Abstract

Plasmonic nanoparticles in contact with semiconductor exhibit plasmon-induced charge separation (PICS) under visible and near infrared light.¹ PICS is based on carrier transfer from plasmonic nanoparticles to semiconductor^1,2 due to external photoelectric effect, hot carrier injection, or interfacial electron transition. The most typical system exhibiting PICS consists of Au nanoparticle and TiO₂. We observed electron injection from a single Au nanoplate to Nb-doped TiO₂ in contact, by means of Kelvin probe force microscopy (KFM).² Information about the cathodic and anodic potentials are important for designing PICS-based devices and materials. At open circuit, the cathodic potential of the Au-TiO₂ system is around the flat-band potential E_fb of TiO₂. However, direct measurement of the anodic potential is difficult. We therefore measured it indirectly on the basis of chemical reactions such as ligand-assisted oxidative dissolution and surface hydroxylation of Au nanoparticles and concluded that the anodic potential is around E_fb + hν (Fig. 1).³

© 2016 Japan Society of Applied Physics, Optical Society of America