Photoelectrochemical processes at interfaces of nanostructured TiO 2/carbon black composites studied by scanning photoelectrochemical microscopy
Por:
Rincón M.E., Trujillo M.E., Ávalos J., Casillas N.
Publicada:
1 ene 2007
Resumen:
The local photoelectrochemical response of TiO 2/carbon black photocatalysts was studied by means of scanning photoelectrochemical microscopy performed under UV illumination and external polarization. Catalysts obtained by sol-gel techniques showed a uniform response that improved under anodic polarization, in contrast to the non-uniform response of mixtures that show enhancement under cathodic polarization. To explain the differences in photoelectrochemical activity, we performed electrochemical and capacitive studies under dark condition, finding a larger positive shift in the rest potential of sol-gel composites plus evidence of Fermi-level pinning. We propose the last is related to the presence of carbon states with a strong acceptor character formed during the sol-gel synthesis. An energy band diagram of the composites were sketched based on the data obtained. © Springer-Verlag 2007.
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