Nucleation and Growth Kinetics at Electrochemical Interfaces: Insights from Single-particle Studies via Scanning Electrochemical Cell Microscopy (SECCM)

Electrochemical studies of nucleation and growth of nanoparticles (NPs) play a critical role in a variety of systems. Leveraging a firm understanding of the underlying kinetics to exerting control over the nucleation and growth of NPs enables their properties to be tailored for different electrochemical applications including catalysis, energy conversion, and sensing. Prior work from our group has demonstrated that scanning electrochemical cell microscopy (SECCM) can serve as a powerful, instantly reconfigurable tool for fabricating well-ordered NP arrays. In this approach, electrolyte-filled pipets are utilized to drive the electrodeposition of individual NPs of controlled size locally on a conducting substrate with sub-µm resolution. Here, we present studies which explore the nucleation and growth kinetics of NPs fabricated on pyrolyzed carbon, Indium tin oxide (ITO) and highly ordered pyrolytic graphite (HOPG) substrates via SECCM. By analyzing the nucleation and growth data of single particles synthesized at a series of different applied potentials through distinct kinetic models, we demonstrate that it is possible to exert spatial control over nucleation and growth kinetics of 100’s of NPs within different interfaces. We analyze distributions in nucleation times to quantify kinetic rates on different substrates and differentiating kinetic rates at basal planes vs. site defects in heterogeneous interfaces. The results shown here demonstrate a powerful new approach to the analysis of single particles for different electrochemical applications.