(Invited) High-Throughput Local Electrochemistry Coupled with (in-situ) microscopy to Advance on the Fundamentals of Electrochemical Nucleation and Growth

Abstract

Electrochemical nucleation and growth (EN&G) are the cornerstone for many (nano)material growth routes and the main factor limiting battery durability. The in-depth experimental assessment of the process is very challenging due to the random nature of initiation events (nucleation), the heterogeneity of surfaces and the (very) fast kinetics across several length scales. For all that, our understanding of the mechanisms involved is inaccurate and incomplete [1].During the last years, we have developed an approach based on using carbon coated TEM grids as electrodes to combine ex-situ atomic-scale TEM characterization with electron tomography and macroscale electrochemical measurements [2,3]. This approach has brought valuable evidence of non-classical growth pathways such as growth mediated by nanocluster aggregation [3,4]. Yet, it does not capture the influence of the heterogeneous nature of the surface where EN&G proceeds, nor the dynamics before, during and after nucleation [5].In this contribution, we present our recent work in which we combine high-throughput local electrochemistry by Scanning Electrochemical Cell Microscopy (SECCM), with ex-situ and in-situ characterization, including electrochemical transmission electron microscopy (EC-TEM), to study the electrochemical nucleation and growth of metals on carbon surfaces [6,7].The spatially resolved electrochemical characterization enables a one-to-one correlation between the electrochemical data and the local surface properties, which can be evaluated by different surface analytical tools (SEM, AFM, ...) in identical locations to where the local electrochemical measurements have been performed. In addition, EC-TEM allows the study of the early-stage growth/dissolution dynamics of the metallic phase.The combination of both methods opens new opportunities for fully understanding the complex nature of EN&G phenomena. In the longer run, this can be exploited for the rational design (electrodeposition) of functional nanostructured materials considering the heterogeneous nature of the supports and the differences within nanomaterial ensembles.