LaO1.5 surface modification of titanium-substituted hydroxyapatite photocatalyst and effects on 2-propanol photocatalytic decomposition mechanisms

Abstract After using impregnation to prepare LaO1.5 cluster modified titanium-substituted hydroxyapatites (Ti-HAps), photocatalytic decomposition activity on gaseous 2-propanol (IPA) under UV illumination was increased by three times through LaO1.5 modification while preserving its high adsorption capability for organic compounds. First-principles molecular dynamics simulations and electronic structure investigations revealed that photo-excited electron transfer from Ti to La does not occur in LaO1.5-modified Ti-HAp. Rather, the results implied that its photocatalytic activity increase is related to gaseous IPA and O2 adsorption properties. The IPA dissociative adsorption at Ca sites was observed in LaO1.5-modified Ti-HAp. The obtained electronic structure suggests that the adsorbed IPA molecule can be oxidized easily and directly. Moreover, O2 molecule adsorption and desorption were observed, which implies charge recombination suppression and that O2 - radical can be involved in IPA decomposition. Results demonstrate that control of the adsorption properties of target molecules by cluster modification can enhance photocatalytic decomposition activity.