(698e) Novel TiO2/ZnO/Bi2O3 Composite Nanofibers for Air Purification - Optimization, Kinetic Modeling and Mechanisms

Semiconductor heterojunction structures can effectively enhance the separation efficiency of photogenerated electron/hole pairs and the subsequent photocatalytic performance. Novel TiO₂/ZnO/Bi₂O₃ composite nanofibers, synthesized by a simple sol-gel assisted electrospinning method, exhibited much higher photocatalytic activity for the oxidation of nitrogen monoxide (NO) under simulated solar irradiation than commercial TiO₂ nanoparticles. These composite nanofibers have increased absorption in both UV and visible range when compared with TiO₂ nanoparticles. The enhanced photocatalytic activity of TiO₂/ZnO/Bi₂O₃ is attributed to the difference in the energy band positions of anatase, rutile, zincite and bismuth oxide, resulting in both lower band-gap energy and reduced recombination rate of photogenerated electron/hole pairs. Moreover, the photocatalytic performances are more stable for TZB nanofibers than that of TiO₂ nanoparticles, which are easily deactivated. In addition, a new kinetic model, taken into account of flow retention time and physical-chemical kinetics, is used to shed light on the behavior of the photocatalytic reaction. Faster kinetics (resulting in higher reactor throughput) and higher conversion efficiency of NO may be realized by optimizing the bismuth concentration in the composite nanofibers. The degradation pathway of o-xylene by TZB has also been investigated.

Keywords:

TiO₂/ZnO/Bi₂O₃ composite nanofibers, solar-light driven photocatalyst, kinetic model, o-xylene degradation