Enhancement of light absorption of cadmium sulfide nanoparticle at specific wave band by plasmon resonance shifts

Cadmium sulfide (CdS) is a common photocatalyst used for photocatalytic processes. Only those photons with energy above or equal to 2.4 eV (corresponding to band gap of CdS) are absorbed and contribute to the photocatalytic behavior. In this paper, the concept of multilayer nanoshell plasmonic photocatalyst is introduced into photocatalysis for hydrogen production based on the water-splitting technique. The optical properties of novel multilayer nanoshells consisting of Ag, SiO₂ and CdS are investigated by means of plasmonics theory and plasmon hybridization model. The optical properties with structural parameters of Ag/SiO₂/CdS composite nanoparticles are studied by discrete dipole approximation (DDA) method. The results show that the absorption performance of this novel multilayer nanoshell is remarkably improved when localized surface plasmon resonance (LSPR) is excited on the surface of Ag nanoparticle exposed under UVvis illumination. By adjusting the intermediate layer thickness, the resonance wavelength can be conveniently tuned to desired wavelength range. For a thinner intermediate layer, the resonance wavelength is red shifted. Parameter optimization gives rise to the optimal structure of outstanding absorption performance.