Comparative study of the physicochemical and photocatalytic properties of water-soluble polymer-capped TiO 2 nanoparticles

Abstract

TiO₂ shows great potential as ideal and powerful photocatalyst to degrade and eliminate harmful organic pollutants from waste water. It is desirable to prepare anatase TiO₂ with good aqueous solubility and photocatalytic activity for water decontamination. In this paper, water-soluble TiO₂ nanoparticles were successfully prepared using polytetramethylene ether glycol (PTMG), poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG) as stabilizers. The anatase phase of TiO₂ was well controlled by introduction of HCl in the reaction system. The results showed that all the polymer-capped TiO₂ were well dissolved in water and their aqueous solutions could maintain stable for more than 2 months. The photocatalytic activities of polymer-capped TiO₂ were evaluated by monitoring the degradation of Rhodamine B (RhB) with Degussa P25 as a control. The results showed that all the polymer-capped TiO₂ presented better photocatalytic activity than that of Degussa P25. PTMG capped TiO₂ exhibited the longest average lifetime of charge carriers, indicating the lowest charge recombination rate. Thus, PTMG capped TiO₂ presented the best photocatalytic activity. In summary, PTMG, PEG, and PPG can be used as stabilizers to prepare water-soluble TiO₂. PTMG is an ideal stabilizer for the synthesis of water-soluble TiO₂ with good photocatalytic activity.