Unraveling Multiscale Interfacial Dynamics for High‐Flux Hydrogen Peroxide Electrosynthesis

ABSTRACT Electrochemical hydrogen peroxide (H 2 O 2 ) synthesis via the two‐electron oxygen reduction reaction (2e − ORR) is evolving from active‐site optimization toward multiscale interfacial regulation under industrially relevant conditions. This review establishes a cross‐scale framework linking molecular‐scale electrochemical microenvironments, mesoscale gas–liquid–solid triple‐phase interfaces, and macroscopic electrode/reactor architectures to the selectivity, mass‐transport efficiency, and durability of H 2 O 2 electrosynthesis. At the molecular scale, local pH, alkali metal cations, and organic additives reconstruct the electric double layer by modulating proton activity, interfacial electric fields, and ionic identity, thereby governing proton‐coupled electron‐transfer kinetics and *OOH stability. At the mesoscale, interfacial wettability, micro‐/nano‐architectures, and operando triple‐phase interface stability collectively regulate O 2 transport, proton accessibility, and H 2 O 2 evacuation under high‐current operation. At the device scale, we evaluate how gas‐diffusion electrodes and reactor configurations coordinate multiphase transport and interfacial stability to sustain industrially relevant current densities during long‐term operation. Particular attention is devoted to the intrinsic coupling among molecular‐scale reaction environments, mesoscale transport processes, and macroscopic stability, highlighting the necessity of cross‐scale synergistic regulation to achieve both high selectivity and durability. Finally, we discuss emerging opportunities in operando characterization, multiscale simulation, and interface–device co‐design for scalable H 2 O 2 electrosynthesis.