Enhancement of Hot Electron Generation in Colloidal Plasmonic Nanocrystals by Adsorption of Pt Clusters

摘要

Surface scattering of electrons is used to be recognized as a detrimental damping process of the plasmonic oscillation, whereas such electron-surface scattering generates hot electrons (HEs) inside the metal nanocrystals, being of great significance in practical applications, i.e., photodetection or photocatalytic reactions. However, utilizing surface scattering in colloidal plasmonic nanocrystals in realistic catalytic reactions remains challenging. This work presents a systematic study on the HE rates of colloidal Au nanocrystals, including nanospheres, nanocubes, and nanorods, and their enhancement from the adsorption of Pt clusters. Au nanocubes exhibit the highest single particle-averaged incident photon-to-electron conversion efficiency among the three types of the nanocrystals. The Au nanocrystals are further adsorbed with Pt clusters, and the highest photocurrent enhancement by nearly one order of magnitude is observed. To explain the experimental observations, the contribution of the Pt adsorption to the plasmon damping is characterized by single-particle dark-field spectroscopy, and the HE rates are calculated by employing the finite-element method. The overall significant enhancement of the photocurrent due to the Pt adsorption is finally explained by both electromagnetic and catalytic effects of the Pt clusters.