Wenxing Chen

Photocatalytic Activity of Heterostructures Based on TiO2 and Halloysite Nanotubes

A one-step solvothermal method was used to prepare TiO(2)/halloysite composites. TiO(2) nanoparticles were deposited on the platform of the halloysite nanotubes (HNTs). XRD, FT-IR, FE-SEM, and TEM were applied to investigate the structures and morphologies of the resultant samples. The as-prepared TiO(2)/HNTs photocatalyst exhibits pH sensibility on the degradation of methanol and a higher photocatalytic activity on the degradation of acetic acid. The combination of the photocatalytic property of TiO(2) and the unique structure of halloysite endowed this material with a bright perspective in degradation of organic pollutant.

Phase-selectivity photocatalysis: a new approach in organic pollutants’ photodecomposition by nanovoid core(TiO2)/shell(SiO2) nanoparticles

Core(TiO(2))/shell(SiO(2)) nanoparticles, with a void layer between the TiO(2) core and the silica layer, act as phase-selectivity photocatalysts for the photodecomposition of organic pollutants (gas phase) without any damage to their organic supports (solid phase).

Chemical morphology freezing: chemical protection of the physical morphology of high photoactivity anatase TiO2 nanotubes

In this paper, an unavoidable thermodynamic behavior of nanomaterials is prevented by using a simple chemical morphology freezing method. Titanate nanotubes (no photoactivity) are filled with LaMer-model carbon and then coated with a silica sheath. This chemical filling and coating process ‘isolates’ micro-thermal deformation from the system, and consequently prevents the destruction of the tubular morphology during the calcination process. After calcination, novel high photoactivity TiO2nanotubes are obtained with perfect open-ended tubular morphology and fine anatase phase. The sample shows the highest photoactivity of all the samples, which is 2 times higher than that of TiO2nanorods, and is 4 times higher than TiO2nanoparticles (P-25).

Gas-supported high-photoactivity TiO 2 nanotubes

By changing hydrothermal condition and post-heat-treatment temperature, silica-coated TiO2 nanotubes are obtained successfully. The effects of gas-supported process on tubular morphology, crystallinity, and photocatalytic activity are discussed. It is found that the sample prepared at hydrothermal treatment (180°C/9 h) and calcination (650°C/2 h) shows perfect open-ended tubular morphology and increased crystallinity. The photoactivity of the sample is proved to be 5 times higher than that of TiO2 nanoparticles.

Wet photochemical filling: a new low-diameter tube-filling method based on differentiated nanotube surfaces

In this work, by using a simple chemical morphology freezing method novel low-diameter tubular nanocomposites (TiO2–NTs@SiO2) with differentiated surfaces are prepared, in which the TiO2 layer acts as a photoactive inner surface and the SiO2 layer acts as an insulating outer surface. Because of the photoactivity of TiO2, under UV light irradiation, only the inner TiO2 surface can photoreduce a H2PtCl6 precursor solution to Pt nanoparticles on its surface. As a result, Pt nanoparticles are highly selectively filled in the tube inner channel after this wet photochemical filling process. Due to the high dispersity of Pt nanoparticles in the channel, the method can improve catalytic activity efficiently by increasing the ultimate effective Pt load. In photocatalytic H2-production experiments, nanotubes filled with 6 wt% Pt show the highest photoactivity of all the samples; this activity is twice that obtained with TiO2 nanoparticles loaded with 0.6 wt% Pt.