Electrochemical fabrication of TiO₂ -Au nanocomposites

Nanocomposites comprised of electrosynthesized/annealed TiO₂ on indium tin oxide substrates, using the electrogeneration of base method, followed by electrodeposited gold clusters are presented, and their photoelectrochemical response is examined. The TiO₂ films are nodular with a rough morphology. Gold nanoparticles were electrodeposited onto the electrogenerated TiO₂ with galvanostatic pulses. A step photoresponse analysis was employed to characterize the photoelectrochemical behavior of three different forms of the TiO₂-Au composite: (i) TiO₂ decorated with Au nanoparticles, TiO₂/Au, (ii) TiO₂ with embedded Au nanoparticles in a sandwichlike fashion, TiO₂/Au/TiO ₂, and (iii) TiO₂ with embedded and decorated Au nanoparticles, TiO₂/Au/TiO₂/Au. The TiO₂/Au composite resulted in the highest photocurrent response under UV irradiation and in a broadening of the photocurrent response to the visible region, although with successive testing a decrease in the photocurrent response was observed. The photoresponse of the buried Au nanoparticles, TiO₂/Au/TiO ₂, was slightly lower compared to Au decorating the TiO₂ electrosynthesized surface, TiO₂/Au, but significantly higher than pristine electrosynthesized TiO₂.