Charge distribution between UV-irradiated TiO2 and gold nanoparticles:: Determination of shift in the Fermi level

TiO(2) nanoparticles when subjected to UV irradiation exhibit blue coloration as electrons are stored within the particles. Upon contact with gold nanoparticles, a partial disappearance of the blue color is seen as the stored electrons are transferred from TiO(2) to Au nanoparticles. The charge distribution between the semiconductor and metal nanoparticles causes the Fermi level to shift to more negative potentials. By employing C(60)/C(60)(*-) as a probe-redox couple, we were able to estimate the apparent Fermi levels of TiO(2) and TiO(2)/Au nanoparticles. A Fermi level shift of -22 mV observed for the Au-TiO(2) nanocomposite is indicative of improved charge separation in semiconductor-metal systems and demonstrates its usefulness for improving the efficiency of photocatalytic reactions.