Electrodissolution Inhibition of Gold Nanorods with Oxoanions

Abstract

Metal nanoparticles experience varied chemical environments that can cause corrosion and dissolution in electronics, electrocatalysis, and sensing applications. Understanding oxidative dissolution is critical for plasmonic nanoparticles because their optical properties strongly depend on size and shape. We demonstrate that the addition of low relative concentrations of oxoanions to aqueous halide electrolyte solutions improves the morphological stability of plasmonic gold nanorods at anodic electrochemical potentials that otherwise induce complete oxidative electrodissolution. Single particle hyperspectral dark-field imaging and correlated scanning electron microscopy show that oxoanions alter the electrodissolution onset potential, electrodissolution pathway, and nanoparticle reaction heterogeneity, as compared to chloride-only electrolyte solutions. We identify five mechanistic contributors to the corrosion inhibition capabilities of oxoanions in the presence of chloride ions, with the aim of expanding the range of electrochemical sensing and catalysis applications for plasmonic metal nanoparticles. Of the contributors investigated, the pH, adsorption potential, and ionicity of the oxoanion are found to be the most influential factors, supporting the superior corrosion inhibition observed with bicarbonate and phosphate.

Toward Real-Time Monitoring and Control of Single Nanoparticle Properties with a Microbubble Resonator Spectrometer

“…47 Additionally, dissolution of AuNRs via substrate voltage tuning has been monitored using dark-field hyperspectral imaging. 48,54 Perhaps the most commonly reported reagent for etching single AuNRs in recent years is iron(III) chloride, starting with bulk studies in 2009. 82 Since then, FeCl 3 etching of single AuNRs has been reported using dark-field monitoring, sometimes utilizing Le Chatlier’s principle to drive the reaction.…”

“…A variety of optical methods exist for probing nonluminescent single nanoparticles and molecules via photothermal, 35−38 scattering, 39−41 and other techniques. 42−45 Observation of the chemical etching of single AuNRs has recently been accomplished with one-photon luminescence, 46,47 dark-field scattering, 48−54 and liquid transmission electron microscopy (TEM). 55 However, a highly sensitive absorption technique for monitoring such chemical dynamics is needed to compliment these methods and would be extremely valuable for accessing targets that are not luminescent or are too small for scattering experiments.…”

Plasmon Energy Transfer in Hybrid Nanoantennas

“…Transparent electrochemical cells were prepared according to our literature procedure. 57 Insulated platinum wire (A-M Systems, 0.002 mm 2 geometric area on the exposed end) was used for the quasi-reference electrodes. Nylon filters (0.45 μM, Whatman) were used to filter the electrolyte solution before filling the cell chamber.…”

“…To span a larger range of E res , two separate batches of chemically prepared AuNRs with similar widths but different aspect ratios were used in the experiments. The ensemble characterization of the AuNRs used are provided elsewhere. , One batch had an average aspect ratio of 2.5 ± 0.3 and covered an E res range of 1.33–1.66 eV (Figure S1 in Flatebo et al ), and the other had aspect ratio values of 2.0 ± 0.3 and an E res range of 1.55–1.95 eV (Figure S16 in Yorulmaz et al ) . The average dimensions quoted here were obtained by direct SEM analysis and only include sample data from the single particles used in our experiments and differ slightly (within the error range of the measurements) from the transmission electron microscopy (TEM) derived values in the original publications.…”

Electrochemically driven dynamic plasmonics

“…The behavior can be observed in nanoparticles, nanorods, nanodimers, and Au lattices. [91][92][93][94] The rate of electrodissolution can be adjusted (accelerated by laser excitations with hot holes, 95 inhibited with low concentrations of oxoanions 96 ). Under potential deposition (UPD) 97 technologies can also be applied for metal dissolution of Au dimer structures.…”