nanocomposites performed better photocatalytic activity in photodagradation of Methylene blue and hydrogen evolution by water splitting, of which the highest degradation rate of MB was99%and hydrogen evolution efficiency was1.29mmol/g. The composites also did well in reusing experiment.2. TiO2-GR nanocomposite was synthesized by tetrabutyl titanate as precursor through a a one-step hydrothermal method, that the pure antase TiO2nanoparticals were growed on the graphene surface. Compared to P25-GR, TiO2-GR has better optical properties, which due to the better photocatalytic activity in degradation of MB and hydrogen evolution, that is, almost100%degradation rate of MB at6hours and1.35mmol/g at hydrogen evolution experiment.3. P25-GR nanocomposite was fabricated with P25and graphite oxide through a hydrothermal method, and then Ag nanoparticals(Ag NPs) was assembled in P25-GR (Ag-P25-GR, APG) under microwave-assisted chemical reduction. The results showed that Ag NPs were well dispersed on the surface of PG with metallic state. The ternary Ag-P25-GR (APG) nanocomposites possessed the extended light absorption range and more efficient charge separation properties compared to binary P25-GR. Methylene blue photodegradation experiment proved that surface plasmon resonance (SPR) phenomenon had an effect on photoreaction efficiency. The corresponding hydrogen evolution rate of APG was2.12mmol/g, which was much better than pure P25and PG in the same test condition.4. Ag-TiO2-GR(ATG) nanocomposite was synthesized tetrabutyl titanate as precursor through a a one-step hydrothermal method., that the Ag and pure antase TiO2nanoparticals were growed on the graphene surface at the same time. The results showed that ternery ATG samples have better optical properties compared to APG samples because of the synergistic effect of SPR phenomenon and chemical in-situ composite, that is,2.52mmol/g at hydrogen evolution experiment.5. P25-GR nanocomposite was fabricated with P25and graphite oxide through a hydrothermal method, and then Cu nanoparticals (Cu NPs) was assembled in P25-GR (Cu-P25-GR, CPG) under microwave-assisted chemical reduction. Cu NPs is tend to grown at surface of P25nanoparticals which was different with Ag NPs cause Cu NPs is easy oxided by GO. The results showed that ternery CPG samples have better optical properties compared to PG samples because of the SPR phenomenon, that is,2.52mmol/g at hydrogen evolution experiment. CPG samples also have better photocatalytic activity than APG samples because of the presence of CuO.Most of the content of this paper are mainly concentrated in preparation and modification of graphene-based TiO2photocatalyst to enhance its photocatalysis performance. We discussed the reason that why graphene could improve photocatalytic activity of TiO2and studied the different photocatalytic performance of graphene-based TiO2nanomaterials by different preparation method. We expect our work could give a new train of thought on exploration of GR-based nanocomposites.