Tin electrodeposition applications have rapidly evolved in the past 25 years. Usage of tin coatings has advanced from being mainly used for corrosion protection and decorative purposes, to being... Show moreTin electrodeposition applications have rapidly evolved in the past 25 years. Usage of tin coatings has advanced from being mainly used for corrosion protection and decorative purposes, to being used in modern technology such in electronic devices, photovoltaic cells and Li-ion batteries. The new tin coating applications have also come with challenges that require the production of nanostructured deposits, multilayers coatings and composites. Furthermore, the need to reduce energy and source consumptions, and the implementation of more environment-friendly processes, require detailed and fundamental knowledge of the electrodeposition process.The emphasis throughout this thesis is therefore to obtain detailed mechanistic information of tin electrodeposition process.The experimental and theoretical work presented in this thesis attempts to understand the mechanism of tin electrodeposition, and the effect of electrolyte anions and naphthalene-based additives, during the early and subsequent stages of the process. Show less
In this work, we have studied tin electrodeposition on polycrystalline gold electrodes from two different supporting electrolytes: sulfuric acid (SA) and methanesulfonic acid (MSA), both of them... Show moreIn this work, we have studied tin electrodeposition on polycrystalline gold electrodes from two different supporting electrolytes: sulfuric acid (SA) and methanesulfonic acid (MSA), both of them commonly used in the industry. This work aims to understand the effect of the different electrolyte anions on the deposition process. We show at least three different tin deposition mechanisms on gold: irreversible adsorption, underpotential deposition, and overpotential (bulk) deposition. Underpotential deposition leads to the formation of a layer of tin in SA and MSA with a coverage around θSn(H2SO4)=0.45θSn(H2SO4)=0.45 ML (monolayer) and θSn(CH3SO3H)=0.42θSn(CH3SO3H)=0.42 ML, respectively. The UPD Sn layer is however somewhat uncharacteristic as it is associated with island formation and surface alloying. Cyclic voltammograms in an extended potential range showed five distinct peaks: two cathodic peaks associated with tin underpotential and overpotential deposition, and three main anodic peaks, corresponding to the oxidation of the bulk Sn, of the AuSn intermetallic layer, and of the adsorbed Sn(II) to Sn(IV). Both voltammetric and rotating disk electrode measurements show that the kinetics of tin electrodeposition in MSA is slower than in SA, which we ascribe to Sn-MSA complex formation in solution. Slow Sn deposition in MSA promotes AuSn formation, in contrast to SA in which bulk tin deposition is more prominent. Complete Levich-type mass transport control of tin deposition in SA and MSA was only reached at low scan rate due to concurrent HER on the uncovered gold surface during the deposition process at higher scan rates. An unexpected surface-confined passivation process is observed in both electrolytes. Show less
