Effects of MoO modification on photocatalytic activity of hydroxyapatite and Ti-doped hydroxyapatite

Abstract Titanium-doped hydroxyapatite (Ti-HAp, (Ca 10-2 x , Ti x , □ x ) (PO 4 ) 6 (OH) 2 , □: defect in Ca site) and hydroxyapatite (HAp, Ca 10 (PO 4 ) 6 (OH) 2 ) powders were modified with an ethanol solution of molybdenyl acetylacetonate (MoO 2 (C 5 H 8 O 2 ) 2 ) using chemisorption calcination cycle (CCC) technique, which provides metal oxide clusters. Their photocatalytic activity under UV illumination was evaluated by the decomposition of gaseous 2-propanol. The photocatalytic activity of the Mo-modified Ti-HAp samples increased concomitantly with increasing Mo concentration up to 0.72% against P. The highest photocatalytic activity of Mo-modified Ti-HAp was about 13 times higher than that of Ti-HAp. The signal appearance of Mo(V) in electron spin resonance spectra and the decrease of photoluminescence intensity suggest electron transfer from the Ti-hybridized band to the MoO x cluster, which suppresses recombination of the photoinduced electron and hole pairs. The photocatalytic activity of Mo-modified HAp samples was attributed to HOMO–LUMO excitation of MoO x cluster.