Metal layers with subwavelength texturing for broadband enhancement of photocatalytic processes in microreactors

Abstract

In this paper we joined plasmonics and microreactors for photocatalytic optofluidic devices. To this purpose we consider the use of subwavelength texturing of plasmonic films applied to microreactor channel bottom to ensure SPP localization and field enhancement. The small volume of the microchannel is ideal for the enhancement of photocatalytic processes using localized evanescent fields. A great advantage of our approach is that it is highly compatible with the standard chemical bulk micromachining techniques which are commonly used in fabrication of the microreactors i.e. standard photolithography can be used to define microchannels, and radiofrequent sputtering to deposit a gold film as a plasmonic material over the roughened surface. Subwavelength surface texturing can be obtained by varying etching techniques and parameters and the microreactor building materials. We show using ab initio FEM modeling that the stochastic surface profile ensures broadband coupling of visible light as well as enables us to merge plasmonic sensors and microreactors into a single device.