Diversity Matters: Influence of Surface Heterogeneities in the Electrochemical Nucleation and Dissolution of Au Nanoparticles

Abstract

The investigation of the nucleation and dissolution of gold nanoparticles on a glassy carbon substrate with Scanning Electrochemical Cell Microscopy (SECCM) combined with in-situ electrochemical TEM (EC-TEM) revealed the subtle influence of the local properties of the substrate on the electrochemical processes. Conducting hundreds of locally-resolved voltammograms at the micro-scale resulted in the observation of a diversity of responses for nucleation, allowing to address experimentally the statistical nature of the nucleation and growth process. Moreover, during the electrochemical dissolution of previously electrodeposited nanoparticles (NPs), the confinement conditions of the SECCM-cell allowed the resolution of a multitude of events characterized as current spikes. Such current events are not observable in the macro-scale since the electrochemical response over the large electrode area is the convolution of the activity all over the electrode surface. The EC-TEM experiments demonstrated that such current spikes were generated by the dissolution of individual NPs distributed over a time range. Combining SECCM and EC-TEM unmasked information previously not seen from the electrochemical nucleation, growth, and dissolution of supported metal nanoparticles [1]. This approach could accelerate the discovery of novel functional electrode materials by facilitating the rational design of protocols for electrodeposition of nanostructured materials and the evaluation of their stability under electrochemical conditions. The possibility to consider the heterogeneous nature of the supports and the differences within nanomaterial ensembles opens the opportunity to consider the diversity of electrochemical parameters as descriptors to understand and describe the relationships between activity, stability, and structure.[1] M. Bernal, D. Torres, S. Semsari, M. Čeh, K. Žužek Rožman, S. Šturm, J. Ustarroz, Diversity matters: Influence of surface heterogeneities in the electrochemical nucleation and dissolution of Au nanoparticles, under revision