The ion-enriched electrode-electrolyte interface is a unique characteristic of electrocatalytic reactions that can effectively tune the local chemical environment. In this study, we discovered a strong synergy between borate and fluoride anions for water oxidation in neutral conditions. Under an optimal ratio of the two anions, the water oxidation current significantly outperforms the individual counterparts by almost an order of magnitude. This synergy was greatly attributed to the hierarchical anions at the interface, with borate approaching the surface and fluoride extending out, as revealed by in situ surface-enhanced Raman spectroscopy and molecular dynamics simulation. This hierarchical anion arrangement created two kinetics regions, with one borate-dominating region to lower the onset potential and one fluoride-dominating region to sustain a larger current. Using the synergized electrolyte, a low-cost and facilely synthesized Co(OH)₂ electrode could achieve an outstanding performance of 100 mA/cm² at 1.791 V versus RHE under pH = 7.87 with a 2-week-long durability.

离子富集的电极-电解质界面是电催化反应的独特特性，可以有效地调节局部化学环境。在这项研究中，我们发现硼酸盐和氟化物阴离子在中性条件下对水的氧化具有很强的协同作用。在两种阴离子的最佳比例下，水氧化电流显着优于单个对应物几乎一个数量级。这种协同作用很大程度上归因于界面处的分级阴离子，硼酸盐接近表面而氟化物向外延伸，如原位所揭示表面增强拉曼光谱和分子动力学模拟。这种分层阴离子排列产生了两个动力学区域，一个以硼酸盐为主的区域降低起始电位，一个以氟化物为主的区域维持更大的电流。使用协同电解质，低成本且易于合成的 Co(OH) _{2电极可以在 1.791 V 相对于 RHE 在 pH = 7.87 下实现 100 mA/cm} ²的出色性能，并具有 2 周的耐久性。