Synthesis driven by renewable electricity offers a sustainable, scalable, decentralized, and energy-efficient route to furnish value-added products – from fuels to complex molecules. Maximizing reaction efficiency and durability requires immobilized catalytic active sites on electrodes, resulting in dispersed and non-uniform sites. This heterogeneity challenges iterative optimization of reactivity through traditional catalyst modifications, which rely on uniform, singular active sites. This lecture will focus on our research developing synthetic tools and concepts to predictively control interfacial structures at heterogeneous and reusable electrodes at the molecular level. Surface-sensitive techniques and mechanisms will be highlighted throughout the talk. Applications of our interfacial designs in enabling selective chemical syntheses and durable energy conversion systems will be discussed.