The nucleation and growth mechanism is a well-known, but sometimes complicated process that describes metal electrodeposition.  Understanding the process is important for controlling metal electrodeposition, which is used for metal plating, electrocatalysis, sensing, nanostructure synthesis, and electronics.  There have been many recent fascinating studies where the nucleation and growth process has been studied at the nanoscale in-situ or even down to the single atom level with high resolution scanning probe or electron microscopy techniques.  In many of these studies the focus is on both the nucleation and growth, where the nucleation step is uncontrolled.  In our work, we focus on the growth step of metal electrodeposition by studying the electrochemical reduction of AuCl<sub>4</sub><sup>-</sup> onto pre-synthesized Au nanoparticles (NPs) ranging from 0.9 nm up to 50 nm in diameter attached to indium-tin-oxide-coated glass electrodes (glass/ITO).  Voltammetry indicates widely different electrodeposition growth kinetics depending on the size of the Au NPs.  Au NPs of 4 nm show much faster kinetics compared to 15 nm NPs, which is faster than 50 nm and unfunctionalized glass/ITO, while 0.9 nm and 1.6 nm NPs are slower than 4 nm NPs.  The electrodeposition kinetics are fastest for the 4 nm Au NPs among the sizes studied considering the same overall Au surface area, relatively low Au NP coverages, and overlapping diffusion layers for all Au NPs (linear diffusion).  The binding strength of ligand or surfactant stabilizers on the Au NP nucleation sites also plays an important role in the growth kinetics.  This work is not only important for a better understanding of metal electrodeposition but also useful in understanding metal NP synthesis using chemical reduction methods, especially those using the seed-mediated growth of pre-synthesized NP seeds.  Further, the different kinetics of growth on different-sized Au NPs is useful for selective deposition and enhancement in signal for Au oxidation in anodic stripping voltammetry (ASV).  This is useful for lowering the detection limit for NP detection and ASV-based sensing.

Size-Dependent Electrocatalytic Metal Growth of Metal Nanoparticles for Selective Signal Amplification in Electrochemical Sensing

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.