Direct Synthesis of Reduced Graphene Oxide/TiO2 Nanotubes Composite from Graphite Oxide as a High-Efficiency Visible-Light-Driven Photocatalyst.

Synthesis of reduced graphene oxide/TiO2 nanotubes (rGO/TNTs) composite is being attended. However, the synthesis of rGO/TNTs composite directly from graphite oxide with a greener approach is still challenging. In this study, we directly synthesized rGO/TNTs composite by a simple method from graphite oxide and titanium dioxide nanotube (TNTs) powder without involving any assistant agents. The formation of the graphene oxide (GO) was confirmed by X-ray diffraction (XRD) pattern, transmission electron microscope (TEM) image, Fourier-transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Besides, photoluminescence analysis (PL) was conducted to determine the defects of materials. The methylene blue (MB) photodegradation efficiency under visible light of rGO/TNTs composite achieved 80% after 180 min. In addition, the key of the photocatalytic mechanism of rGO/TNTs under visible light was systematically investigated via trapping experiments.

Controlled Formation of Silver Nanoparticles on TiO2 Nanotubes by Photoreduction Method.

In this paper, we surveyed the effect of the concentration of AgNO3 solution and the time of photoreduction on the formation of Ag nanoparticles supported on TiO2 nanotubes (Ag/TNTs) were synthesized by photoreduction method. Their morphology and crystal structure were determined by Transmission Electron Microscopy images (TEM), X-ray Diffraction (XRD) and Energy-dispersive X-ray spectroscopy (EDX) data. Results show that the amount of Ag nanoparticles supported on TNTs could be controlled by changing of the illumination time (photoreduction time) and the concentration of AgNO3 solution. Besides, the annealing temperature has a direct influence on the morphology of TNTs. Especially, the nanotubes transformed into nanorods at 500 °C for 2 hours.

The Effect of Acid Treatment and Reactive Temperature on the Formation of TiO2 Nanotubes.

TiO2 nanotubes (TNTs) were synthesized by a hydrothermal method from commercial TiO2 in NaOH followed by HCl washing. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmitting electron microscopy (TEM), and Brunauer-Emmet-Teller (BET) measurements. The untreated acid samples (pH ~ 12) don't appear nanotubes structure, while acid-treated samples until the pH reached around 2 have approximate diameters of nanotubes of 10 nm. The samples reaction temperature at 135 °C appear nanotubes structure while the samples reaction temperature at 150 °C have combination of the nanotubes and the samples treatment temperature at 170 °C appear both nanotubes structure and particles clumping together. The surface area of the TNTs was 83,5 m2/g while the surface area of commercial TiO2 particles was 41 m2/g.