Accelerated site-selective photooxidation on Au nanoparticles via electrochemically-assisted plasmonic hole ejection

In order to induce electrochemical reactions by localized surface plasmon resonance (LSPR), semiconductors have been employed as electron or hole acceptors for plasmon-induced charge separation (PICS) in most cases. Here we replaced a semiconductor with a potential-controlled transparent electrode, and achieved accelerated photooxidation reactions at selected local sites on plasmonic metal nanoparticles. We demonstrate site-selective PbO₂ deposition at the tips and sides of Au nanorods and PbO₂ deposition and Au dissolution at the top and bottom of Au nanocubes, through the selective excitation of different LSPR modes. Energetic electron-hole pairs are generated at a plasmonic resonance site, and oxidation reactions are driven by hole ejection at the site. The complementary electrons are removed via the positively biased electrode, and consumed at a counter electrode by reduction reactions. In the case of the PbO₂ deposition, formation of PbO₂ nuclei is triggered by the hole ejection, and PbO₂ is grown further in an electrochemical manner at an improved rate.