Fabrication of fractal structured soot templated titania-silver nano-surfaces for photocatalysis and SERS sensing

Abstract

A novel approach of candle soot templated TiO2/Ag nanostructures to fabricate highly active photocatalyst and self-cleaning Surface-Enhanced Raman Scattering (SERS) substrates is demonstrated. A three-stage synthetic approach involves the replication of the fractal structure of candle soot in forming a high surface area porous TiO2 nanostructure using chemical vapour deposition and subsequent electroless deposition of silver nanoparticles on the high surface area fractal network that resulted in the formation of TiO2/Ag nanostructures. The unique morphology of TiO2/Ag renders these materials to exhibit photocatalytic and SERS activity. These surfaces showed an enhanced photocatalytic effect due to the Schottky junction which increases the recombination time of the charge carriers. The size and the coverage of the silver nanoparticles were optimized to obtain high conversion towards photocatalytic degradation of a model dye molecule such as Rhodamine B (RhB). The same substrate was also shown to enhance the Raman scattering spectra of RhB. The SERS activity of the substrate can be regenerated by photocatalytic cleaning the substrates. Overall, this present work demonstrated that fractal structured TiO2/Ag materials can be synthesized using fractal soot structures and this multi-functional material offers good potential in those applications, where photo-catalysis, SERS sensing, and self-cleaning sensing multifunctionality are required.