Spectroelectrochemical characterization of euhedral anatase $TiO_2$ crystals : implications for photoelectrochemical and photocatalytic properties of {001} {100} and {101} facets

Tailored crystals of anatase TiO2 have been synthesized using a hydrothermal method with hydrofluoric acid and sodium fluoride as capping agents. Titanium dioxide in the form of sheets, tetragonal truncated bipyramids, cuboids and belts offer different exposed facets: {001}, {001}/{101}, {001}/{100} and {100}, respectively. The strongest oxygen adsorption was observed for crystals with exposed {001} facets. Adsorbed fluorides also improve oxygen adsorption. Our spectroelectrochemical (SE-DRS) measurements of density of electronic states (DOS) revealed that the energy of conduction band edge increases in the order: {101} generation) also depends on the exposed facets and increases in the order: cuboids, sheets, tetragonal truncated bipyramids, belts. Furthermore, fluoride ions drastically decrease the photocatalytic production of TAOH.