Field Effects in Plasmonic Photocatalyst by Precise SiO₂ Thickness Control Using Atomic Layer Deposition

We report on TiO 2 thin films with superior photocatalytic efficiency due to an increase in its exciton carrier generation induced by the plasmonic field of the underlying silver nanoparticles. TiO 2 thin films are deposited on supported silver nanoparticles and are separated from each other by a fine-tunable thickness of SiO 2 interlayer. The TiO 2 (15 nm)/SiO 2 /Ag nanoparticle architectures with systematic variation of SiO 2 interlayer thickness of 2, 5, 10, and 20 nm show systematic increase in photocatalytic efficiency with decrease in the SiO 2 thickness. The efficiency enhancement is shown to be caused by plasmonically enhanced carrier generation, which was confirmed through photocurrent measurements and Raman spectroscopy. With a 2 nm SiO 2 interlayer that exhibited the best photocatalytic performance, a 3 times increase in photocurrent density, and a 200 times increase in Raman signal intensity of TiO 2 is found. Atomic layer deposition was employed to achieve precise film thickness control of SiO 2 and TiO 2 layers.