Investigation into the effect of plasmon boosting of TiO2 for photocatalytic destruction of organic molecules

To investigate the effect of gold nanoparticle surface plasmon resonance (SPR) on titanium dioxide (TiO2) photocatalysis for the breakdown of organic molecules in different settings. Experimental: Four types of nanoparticle were fabricated for this investigation; Silica-dye colloid (A), gold core silica-dye shell (B), silica-dye core coated in gold seeds (C), silica-dye core coated in a gold nanoshell (C). The dye used in this investigation was Rhodamine B isothiocyanate (RhB). The particles were used to examine their fluorescent boosting effects and therefore their potential at boosting photocatalytic activity. The particles were tested for fluorescence using the same amount of dye molecules and also underwent photocatalytic exposure with TiO2 films produced by magnetron sputtering. Results: Gold core silica-dye shell nanoparticles (B) gave almost five-fold enhancement. The silica-dye core coated in gold seeds (C) also boosted fluorescence enhancement by a factor of almost 200, a much greater increase compared to the gold core particle (B). TiO2 enhances the photo-bleaching of RhB through a loss of fluorescence on its own, and a further doubling the rate when exposed to gold nanoparticles. When encapsulated in silica a protective barrier is formed preventing normal breakdown of dye, however, using a gold core or gold seeds on the nanoparticle surface overcame this barrier to degrade the dye by a small amount.