Single-Atom Iron Enables Strong Low-Triggering-Potential Luminol Cathodic Electrochemiluminescence

The conventional cathodic electrochemiluminescence (ECL) always requires a more negative potential to trigger strong emission, which inevitably damages the bioactivity of targets and decreases the sensitivity and specificity. In this work, iron single-atom catalysts (Fe–N–C SACs) were employed as an efficient co-reaction accelerator for the first time to achieve the impressively cathodic emission of a luminol–H2O2 ECL system at an ultralow potential. Benefiting from the distinct electronic structure, Fe–N–C SACs exhibit remarkable properties for the activation of H2O2 to produce massive reactive oxygen species (ROS) under a negative scanning potential from 0 to −0.2 V. The ROS can oxidize the luminol anions into luminol anion radicals, avoiding the tedious electrochemical oxidation process of luminol. Then, the in situ-formed luminol anion radicals will directly react with ROS for the strong ECL emission. As a proof of concept, sensitive detection of the carcinoembryonic antigen was realized by glucose oxidase-mediated ECL immunoassay, shedding light on the superiority of SACs to construct efficient cathodic ECL systems with low triggering potential.