The effect of Fe segregation on the photocatalytic growth of Ag nanoparticles on rutile TiO2(001)

Abstract The photocatalytic growth of silver nanoparticles (AgNPs) on rutile TiO 2 (001) and Fe-modified rutile TiO 2 (001) monocrystals was investigated. Various amount of Fe was segregated in a controlled way from the doped TiO 2 substrates in ultra-high vacuum conditions resulting in low- medium- and high- content of Fe on TiO 2 substrates. AgNPs were grown on pristine TiO 2 and substrates containing Fe by photoreduction of Ag + ions under UV illumination. It was found that the size of AgNPs was larger on Fe/TiO 2 than on TiO 2 while the surface density exhibited the opposite behavior – a large number of AgNPs were present on the TiO 2 surface but only a few AgNPs were visible on the Fe/TiO 2 substrates. The reason for the differences in size and number of AgNPs on TiO 2 and Fe/TiO 2 is the limited access of Ag + to the TiO 2 surface caused by the large number of Fe grains segregated onto the TiO 2 surface. Another possible reason for the various AgNPs morphologies is alteration in the mechanism of Ag + photoreduction caused by iron present as Fe 3+ ions and by newly formed AgNPs playing the role of electron traps. The surface elemental analysis of the investigated materials was performed with the use of X-ray photoelectron spectroscopy (XPS) and confirmed the composition of AgNPs/Fe/TiO 2 systems. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed sizes, morphology and distribution of the nanostructures.