Highly efficient solar photocatalytic degradation of a textile dye by TiO2/graphene quantum dots nanocomposite

Abstract

Herein, two sunlight responsive photocatalysts including TiO 2 nanoparticles (NPs) and TiO 2 /graphene quantum dots (GQDs) nanocomposite for degrading a textile dye, Reactive Black 5 (RB5), were prepared. The results showed that 100% of 50 ppm RB5 could be degraded by TiO 2 NPs and TiO 2 /GQDs within 60 and 30 min sunlight irradiation, respectively. Hence, much better photocatalytic activity in degradation of RB5 was achieved by TiO 2 /GQDs under sunlight irradiation compared with pure TiO 2 NPs due to its lower band gap (2.13 eV) and electron/hole recombination rate. The photocatalytic degradation mechanism of RB5 by TiO 2 NPs was elucidated by adding some scavengers to the solution. The main reactive species contributing to RB5 degradation were surface hydroxyl radicals. The first-order solar degradation rate constant of RB5 for TiO 2 / GQDs is greater than that of TiO 2 NPs under sunlight illumination.

Photocatalytic degradation of Rhodamine B dye using low‐cost pyrofabricated titanium dioxide quantum dots‐kaolinite nanocomposite

“…The surface hydroxyl groups (or H 2 O) on the photocatalyst's surface might catch the photo‐induced holes at the same time, producing hydroxyl radicals ( • OH) 63 : …”

“…The relationship among the potentials of valence and conduction bands, band gap ( E g ) and the energy of free electrons of a semiconductor ( E e ) can be calculated by the following Equations and 63 : where E VB and E CB are the potential energy (eV) of the valence and conduction bands, respectively. X is the absolute electronegativity of a semiconductor TiO 2 ‐QDs and E e is the energy of free electrons in a standard hydrogen electrode (4.5 eV).…”

Recent progress on the use of graphene-based nanomaterials in perovskite solar cells

“…66,[74][75][76][77][78][79][80][81] Also, GBNs increases the exibility of these cells. Due to the unique properties of GBNs, they have been used in numerous elds and practical applications, [82][83][84] in addition to PSCs, including in freshwater production by solar desalination, [85][86][87][88] degradation of pollutants, [89][90][91][92][93] oil/water separation, [94][95][96] and in medicine as antibacterial, 97-100 antiviral, 101 and anticancer agents, 102 biosensors, 103,104 and fuel cells 105 (see Fig. 4).…”

S‐g‐C3N4/N−TiO2 @PTFE Membrane for Photocatalytic Degradation of Tetracycline

“…Ttitanium dioxide (TiO 2 ) is favored for its non‐toxicity, low price and excellent photo/chemical stability [12] . However, pristine TiO 2 encounters the limits that contains wide band gap energy and fast electron‐hole pair recombination, so improving the separation efficiency of charge carriers and increasing the visible light absorption are the core issues in the extensive use of TiO 2 ‐based photocatalysts [12c,d,13] . These requirements can be achieved by doping with non‐metallic elements and constructing heterojunctions with other semiconductors [14] .…”