Electrochemiluminescence (ECL) originates from excited-state species produced by electrochemical redox processes and has traditionally been attributed exclusively to the working electrode (WE), with the counter electrode (CE) regarded as electrochemically inert. Herein, we fundamentally challenge this paradigm by employing the single/dual-atom iron-doped hollow carbon spheres (Fe-HCS-T) as coreactant accelerants of the luminol-dissolved oxygen (DO) system. The coating of Fe-HCS-T not only catalyzes the formation of reactive oxygen species (ROS) at WE but also modulates the interfacial potential at the CE, thus triggering the luminol electro-oxidation at the CE. And the interelectrode coupling between luminol electro-oxidation and oxygen reduction reaction (ORR) enable high efficiency ECL at 0.025 V. Spatially- and potential-resolved ECL mapping, combined with radical-quenching studies and complementary electrochemical analyses, indicates a synergistic WE-CE coupling reaction mechanism that markedly amplifies light output. Leveraging this coupling effect, the Fe-HCS-T-based platform enables ultrasensitive Trolox detection across a dynamic range of 0.1 nM-10 mM. These results fundamentally challenge the conventional paradigm for ECL systems and highlight interelectrode coupling as a powerful strategy to boost ECL performance and expand capabilities in advanced sensing applications.
Zhang et al. (Wed,) studied this question.