Plasmon enhanced electrochemical dissolution of gold nanorods

Abstract

Plasmonic nanoparticles have been proposed as active and selective electrocatalysts due to local heating and hot carrier generation through local surface plasmon resonance (LSPR) excitation. The electrochem. stability of gold nanoparticles based on size and crystal structure has been extensively studied in halide solns. However, under light excitation in addn. to electrochem. potential the same plasmonic effects that enhance catalytic activity may make the nanoparticles less stable and dissolve at lower electrochem. potentials. In this work we study single plasmonic gold nanorods (AuNRs) at various electrochem. potentials with and without white light laser (WLL) excitation in an aq. chloride electrolyte soln. As electrochem. potential was increased, AuNR dissoln. was tracked by changes in the LSPR scattering spectra and confirmed with correlated SEM. WLL excitation produced heterogeneous dissoln., some AuNRs dissolved at much lower potential under WLL excitation and at a greater rate. Wavelength dependent measurements showed that longitudinal plasmon mode excitation was primarily responsible for the laser mediated AuNR dissoln. enhancements. As local heating effects were minimal at the laser power densities used in these expts., the plasmon enhanced dissoln. is best explained by a hot hole driven dissoln. mechanism.