Comparison of photocatalytic activity and surface friction force variation on Ti-doped hydroxyapatite and anatase under UV illumination

• The adsorption capability of Ti-HAp against IPA was greater than that of anatase.
• Photocatalytic activity of Ti-HAp was inferior to that of anatase.
• The surface friction force variation of anatase was similar to rutile ceramics.
• The surface friction force variation of Ti-HAp was an almost opposite trend against anatase.

Photocatalytic activity and surface friction variation were evaluated on Ti-doped hydroxyapatite (Ti-HAp) and anatase-type TiO2 powders under UV illumination. Although the adsorption capability of Ti-HAp against gaseous 2-propanol (IPA) in the dark was greater than that of anatase, photocatalytic decomposition activity and water adsorption capability of Ti-HAp under UV illumination were inferior to those of anatase. Experiments using powder/epoxy composites revealed that Ti-HAp does not exhibit photocatalytic wettability conversion to a hydrophilic state, which was confirmed on anatase. The surface friction force variation of anatase under UV illumination was similar to previously reported trend for rutile ceramics. That of Ti-HAp exhibited a different trend against anatase, suggesting that its surface was originally more hydrophobic than anatase or cantilever.