A unifying theme of my research program is the pursuit of fundamental chemical understanding through the use of optical, electrical, and magnetic external fields to measure, drive, and control interfacial chemical transformations at the nanoscale. At its core, our work seeks to elucidate the physical chemistry governing the interconversion of chemical and electrical energy in electrocatalytic systems. We pursue this objective through two complementary strategies: (1) controlling the local microenvironment at the electrode–electrolyte interface to enhance activity and selectivity, and (2) developing and applying high-resolution optical microscopy and spectroscopy to reduce ensemble averaging in electrocatalysis and directly measure surface species and reaction intermediates. These approaches emphasize mechanistic understanding and aim to provide generalizable principles that can be leveraged to design more efficient and selective catalysts for fuel generation and consumption reactions, as well as small-molecule transformations relevant to energy and organic synthesis.