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 electrochemical stability of gold nanoparticles based on size and crystal structure has been extensively studied in halide solutions. However, under light excitation in addition to electrochemical potential the same plasmonic effects that enhance catalytic activity may make the nanoparticles less stable and dissolve at lower electrochemical potentials. In this work we study single plasmonic gold nanorods (AuNRs) at various electrochemical potentials with and without white light laser (WLL) excitation in an aqueous chloride electrolyte solution. As electrochemical potential was increased, AuNR dissolution was tracked by changes in the LSPR scattering spectra and confirmed with correlated SEM. WLL excitation produced heterogeneous dissolution, 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 dissolution enhancements. As local heating effects were minimal at the laser power densities used in these experiments, the plasmon enhanced dissolution is best explained by a hot hole driven dissolution mechanism.

Plasmon enhanced electrochemical dissolution of gold nanorods

255th National Meeting (2018)

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