The electro-catalytic activity of nanostructured nickel titanate (NiTiO 3 ) powders synthesized by a Sol-Gel process was evaluated by means of the electro-oxidation of methanol in alkaline media. In order to correlate the structural, vibrational, morphological and optical properties of the NiTiO 3 powders with their electrochemical activity they were characterized by X-ray diffraction (XRD), Raman spectroscopy, Transmission Electron Microscopy (TEM) and Diffuse Reflectance Spectroscopy (DRS). The powders are formed by nanoparticles of the order of 25 nm. It is shown that the electro-oxidation of methanol in alkaline media is possible in the presence of nanoparticles of this non-noble metal compound, as demonstrated by the current-versus-potential characteristics obtained as a function of methanol concentration. It is shown that the activated Ni atoms at the NiTiO 3 nanoparticles cause a great increase of the electro-oxidation rate of methanol under alkaline conditions. Therefore, this opens the possibility that a layer of nanostructured NiTiO 3 might be used as a catalyst for direct alkaline methanol fuel cells.
Boron- and cerium-doped titania (Anatase) were prepared via sol-gel method. Phase composition and morphology were assessed by X-ray diffraction (XRD), scanning electronic microscopy (SEM), BET, diffuse reflectance spectra (DRS), and XPS. Photo-electrochemistry of these materials, deposited onto fluorine-doped SnO2 (FTO), was investigated in acid and acid-containing methanol. The boron-doped sample showed the best opto-electronic properties among the investigated samples. On the other hand, the cerium-doped titania samples annihilate to a certain extent the titania surface states, however, photogenerated charge separation was limited, and certainly associated to surface Ce3+/Ce4+ species. The substitutional effect of boron ions for O sites and interstitial sites was confirmed by XRD and XPS analyses.
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