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Micro-and macro-scale electrochemical study for nucleation and growth of metallic particles on ITO

par Bailly, Jérôme
Président du jury Luhmer, Michel
Promoteur Ustarroz Troyano, Jon
Publication Non publié, 2022-06-27

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Résumé :

Recently, deposition of metallic particles has gained unprecedented attention due to their unique properties and numerous applications in the energy and electronics industry. Electrodeposition, quickly became an attractive method to perform deposition due to its numerous advantages. However, the deposited material is highly affected by the substrate and experimental conditions, meaning that it is crucial to understand the initial formation stages of metallic particles. However, current models to understand nucleation and growth are incomplete, as there are still discrepancies regarding the mechanistic understanding of the process. Especially for tin-doped indium oxide (ITO) substrates that has not been studied in such detail, despite its numerous useful properties and applications. Therefore, this work studies nucleation and growth of metallic particles on ITO in acidic media. It is divided in two parts, the first is focused on macro-scale electrochemical response of ITO whilst the second one investigates the local (micro-scale) electrochemical response. First, electrochemical and chemical stability of ITO through cathodic polarization is investigated in different acidic media, showing significant morphological and chemical changes. Then, differences in nucleation and growth of silver and copper particles is investigated through cyclic voltammetry and surface analysis. Different explanations are detailed to shed light on those discrepancies. Finally, the effect of electrochemical pretreatment of the surface on deposition is investigated and shows that ITO's activity toward nucleation can be engineered, allowing to have a certain control on the deposition process.At last, nucleation of silver and copper nanoparticles on an ITO substrate has been studied for the first time with a local electrochemical approach based on Scanning Electrochemical Cell Microscopy (SECCM). A distribution of responses for nucleation was found when scanning multiple regions of the substrate, which highlights the statistical nature of the nucleation and growth process at the micro-scale and brings new insights on the effect of surface heterogeneity on nucleation.