Ion (de)solvation at solid–electrolyte interfaces is pivotal for energy and chemical conversion technology, such as (electro)catalysis, batteries and bipolar membranes. For example, during the electrocatalytic hydrogen evolution reaction in alkaline media, water needs to be dissociated and hydroxide ions solvated—a process that is not well understood. Here we study water dissociation and ion solvation kinetics in isolation at polymeric bipolar membrane and electrolyte–metal interfaces. We discover bias-dependent relationships between the activation entropy and enthalpy, which we link to a bias-dependent dispersion of interfacial capacitance. Furthermore, our results indicate that OH⁻ solvation is kinetically slower than H⁺ solvation and that the solvation kinetics display characteristics that are independent of the catalyst structure. We attribute this to a universal amount of excess charge needed to induce electric fields that alter the interfacial entropy of water. Of fundamental interest, these results are critical to enable knowledge-driven bipolar membrane and electrocatalyst design.

固体电解质界面的离子（去）溶剂化对于（电）催化、电池和双极膜等能源和化学转化技术至关重要。例如，在碱性介质中的电催化析氢反应过程中，水需要解离，氢氧根离子需要溶剂化——这一过程尚不清楚。在这里，我们研究了聚合物双极膜和电解质-金属界面上的水离解和离子溶剂化动力学。我们发现激活熵和焓之间存在偏压相关关系，并将其与界面电容的偏压相关色散联系起来。此外，我们的结果表明，OH ^-溶剂化在动力学上比 H ⁺溶剂化慢，并且溶剂化动力学表现出与催化剂结构无关的特征。我们将此归因于感应改变水界面熵的电场所需的普遍过量电荷。具有根本意义的是，这些结果对于实现知识驱动的双极膜和电催化剂设计至关重要。