Electrochemical Properties of Hydroxyapatite Crystal Surfaces on Anatase Photocatalysts

Abstract

Hydroxyapatite (HAp) was crystallized on anatase titanium dioxide (TiO 2 ) photocatalytic crystals or their thin films using of a pseudo-body solution method, and electrochemical properties of the HAp-adhered anatase TiO 2 photocatalytic surfaces were discussed. Decomposition rates of methylene blue were faster for the HAp-adhered anatase TiO 2 photocatalysts, although specific surface areas were smaller than those for the commercial anatase TiO 2 ones. Surface potential dispersions on the HApadhered anatase TiO 2 thin films before and after an ultraviolet light irradiation were measured by an atomic force microscopy. Changes in the color of leucocrystalviolet mixed in the HApadhered anatase TiO 2 photocatalysts or the commercial anatase TiO 2 ones with experimental durations were compared. Movements of electrons from the anatase TiO 2 photocatalytic surfaces to the HAp, crystals and oxidizing reactions on the HAp-adhered anatase TiO 2 photocatalytic surfaces in the dark were discussed on the basis of these experimental results.

Oxidation – Reduction Potentials of Hydroxyapatite - Adhered Photocatalysts

“…1 in ref. [6]). Shape of HAp particles was sphered agglomerates that are constituted by a lot of plate -like crystals (see Fig.…”

“…HAp crystals were precipitated on anatase TiO 2 thin films formed on a slide glass, and the surface potentials of their substrates were measured by use of an atomic force microscopy. The surface potentials at the interfaces between HAp crystals and anatase TiO 2 became higher by irradiation of UV light [6].…”

“…Although the sample mixed with anatase TiO 2 photocatalysts was kept white, the sample mixed with HApadhered anatase TiO 2 photocatalysts changed to blue. Therefore, it is considered that the oxidation reactions from LCV, of which color is white, to crystalviolet, of which color is violet, occur in the dark for the case of HApadhered anatase TiO 2 photocatalysts [6]. In this way, the qualitative evaluations about electrochemical properties for HAp crystals were indicated.…”

Preparation of porous titanium phosphate glass-ceramics for NH3 gas adsorption with self-cleaning ability

“…7,8 Among them, hydroxyapatite (HAp)/TiO 2 composites show good adsorption and photodecomposition properties for polluting materials such as bacteria and toxic chemical compounds. [9][10][11][12][13] However, the chemical degradation of HAp under acidic conditions limits the industrial application of the HAp/TiO 2 composites. Fluorine-substituted HAp and TiO 2 composites have been investigated to improve the chemical degradation of HAp.…”

Structures and Photocatalytic Properties of Crystalline Titanium Oxide‐Dispersed Nanoporous Glass–Ceramics

“…This has promoted great interest in developing a chemically stable adsorbent with a high photodecomposition property. Hydroxyapatite (HAp)/TiO 2 composites show good adsorption and photodecomposition properties for pollutant materials such as bacteria and toxic chemical compounds 11–15 . However, the chemical degradation of HAp under acidic condition limits the industrial applications of HAp/TiO 2 composites.…”