Enhanced Photocatalytic Activity of TiO₂ Nanoparticles Supported on Electrically Polarized Hydroxyapatite

Fast recombination of photogenerated charge carriers in titanium dioxide (TiO2) remains a challenging issue, limiting the photocatalytic activity. This study demonstrates increased photocatalytic performance of TiO2 nanoparticles supported on electrically polarized hydroxyapatite (HA) films. Dense and thermally stable yttrium and fluorine co-doped HA films with giant internal polarization were synthesized as photocatalyst supports. TiO2 nanoparticles deposited on the support were then used to catalyze the photochemical reduction of aqueous silver ions to produce silver nanoparticles. It was found that significantly more silver nanoparticles were produced on polarized HA supports than on depolarized HA supports. In addition, the photodegradation of methyl orange with TiO2 nanoparticles on polarized HA supports was found to be much faster than with TiO2 nanoparticles on depolarized HA supports. It is proposed that separation of photogenerated electrons and holes in TiO nanoparticles is promoted by the internal polarization of the HA support, and consequently, the recombination of charge carriers is mitigated. The results imply that materials with large internal polarization can be used in strategies for enhancing quantum efficiency of photocatalysts.