Coupling Electron Transfer with Ion Transport-Amplified Electrochemiluminescence Signals

Electrochemiluminescence (ECL) intensity is simultaneously influenced by both the electron-transfer and mass transport processes. However, the current concerns with ECL amplification focus on either electron transfer or ion transport. In this contribution, luminol-dissolved O₂ ECL amplification from coupled electron and ion transport properties of conductive polymers (CPs) was investigated in detail by employing poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as a model CP. The anodic ECL of luminol-dissolved O₂ at a PEDOT:PSS-modified indium tin oxide (ITO) electrode exhibited a 15-fold signal amplification in comparison to that of bare ITO. Further mechanistic investigations revealed that PEDOT could facilitate the electron-transfer process and promote both the conversion of O₂ into superoxide radicals and the transition of luminol anions to anion radicals. Additionally, the porous structure and electrochemical doping of the swollen PEDOT:PSS film enabled the transport of luminol anions, synergistically increasing the ECL intensity. This work provides a basis for designing CP-based ECL amplification platforms by leveraging the coupled electron and ion transport to govern ECL emission in the luminol-dissolved O₂ system.