Surface Bridge Hydroxyl-Mediated Promotion of Reactive Oxygen Species in Different Particle Size TiO₂ Suspensions

Abstract

Reactive oxygen species (ROS) play an essential role in TiO 2 photocatalysis. They arise from the transfer of lightinitiated carriers to the TiO 2 surface and react with oxygen or water, in which the TiO 2 surface is crucial. However, how the TiO 2 surface affects ROS production is unclear. Herein, dynamic generation of ROS in suspensions of TiO 2 of different particle sizes was investigated under ultraviolet-light irradiation. It is surprising to find that more ROS were produced more quickly for 100−140 nm TiO 2 than for 20−60 nm TiO 2 . Further research suggested that ROS production was intrinsically correlated with the surface bridging hydroxyls per unit area. More bridging hydroxyls induced lower IEP and more negative charges on the TiO 2 surface, which favored the transfer of photogenerated carriers, resulting in the promotion of ROS and photocatalytic activity. This provided insight into designing high-efficiency photocatalysts to solve the problem of small particle sizes causing loss and blockage in wastewater treatment.

Chitosan and nano-TiO2 coating improves the flame retardancy of dyed and undyed denim fabrics by increasing the charring

“…Nanoparticles are powerful addition agents to improve the thermal properties and morphology of char, due to their strong interaction with polymers and high decomposition temperature. 57,58 It has been demonstrated in previous studies that nano-TiO 2 provides thermal stability as an effective inorganic barrier. 18,59 In this study, we observed that nano-TiO 2 increased the thermal resistance of the blue dyed denim fabric and reduced the mass loss.…”

Rapid evaluation of oxygen vacancies-enhanced photogeneration of the superoxide radical in nano-TiO2 suspensions

“…S1 †). 28,37 Two quartz beakers (100 mL) were used for nano-TiO 2 (0.1 mg mL À1 ) and luminol (50 mM). The two containers were connected separately to the peristaltic pumps through pump tubing (i.d.…”

“…37 The concentrations of O 2 c À and cOH were quantied according to our previous report. 28,38 Photocatalytic degradation of Rhodamine B…”

“…1,14,[20][21][22][23]25,26 The photocatalytic process began with the generation of electron-hole pairs, and photoelectrons were captured by molecular oxygen to produce superoxide free radicals, avoiding the accumulation of electronhole composites and negative charges on the surface. 1,[20][21][22][26][27][28] Thus, the nano-TiO 2 surface oxygen defect sites were the center of photocatalytic activity. However, oxygen vacancies are elusive species, and are also oen highly diluted and therefore difficult to detect.…”

Influence of Multidimensional Graphene Oxide (GO) Sheets on Anti-Biofouling and Desalination Performance of Thin-Film Composite Membranes: Effects of GO Lateral Sizes and Oxidation Degree

“…The GO1 has the highest C/O ratio as compared with GO2 and GO3 (Table 2), and thus the lowest oxygenated group density, but GO1 presents only hydroxyl groups on its surface. It is known that hydroxyl groups on the material surface favor ROS generation [84]. Hence, the efficient bactericidal effect observed by the PA+GO1-PS membrane could be attributed to the presence of a high amount of this functional group (45.7%) available on the GO1 surface.…”