(Invited) High-Throughput Nanoscale Resolved Electrochemistry to Study Electrochemical Nucleation, Growth and Dissolution
Authors: Ustarroz Jon , Bernal Lopez Miguel , Torres Daniel , Hussain Sajid , Bertolucci Coelho Leonardo 
Published: July 2022

Electrochemical nucleation and growth (EN&G) is the cornerstone for many (nano)material growth routes and the main factor limiting battery durability. At the same time electrochemical dissolution (ED) is the main cause of material degradation in exposed environments (corrosion) or energy conversion and storage devices. The in-depth experimental assessment of both processes is very challenging. The reasons are the random nature of initiation events (nucleation), the heterogeneity of surfaces and the (very) fast kinetics of these processes across several length scales. For all that, our current 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. 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 [4,5].
In this contribution, we present our recent work in which we combine high-throughput nanoscale resolved electrochemistry by Scanning Electrochemical Cell Microscopy (SECCM), with ex-situ and in-situ high resolution characterization, including electrochemical transmission electron microscopy (EC-TEM), to study the electrochemical nucleation, growth, and dissolution of metal (Cu, Au, Ag and Pt) nanoparticles (NPs) [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.
Moreover, the confinement of the electrochemical cell to the SECCM meniscus enables us to resolve a diversity of events during the electrochemical dissolution of electrodeposited NPs. EC-TEM experiments advocate that the nature of these events corresponds to the dissolution of individual NPs spanning a wide range of time [6].
The combination of SECCM and EC-TEM opens up new opportunities for the rational design of functional nanostructured materials by electrodeposition, and for the evaluation of their durability under electrochemical polarization. The ability to study these taking into account the heterogeneous nature of the supports and the differences within nanomaterial ensembles is essential for applications in electrochemical conversion and storage.
References:
[1] Ustarroz, J. Current Opinion in Electrochemistry. 19 (2020) 144–152.
[2] Ustarroz, J et al. Journal of the American Chemical Society (2013), 135, 11550–11561.
[3] Ustarroz, J et al. The Journal of Physical Chemistry C (2012), 116, 2322–2329.
[4] Hussein H. E. M. et al., ACS Nano. 12, 7388–7396 (2018).
[5] Harniman R. L. et al., Nat. Commun. 8, 971 (2017).
[6] Bernal, M. et al. In revision (2022).

[7] Torres, D. et al. To be submitted (2022).