Enhancement of Efficient Ag–S/TiO₂ Nanophotocatalyst for Photocatalytic Degradation under Visible Light

Abstract

A new photocatalyst (Ag−S/PEG/TiO 2 ) was synthesized by adding polyethylene glycol (PEG) to an efficient Ag−S/TiO 2 photocatalyst, to obtain a photocatalyst that is highly active under visible light. In addition to Ag−S/PEG/TiO 2 , Ag−S/TiO 2 and pure TiO 2 were prepared to compare their properties and activities. Specifically, the morphologies and microstructures of the nanophotocatalysts were characterized by means of powder X-ray diffraction (XRD), N 2 adsorption−desorption measurements, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) microanalysis, transmission electron microscopy (TEM), UV−visible diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Moreover, to evaluate their activities, the synthesized powders were used for the degradation of acid orange 7 (AO7) and methylene blue (MB) azo dyes in aqueous solution under low-voltage lightemitting diodes (LEDs) as the visible-light source. It was found that addition of PEG to Ag−S/TiO 2 increases the photodegradation of AO7 and MB by about 28.82% and 24.24%, respectively, in comparison with Ag−S/TiO 2 without PEG addition.

Hydrogen peroxide‐assisted photocatalysis under solar light irradiation: Interpretation of interaction effects between an active photocatalyst and H2O2

“…An Ag‐S/PEG/TiO 2 nanophotocatalyst was synthesized using a one‐step sol‐gel technique similar to that described in our previous work . Titanium tetraisopropoxide (TTIP, ≥ 98 %, Sigma‐Aldrich) was used as the origin of titanium, whereas precursors for silver and sulphur were silver nitrate (AgNO 3, from Merck KgaA, Darmstadt, Germany) and thiourea (CH 4 N 2 S, from Merck KgaA, Darmstadt, Germany), respectively.…”

“…Therefore, bare TiO 2 cannot utilize the majority of the sunlight reaching the surface of the earth since 43 % of solar energy lies in the wavelength range of visible light . Many attempts have been made to move the inception of the photo‐excitation of TiO 2 from the ultraviolet to the visible region . For this purpose, an efficient strategy is to dope TiO 2 with transition metal or non‐metal elements .…”

“…As a the result of the photocatalyst activation, reactive oxygen species (ROS, in particular, OH°, HO 2 °, HO 2 ° _ , and H 2 O 2 ) are generated, and they are capable of degrading and mineralizing many organic water pollutants that are produced . Thus, in this work, a previously investigated photocatalyst (i.e., Ag‐S/PEG/TiO 2 ), as a visible light sensitive photocatalyst, was synthesized and subjected to natural solar light irradiation experiments.…”

E. coli inactivation by visible light irradiation using a Fe–Cd/TiO 2 photocatalyst: Statistical analysis and optimization of operating parameters

“…Many attempts have been made to shift the onset of TiO 2 absorption from the ultraviolet to the visible region, while maintaining a large reactive surface [11,12]. One of the most effective methods is doping of TiO 2 with different metal ions, such as Fe 3+ and Cd 2+ [13][14][15][16][17][18].…”

Significant Enhancement of the Photoelectrochemical Activity of Nanoporous TiO 2 for Environmental Applications

“…Various techniques have been employed to narrow the band gap of TiO 2 , including doping with non-metal elements, which is the most common procedure for augmenting visible light photocatalytic activity. The doping of TiO 2 with C, N, F and S has demonstrated improvements in its UV-visible light response [27][28][29][30][31][32]. However, recent theoretical and experimental studies have raised questions in regard to this strategy and its suitability as the most efficient approach.…”