Theoretical calculations for localized surface plasmon resonance effects of Cu/TiO2 nanosphere: Generation, modulation, and application in photocatalysis

The localized surface plasmon resonance (LSPR) is considered as one of the effective strategies to broaden the spectral absorption range and improve quantum conversion efficiency or photocatalyst. Because of low-cost and LSPR absorption peaks in the visible-light region, Cu-based plasmonic photocatalysts have attracted concern in recent years. However, the mechanisms of generation, modulation, and application of LSPR effects of Cu nanoparticles are still insufficient. To this regard, by using finite-difference time-domain simulations and density functional theory calculations, the intrinsic mechanism of LSPR in the system of Cu nanosphere loaded onto TiO2 nanosphere has been systematically analyzed. When Cu nanosphere is gradually sinking into TiO2 nanosphere to form core-shell configuration, the LSPR absorption peaks is gradually red-shifting and separated from the interband region of metallic Cu nanosphere. The interfacial electronic states are the root of enhancement and red-shifting of LSPR absorption peaks in Cu/TiO2 nanospheres. What's more, the LSPR effects of different Cu/TiO2 nanosphere configurations are highly susceptible to the dielectric media with high refractive index, the direction of incidence light, and environmental media. The embedding configuration of Cu/TiO2 nanospheres is predicted to present outstanding photocatalytic performance, owing to less affected by the incident direction of light, effectively excited LSPR wavelength and local electric field, and more reaction sites for photo-redox reaction. The findings in the present work provide a convenient and efficient approach to screen plasmonic photocatalysts for efficient solar energy conversion.