The interplay between dopant and a surface structure of the photocatalyst – The case study of Nb-doped faceted TiO2

Anatase nanoparticles, exposing the majority of the {0 0 1}, {1 0 0} and {1 0 1} facets were synthesized and doped with different niobium amount to investigate the self-trapping of the excess electrons and resulting photocatalytic activity. Photocatalyst structure and presence of excess electrons inside the obtained Nb-doped anatase samples was confirmed by the combination of structural and spectroscopic analyses. Only for the {1 0 1} facets, introduced electrons were found to localize on the surface titanium sites, as long as the analysis was performed in the ambient environment. The photocatalytic activity data, studied in the reaction of 4-nitrophenol reduction and phenol oxidation, show that the dopant-introduced electrons might increase photocatalytic activity only for the anatase structures exposing {0 0 1} and {1 0 0} facets. Ultimately, the dopant effect on the photocatalytic activity depends on the exposed facet, which might be investigated for other systems to increase their applicability.