Photocatalytic Comparison of TiO2 Nanoparticles and Electrospun TiO2 Nanofibers: Effects of Mesoporosity and Interparticle Charge Transfer

Abstract

The development of a high-efficiency TiO 2 photocatalyst is of great importance to a variety of solar light conversion and application fields; the desired high efficiency can be achieved by employing well-controlled TiO 2 nanoarchitectures. In this study, we have successfully synthesized well-ordered and aligned high surface area mesoporous TiO 2 nanofibers (TiO 2 -NF) by electrospinning of TiO 2 powder dispersed in viscous polymer solution and subsequent calcination. For comparison, TiO 2 nanoparticles (TiO 2 -NP) are also prepared from calcination of the same TiO 2 powder. The TiO 2 -NF of ca. 500 nm in diameter and a few micrometers in length consist of compactly and densely packed spherical nanoparticles of ca. 20 nm in size and have mesopores of 3−4 nm in radius. Photocatalytic comparison between TiO 2 -NF and TiO 2 -NP indicated that the former had far higher photocatalytic activities in photocurrent generation by a factor of 3 and higher hydrogen production by a factor of 7. The photocatalytic superiority of TiO 2 -NF is attributed to effects of mesoporosity and nanoparticle alignment, which could cause efficient charge separation through interparticle charge transfer along the nanofiber framework. Finally, various surface characterization experiments were conducted and included to understand the photocatalytic behaviors of TiO 2 -NF and TiO 2 -NP.