Comparative study of the physicochemical and photocatalytic properties of water-soluble polymer-capped TiO2 nanoparticles.

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.