Photodegradation of Sulforhodamine-B Dye in Platinized Titania Dispersions under Visible Light Irradiation:  Influence of Platinum as a Functional Co-catalyst

Abstract

The photooxidative degradation of sulforhodamine-B dye (SRB) taking place in visible-light illuminated platinized titania dispersions is revisited to examine the influence of metallic platinum doped on TiO 2 particles (Degussa P25 titania) by photocatalytic deposition from a hexachloroplatinic acid solution. The various TiO 2 / Pt specimens were characterized by transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy (XPS). The self-photosensitized degradation of SRB mediated by TiO 2 /Pt specimens is 3-fold faster than that occurring on TiO 2 alone under visible light irradiation and under otherwise identical conditions. That is, the TiO 2 /Pt system exhibited greater catalytic activity than P25 TiO 2 alone, which earlier proved to be an effective photocatalyst in the degradation of dyes under visible illumination. A reaction mechanism is proposed on the basis of a series of experiments that included spintrap electron spin resonance (ESR) spectral results, measurement of quantities of H 2 O 2 formed, chemical oxygen demand (COD Cr ), and total organic carbon (TOC) data. The platinum dopant acts as an electron sink from which molecular oxygen scavenges the electrons to yield superoxide radical anions (O 2 -• ) first and then • OH radicals, which are known to cause the ultimate self-destruction of the SRB dye.

Preparation and visible-light activity of silver vanadate for the degradation of pollutants

“…In addition, the extra small particle on the surface of Ag 3 VO 4 in excess vanadium contained Ag 0 species. According to the reported work [20][21][22], it is quite possible that appropriate amount of Ag 0 species on the surface of the catalyst mainly act as electron traps, enhancing the electron-hole separation, leading the higher photocatalytic activity. This point was further proved by the determination of photoluminescence of the samples.…”

Ag/AgBr/TiO2 Visible Light Photocatalyst for Destruction of Azodyes and Bacteria

“…[1][2][3][4][5] The main drawbacks of low quantum yields and the lack of visible light utilization, however, hinder its practical application. To handle these problems, numerous studies have recently been performed to enhance the photocatalytic efficiency and visible light utilization of TiO 2 , which include impurity doping, [6][7][8][9] metallization, [10][11][12][13][14][15] and sensitization. 16,17 According to these published works, the deposition of the metal on visible light catalysts highly improved its photoefficiency through the Schottky barrier CB electron trapping and consequent longer electron-hole pair lifetimes.…”

Preparation and Visible‐Light Photocatalytic Activity of Ag3VO4 Powders.

“…However, the fast recombination rate of photogenerated electron-hole pairs hinders the commercialization of this technology [5,6]. Furthermore, TiO 2 only active under UV irradiation limits its application [7]. Numerous studies have attempted to develop visible-light-driven photocatalysts in order to utilize solar energy and indoor light efficiently [8][9][10][11][12].…”