Hydroxyapatite/titanium dioxide nanocomposites for controlled photocatalytic NO oxidation

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Hydroxyapatite/titanium dioxide nanocomposites for controlled photocatalytic NO oxidation (EN)

Mitsionis, A. (EN)

Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας (EL)
Mitsionis, A. (EN)

Biphasic photocatalytic powders consisted of hydroxyapatite (HA) and titanium dioxide (TiO(2)) were prepared by precipitation of HA in presence of TiO(2) (Evonik-Degussa P25). Depending on the volume ratio between HA and TiO(2) in the initial solution the materials showed different textural properties. Aggregates consisted of spherical particles were formed at low HA/TiO(2) ratio, while the decrease of the TiO(2) amount resulted in formation of needle and lath like particles. The specific surface area (ssa) of the composites was higher than the ssa of the pure components and increased with the decrease of the TiO(2) amount. The novel materials exhibited excellent activity in photocatalytic NO oxidation, while the activity in NO(2) removal, either by oxidation or by adsorption to the HA. was extremely low for the composites with volume ratio V(HA)/V(TiO2) more than 1. The selective behavior of these composites towards the two steps of the NO oxidation process was related to the preparation procedure followed. The composite with 50% (v/v) TiO(2) revealed higher center dot OH formation ability and photocatalytic activity in overall NO(x) removal than the pure TiO(2) component that was ascribed to the specific V(HA)/V(TiO2) ratio and growth of HA on the TiO(2) surface. (C) 2011 Elsevier B.V. All rights reserved. (EN)

hydroxyapatite (EN)

Applied Catalysis B-Environmental (EN)



Elsevier (EN)

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