Hydroxyapatite/Anatase Photocatalytic Core–Shell Composite Prepared by Sol‒Gel Processing

The conditions for preparing hydroxyapatite/anatase Ca 10 (PO 4 ) 6 (OH )2 /TiO 2 nanocomposites with a core–shell structure by sol‒gel processing have been optimized. The photocatalytic activity of these nanocomposites is close to that of the commercial photocatalysts based on titanium dioxide (precursor Ti(O But ) 4 concentration 40 vol %, hydroxyapatite/TiO 2 sol ratio 1: 2, annealing temperature 500°C). The photocatalytic activity of hydroxyapatite/TiO 2 composites with different anatase contents has been estimated for the first time from the singlet oxygen yield. It is shown that the degree of modification of apatite particle surface affects significantly the structural characteristics of the hydroxyapatite/TiO 2 composite. An increase in the relative anatase content reduces the sizes of apatite crystallites and increases their specific surface.