Metal–Support Interactions in Heterogeneous Electrocatalysis

Abstract Electrochemical energy conversion underpins the sustainable production of fuels and chemicals, with efficiency and selectivity governed by reactions at electrified solid–liquid interfaces. In supported electrocatalysts, metal–support interactions (MSIs) shape how catalytic states form and persist under polarization. Yet a predictive description of MSI remains elusive. The as-prepared contact may reconstruct under operating conditions. Activity shifts, morphology, and charge redistribution do not uniquely identify the current-carrying ensemble. These limitations motivate this review, which separates interfacial structure, chemical bonding, and collective adhesion before relating them to catalytic function. The framework spans single atoms, clusters, nanoparticles, core–shell architectures, and reconstructed interphases. We assess how atomic-resolution imaging, operando characterization, and potential-aware calculations constrain models of the working interface and relate them to electrocatalytic performance. Together, these analyses show that MSI effects depend on the working interfacial state and its reaction environment. Predictive design therefore requires balancing interfacial stabilization with the active-site accessibility and structural adaptability needed for turnover.