Effect of deposition of Ag nanoparticles on photoelectrocatalytic activity of vertically aligned TiO2 nanotubes

Deposits of Ag nanoparticles on TiO2 nanotubes have been prepared by ex situ photochemical deposition after substrate impregnation in AgNO3 solution. SEM demonstrated that nanoparticles with average size 40 ± 12 nm are uniformly distributed over the substrate without agglomeration. XPS analysis indicated that concentration of precursor electrolyte allows to control the amount of deposited Ag. For the first time the effect of Ag nanoparticles deposition on photoelectrochemical properties, namely on the photocurrent of water decomposition of TiO2 nanotubes was studied. Depending on the illumination (visible vs. UV–visible), the applied bias, and the amount of deposited Ag, the latter may lead either to an increase or a decrease of photocurrent. Possible origins of the positive and the negative effect of Ag deposition on the photoelectrochemical activity of TiO2 are discussed.