TiO(2) bilayer films with a normal surface (Ns-TiO(2)), surface defects (Sd-TiO(2)), and interface defects (Id-TiO(2)) were successfully prepared by a combination of cold plasma treatment (CPT) and sol-gel dip-coating technology. The photodegradation of rhodamine B (RhB) over these as-prepared TiO(2) films was investigated via UV-vis irradiation. Results indicate that the three kinds of films exhibit very different photodegradation processes for RhB. A mainly N-deethylation reaction over the Ns-TiO(2) films, whereas an efficient degradation (cycloreversion) of RhB occurs over the Sd-TiO(2) films. In the RhB/Id-TiO(2) system, however, efficient N-deethylation concomitant with the highly efficient cycloreversion of RhB is observed. The efficiency of the complete mineralization of RhB dye follows the order of Id-TiO(2) > Sd-TiO(2) > Ns-TiO(2). It is proposed that the defect sites at the surface or the interface of TiO(2) films promote the separation of photogenerated electron-holes, leading to a higher photoactivity of defective TiO(2) films. Moreover, the higher stability over Id-TiO(2) as compared to Sd-TiO(2) indicates that the interface defect sites in TiO(2) could be applied in environmental photocatalysis.

A novel organic semiconductor photocatalyst mimicking natural light-harvesting antenna complexes in photosynthetic organisms, a disulfide (-S-S-) bridged C 3 N 3 S 3 polymer, was designed and developed to generate hydrogen from water under visible light irradiation. The artificial conjugated polymer shows high H 2 -producing activity from the half-reaction of water splitting without the aid of a sacrificial electron donor. The H 2 -producing efficiency and photo-stability of the catalyst could be improved greatly using Ru and single-wall carbon nanotubes as cocatalysts or by adding a sacrificial donor. The results represent a potential and prospective application of the C 3 N 3 S 3 polymer in solar energy conversion and offer significant guidance to develop more stable and efficient photocatalytic systems based on organic semiconductors.

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