Ag@Cu2O Core-Shell Nanoparticles as Visible-Light Plasmonic Photocatalysts

Compared to pristine Cu2O nanoparticles (NPs), Ag@Cu2O core-shell NPs exhibit photocatalytic activity over an extended wavelength range because of the presence of localized surface plasmon resonance (LSPR) in the Ag core. The photocatalysis action spectra and transient absorption measurements show that the plasmonic energy is transferred from the metal to the semiconductor via plasmon-induced resonant energy transfer (PIRET) and direct electron transfer (DET) simultaneously, generating electron–hole pairs in the semiconductor. The LSPR band of Ag@Cu2O core-shell NPs shows a red-shift with an increase in the Cu2O shell thickness, extending the light absorption of Ag@Cu2O heterostructures to longer wavelengths. As a result, the photocatalytic activity of the Ag@Cu2O core-shell NPs is varied by modulation of the shell thickness on the nanometer scale. This work has demonstrated that the Ag@Cu2O core-shell heterostructure is an efficient visible-light plasmonic photocatalyst, which allows for tunable light absorption over the entire visible-light region by tailoring the shell thickness.