Dynamic active sites behind Cu-based electrocatalysts: Original or restructuring-induced catalytic activity

<h2>Summary</h2> Structural dynamics in electrocatalysts under operating conditions, including restructuring, dissolution/redeposition, and single-site-to-cluster transitions, are commonly observed phenomena but are often poorly understood. Cu-based catalysts, entailing single-atom catalysts (SACs), molecular catalysts, and nanostructured catalysts, have shown promise in key electrochemical reactions such as CO₂ reduction, NO₃⁻ reduction, and C–N coupling and are particularly prone to structural changes as they carry out these reactions. While the fully accurate prediction of restructuring-induced activity remains an ongoing challenge, this review offers a comprehensive analysis of Cu-based catalysts, focusing on the dynamic behavior of Cu active sites, which can undergo structural changes during electrocatalytic reactions, thereby impacting catalytic performance and selectivity. Taking insights from advanced <i>in situ</i>/<i>operando</i> techniques, such as X-ray absorption spectroscopy (XAS), this study identifies and evaluates a set of Cu-based electrocatalysts under electrocatalytic reduction reactions and distinguishes the dynamic active sites between original and restructuring-induced forms.