Plasmon-Enhanced Photocatalytic Activity of Cadmium Sulfide Nanoparticle Immobilized on Silica-Coated Gold Particles

Nanocomposite photocatalysts of CdS nanoparticles immobilized on Au core-SiO2 shell particles, in which the SiO2 layer acts as an insulator layer to prevent direct electron transfer from photoexcited CdS to Au particles, were prepared. The photocatalytic activity of CdS particles for H-2 evolution was greatly dependent on the distance between CdS and Au particles, due to the locally enhanced electric field produced by photoexcitation of the localized surface plasmon resonance (LSPR) peak of Au particles. Increase in Au core size enlarged the optimal distance between Au and CdS for the enhancement of photocatalysis. This behavior was theoretically reproduced by solving a self-consistent equation system, in which the range of energy dissipation became wider for larger diameter of the Au sphere, and then the balance with the enhancement of photoexcitation of CdS particles by the LSPR-induced electric field was changed.