A novel chemical method has been developed for the fabrication of Ag nanoparticles-coated TiO₂ nanofiber composites. The method involves dispersion of TiO₂ nanofibers in silver salt solution under ultrasonication, followed by addition of sodium citrate as a reducing agent. The Ag-coated TiO₂ composites were characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron microscopy (XPS). Furthermore, the photocatalytic performance was evaluated by the photocatalytic degradation of methyl orange under UV-light irradiation. It was found that the heterogeneous Ag-TiO₂ composite showed a higher activity than the pure TiO₂ nanofiber; the enhanced activity can be attributed to the excellent distribution and interaction of Ag nanoparticles with the TiO₂ nanofiber support. A plausible mechanism for the formation of the Ag-coated TiO₂ composite and reasons for the enhancement of photocatalytic activity are also discussed.

Colored wide‐bandgap semiconductor oxides with abundant mid‐gap states have long been regarded as promising visible light responsive photocatalysts. However, their catalytic activities are hampered by charge recombination at deep level defects, which constitutes the critical challenge to practical applications of these oxide photocatalysts. To address the challenge, a strategy is proposed here that includes creating shallow‐level defects above the deep‐level defects and thermal activating the migration of trapped electrons out of the deep‐level defects via these shallow defects. A simple and scalable solution plasma processing (SPP) technique is developed to process the presynthesized yellow TiO₂ with numerous oxygen vacancies (Ov), which incorporates hydrogen dopants into the TiO₂ lattice and creates shallow‐level defects above deep level of Ov, meanwhile retaining the original visible absorption of the colored TiO₂. At elevated temperature, the SPP‐treated TiO₂ exhibits a 300 times higher conversion rate for CO₂ reduction under solar light irradiation and a 7.5 times higher removal rate of acetaldehyde under UV light irradiation, suggesting the effectiveness of the proposed strategy to enhance the photoactivity of colored wide‐bandgap oxides for energy and environmental applications.

Nanofibrous TiO2-core/conjugated polymer-sheath composite nanocables were synthesized by in-situ chemical oxidative polymerization of aniline with oxidant in the presence of TiO, nanofibers prepared through an electrospinning process. During the polymerization process, aniline molecules were adsorbed on the surface of TiO2. Upon the addition of oxidant, the polymerization of aniline takes place on the surface of the TiO2 nanofibers and polyaniline (PANI) is gradually deposited on their surface. The resulting TiO2-PANI nanocomposites have a coaxial nanocable structure. The morphological and structural properties of the composite nanocables were analyzed by using high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) and UV-visible spectroscopy (UV-vis), respectively. The HRTEM images proved that PANI (20 nm thickness) covered the surface of the TiO2 nanofibers. Also, the photocatalytic activity for the degradation of organic dyes on fibrous photocatalysts under UV-light was studied. The photocatalytic experiments showed that dye could be degraded more efficiently on the TiO2-PANI composite nanocables than on pure TiO2, due to the charge transfer from PANI to TiO2. The method for the synthesis of these unique structured composite nanocables is simple, rapid and reproducible. This facile method may be developed to produce multifunctional nanocomposites of various polymers with metal oxide fibers on a large scale for various technological applications such as sensors, solar cells, and catalysts.