Nanometer-Resolved Observation of Electrochemical Microenvironment Formation at the Nanoparticle–Ligand Interface

The electrocatalytic microenvironment surrounding nanocatalysts plays a pivotal role in dictating catalytic reactivity and selectivity by influencing solvent orientation, counterion solvation, reactant transportation, and the stabilization of intermediates near active sites. Despite its importance, the rational design of nanocatalysts with optimized microenvironments remains underdeveloped, primarily due to a limited molecular-level understanding of microenvironment formation and evolution at the electrolyte–nanocatalyst interface. In situ and operando techniques with nanometer-scale spatial resolution and chemical sensitivity are therefore essential for revealing the real-time molecular dynamics of this interface. In our recent work, we utilized in situ Fourier transform infrared nanospectroscopy (nano-FTIR) to successfully capture the formation of an electrochemical microenvironment that promotes CO₂ electroreduction at the nanoparticle–ligand interface. Complemented by Surface Enhanced Raman Spectroscopy (SERS), we uncovered a bias-induced consecutive ligand dissociation mechanism in aggregating silver nanoparticles. These findings provide critical insights for guiding the rational design of electrocatalysts by tracking the structural evolution of nanoparticle-ligand systems. Moreover, the methodology we present is broadly applicable to studying the dynamic response of interfacial species—such as capping ligands, reaction intermediates, and solvent molecules—to various external stimuli at nanometer resolution, thereby substantially facilitating the mechanistic understanding of how the molecular-level events ultimately lead to specific NP functionalities.