Electrified solid–liquid interfaces (ESLIs) play a key role in various electrochemical processes relevant to energy^1,2,3,4,5, biology⁶ and geochemistry⁷. The electron and mass transport at the electrified interfaces may result in structural modifications that markedly influence the reaction pathways. For example, electrocatalyst surface restructuring during reactions can substantially affect the catalysis mechanisms and reaction products^1,2,3. Despite its importance, direct probing the atomic dynamics of solid–liquid interfaces under electric biasing is challenging owing to the nature of being buried in liquid electrolytes and the limited spatial resolution of current techniques for in situ imaging through liquids. Here, with our development of advanced polymer electrochemical liquid cells for transmission electron microscopy (TEM), we are able to directly monitor the atomic dynamics of ESLIs during copper (Cu)-catalysed CO₂ electroreduction reactions (CO₂ERs). Our observation reveals a fluctuating liquid-like amorphous interphase. It undergoes reversible crystalline–amorphous structural transformations and flows along the electrified Cu surface, thus mediating the crystalline Cu surface restructuring and mass loss through the interphase layer. The combination of real-time observation and theoretical calculations unveils an amorphization-mediated restructuring mechanism resulting from charge-activated surface reactions with the electrolyte. Our results open many opportunities to explore the atomic dynamics and its impact in broad systems involving ESLIs by taking advantage of the in situ imaging capability.

带电固液界面 (ESLI) 在与能源^1,2,3,4,5 、生物学⁶和地球化学⁷相关的各种电化学过程中发挥着关键作用。带电界面处的电子和质量传输可能导致结构改变，从而显着影响反应途径。例如，反应期间的电催化剂表面重组可以显着影响催化机制和反应产物^1,2,3 。尽管其重要性，但由于埋藏在液体电解质中的性质以及当前通过液体进行原位成像的技术的空间分辨率有限，在电偏压下直接探测固液界面的原子动力学仍然具有挑战性。在这里，随着我们开发用于透射电子显微镜 (TEM) 的先进聚合物电化学液体电池，我们能够直接监测铜 (Cu) 催化 CO ₂电还原反应 (CO ₂ ER) 过程中 ESLI 的原子动力学。我们的观察揭示了波动的液体状非晶态界面。它经历可逆的结晶-非晶结构转变并沿着带电的铜表面流动，从而介导结晶铜表面重组和通过界面层的质量损失。实时观察和理论计算的结合揭示了由电荷激活表面与电解质反应产生的非晶化介导的重组机制。我们的结果为利用原位成像功能探索原子动力学及其对涉及 ESLI 的广泛系统的影响提供了许多机会。