Three-Electron Uric Acid Oxidation via Interdistance-Dependent Switching Pathways in Correlated Single-Atom Catalysts for Boosting Sensing Signals

The overly simplistic geometric and electronic structures of single-atom catalysts have become a significant bottleneck in the field of single-atom sensing, impeding both the design of highly efficient electrochemical sensors and the establishment of structure-activity relationships. To address these challenges, we present a novel strategy to boost the sensing performance of single-atom catalysts by precisely tuning the single-atomic interdistance (SAD) in correlated single-atom catalysts (c-SACs). A series of Ru-based c-SACs (Rud=6.2 Å, Rud=7.0 Å, and Rud=9.3 Å) are synthesized with predetermined SAD values, which are comprehensively characterized by various techniques. Electrochemical studies on uric acid (UA) oxidation reveal that Rud=6.2 Å demonstrates an extraordinary sensitivity of 9.83 μA μM-1cm-2, which is superior to most of electrochemistry biosensors reported previously. Kinetic analysis and product examination unveil that the 6.2 Å Ru SAD instigates a distinctive three-electron oxidation of UA, with an extra electron transfer compared to the conventional two-electron pathway, which fundamentally enhances its sensitivity. Density functional theory calculations confirm the optimal SAD facilitates dual-site UA adsorption and accelerated charge transfer dynamics. This investigation provides novel insights into the strategic engineering of high-performance SAC-based electrochemical sensors by precisely controlling the atomic-scale structure of active sites.