TiO₂ photocatalysis for gas-phase applications is a promising technology but can be limited by the uniform delivery of photons to the photocatalyst surface. Optical fibres, as a possible solution to this issue, have been under investigation for over a decade. Cylindrical optical fibres act both as a photocatalyst support and as a light guide for directing photons to the photocatalyst surface. Improved light utilisation has been reported to occur in some instances [1,2].

Light propagation in cylindrical optical fibres suffers from exponential decay along the fibre axis. This decay limits the application of optical fibres in air purification systems. Strong light guidance in holey optical fibres may provide a solution to the exponential decay problem. Holey optical fibres comprise a core through which a number of air channels run along the axis and hold potential for gas phase applications. The small channels increase the available irradiated surface area and reduce mass transfer limitations.

In this work, a 6mm holey optical fibre with twenty 0.4mm-hexagonal channels was employed as a reactor for the gas-phase photocatalytic oxidation of ethylene. TiO₂ particles were coated on the channel wall. The TiO₂-coatings were characterised by secondary electron microscopy (SEM) and Focused-Ion Beam (FIB) spectroscopy. The effects of ethylene concentration, incident photons and gas flow rate have been studied.

References
1. Peill, N. J.; Hoffmann, M. R. Environmental Science and Technology 1995, 29, 2974.
2. Lin, H.; Valsaraj, K. T. Journal of Applied Electrochemistry 2005, 35, 699