Apatite-Coated Ag/AgBr/TiO₂ Visible-Light Photocatalyst for Destruction of Bacteria

Abstract

Apatite-coated Ag/AgBr/TiO2 was prepared by deposition of Ag as novel metal to generate electron−hole pairs by extending the excitation wavelength to the visible-light region, AgBr, and hydroxy apatite as photosensitive material and adsorption bioceramic, respectively. The energy dispersive X-ray spectrometry clearly showed the presence of Ti, Ag, Ca, and P elements on the surface of catalyst. The bactericidal experiments in dark media indicated that only the novel catalyst shows inhibiting growth of bacteria in this case. A transmission electron microscopy image illustrated that catalyst nanoparticles adhere to the outer membrane of the cell and act as an inhibitor to the nourishment of bacteria from aqueous media. The novel catalyst also showed higher photocatalytic activity compared to Ag/AgBr/TiO2 photocatalyst under visible-light irradiation. The inactivation of E. coli is due to the ability of the catalyst to adhere to the outer cell in addition to destruction of the cell wall by various reactive species.

Silver Nanoparticles

“…Apatite-coated Ag/AgBr/titanium dioxide (TiO 2 ) was prepared by deposition of silver to generate electron−hole pairs by extending the excitation wavelength to the visible-light region, AgBr, and hydroxy apatite as photosensitive material and adsorption bioceramic, respectively (Elahifard et al 2007). In another study, nanoparticle photocatalysts based on silver, carbon, and sulfur-doped titanium dioxide were synthesized by a modified sol-gel method (Hamal and Klabunde 2007).…”

“…(Guin et al 2007). These silver/TiO 2 surfaces had advantageous properties, including visible light photocatalysis, biological compatibility, and antimicrobial activities (Elahifard et al 2007;Seery et al 2007;Hamal and Klabunde 2007). For example, Ag/TiO 2 composite films were prepared by incorporating silver in the pores of titanium dioxide films with an impregnation method via photoreduction (a versatile and convenient process with advantage of space-selective fabrication).…”

“…It was reported that these composite films are promising in application of photocatalysis, antimicrobial and self-clean technologies . In order to synthesize silver nanoparticles on titanium dioxide surfaces, aqueous reduction, photochemical (in-situ photochemical fabrication approach can be used for preparation of metal nanoparticles/polymer nano-composites), liquid phase deposition, and sol-gel methods can be applied (Zheng et al 2008;Elahifard et al 2007;Seery et al 2007;Liu et al 2008;Hamal and Klabunde 2007;Cozzoli et al 2004). Silver nanoparticles with a narrow size distribution were prepared by simple aqueous reduction from silver ions in different molar ratios of titanium dioxide suspensions and NaBH 4 (reducing agent) (NinoMartinez et al 2008).…”

White Light-Activated Antimicrobial Paint using Crystal Violet

“…In order to address this problem, many studies was recently performed to enhance photocatalytic efficiency and white light utilization of TiO2 including using impurity dope and metallization [36][37][38] . Previous studies showed that incorporation of vanadium or silver and bromine extended photocatalytic range of TiO2 from the ultraviolet to the visible region and they showed enhanced antimicrobial activities on bacteria under white light condition 39,40 .…”

Visible-light photocatalytic activity and mechanism of novel AgBr/BiOBr prepared by deposition-precipitation

“…AgBr is an important semiconductor widely used as a photosensitive material in photography and as a photocatalyst for the degradation of pollutants or destruction of bacteria [24,[30][31][32][33][34][35][36][37][38][39][40][41][42][43][44]. Compared with BiOBr [18], AgBr [45] has a narrower band gap and higher visible-light absorption.…”