Fe/NC single-atom catalysts have attracted in depth consideration because of their maximal atomic utilization and tunable coordination environments. Nonetheless, the structure-activity relationship of Fe single atoms in electrooxidation stays unclear. Herein, we report a defect engineering technique to fine-tune the cost configuration of FeN4 websites by introducing an axial N ligand and establishing FeN5-Fe1/NC. This uneven coordination atmosphere enhances the catalytic exercise for dopamine (DA) oxidation, delivering a 2.1-fold enchancment over conventional Fe1/NC. The FeN5-Fe1/NC biosensor reveals a large linear detection vary of 0.05-500 μM with a low detection restrict of 23 nM for DA. Moreover, theoretical calculations verify that axial N coordination modulates the digital construction of the Fe heart, optimizes intermediate adsorption, and lowers the vitality barrier for DA oxidation. This work gives invaluable insights into the rational design of single-atom catalysts for high-performance electrochemical sensing and basic mechanistic research on the atomic scale.
