Electrochemical nucleation and growth (EN&G) are the cornerstone for many (nano)material growth routes and the main factor limiting battery durability [1]. 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 [2]. On the other hand, electrochemical dissolution (ED) of nanostructured interfaces is the main cause of material degradation in exposed environments (corrosion) or energy conversion and storage devices. Dissolution is also affected by random initiation events, fast kinetics and surface heterogeneity. Hence, a complete picture of the (combination of) dissolution pathways taking place is also elusive.

To address these challenges, we combine Scanning Electrochemical Cell Microscopy (SECCM) and in-situ Electrochemical Transmission Electron Microscopy (EC-TEM).

On the one hand, we performed thousands of high-throughput local electrochemical measurements for the nucleation of Au and Cu on different surfaces such as glassy carbon (GC), ITO, and Pt [3-4], which we analyzed with a data-centric approach. In addition, the spatially resolved electrochemical characterization enables a one-to-one correlation between the electrochemical data and the local surface properties, which are evaluated by SEM in identical locations to where the local electrochemical measurements have been performed.

On the other hand, we use SECCM as a high throughput tool to collect ED activity from randomly probed locations where metal nanoparticles (NPs) are pre-deposited by different methods (electrodeposition, sputtering, drop casting, etc.). Taking gold NPs as a case study, we show that, in the presence of chloride and at certain potentials, NP dissolution events are separated in time and can be therefore monitored by SECCM as single NP dissolution events [3, 5]. Data science methods, previously applied in the group for the study of pitting corrosion in stainless steel [6, 7] have been here deployed to explore the very large datasets containing information of the dissolution of several thousands of NPs.

The analysis of the SECCM EN&G and ED datasets is leveraged to discuss mechanistic aspects of noble metal nucleation, growth and dissolution processes. In addition, we show how EC-TEM allows the study of the early-stage growth/dissolution dynamics of the metallic phase. Interestingly, these measurements corroborate that the nature of the events resolved by SECCM corresponds to the dissolution of individual NPs. The combination of high-throughput SECCM, EC-TEM and data-centric analysis opens new opportunities for the rational design (electrodeposition) of functional nanostructured materials and the evaluation of their durability under electrochemical polarization (resistance to electrodissolution).