Modeling The Influences Of Metallic Nanoparticles On The Solar Energy Absorption And Photocatalytic Properties Of TiO₂

Recent years have seen a renewed interest in the harvesting and conversion of solar energy.Metallic nanostructures have been extensively studied for their unique optical properties of localized surface plasmon effect.In this paper,we construct a model to study the influence of Ag or Au nanoparticles on the solar energy absorption and photocatalytic properties of semiconductor catalyst.Effects of specific nanoparticle coupling parameters,such as particle shape,size,doping period?metal-metal distance?and separation distance?metal-semiconductor distance?,on the properties of TiO₂ are studied in detail.The results can help the design of solar energy materials,in which metallic nanoparticles may play an important role.We show that the photocurrent improvement can be optimized by setting suitable geometric parameters.The energy absorption increases with silver nanoparticles,while it decreases with gold nanoparticles.In particular,the separation distance between metallic nanoparticles and TiO₂ should be around 6-8 nm,and the period of doping P should be around 360 nm.The silver cubes with edge length L =120nm show the best performance.A new class of silver nanostructures,concave nanocubes,are proposed to harvest UV-visible light for photocatalysis of semiconductors.Concave Ag nanocubes can concentrate the electric field in their vicinity and trigger "hot-spot" phenomenon at their edges and corners.This phenomenon can accelerates the formation of electron-hole pairs and induce enhanced photocatalytic effect of semiconductor bases.Concavity degree is a critical parameter of concave nanocubes for the solar energy absorption.The catalytic efficiency enhancement coefficient ?F of concave nanocubes with larger concavity degree?a=20°?is about 8%higher than that of Ag cubes.Therefore,the electric field intensity enhancement of TiO₂ doped with Ag concave nanocubes turns out to be comparable to that of Ag cubes.