Ion the prize The dynamic role of ions at the solid-liquid interface

Understanding solid–liquid interfacial interactions is essential for controlling chemical reactivity, material synthesis, and electrochemical behaviour. These interfaces play a key role in a wide range of applications, from energy conversion and storage to the fabrication of functional materials. This thesis examines how ions in solution influence the organization of solvent molecules and the energetics at interfaces, both in equilibrium and under applied potential. The first part of the thesis focuses on the solution-based synthesis of low-dimensional perovskite materials, particularly butylammonium lead iodide. It demonstrates that the oxidation state of the lead precursors (Pb²⁺ versus Pb⁴⁺) significantly impacts ion-solvent complexation, leading to distinct crystallization behaviours and morphologies. These findings underscore the importance of precursor chemistry in directing material formation at the molecular level. The second part of the thesis applies Electrochemical Atomic Force Microscopy to quantitatively map adhesion forces at electrified interfaces with high spatial resolution. By examining various electrolyte compositions and electrode materials, the thesis reveals how interfacial forces depend on ion identity, surface structure, and electrochemical conditions. These findings provide insights into the nanoscale organization of the electric double layer and uncover ion-specific effects that challenge traditional models of electrochemical interfaces. This thesis highlights the active and dynamic interplay of all system components, including ions, solvents, and solid surfaces, in shaping interfacial structure, chemical pathways, and electrochemical behaviour.