Strategy and mechanism for strong and stable electrochemiluminescence of graphitic carbon nitride

Abstract

Electrochemiluminescence (ECL) of graphitic carbon nitride nanosheets (CNNSs) is showing extensive interest to researchers. However, the poor ECL stability of CNNSs has always been an urgent problem, which severely limits its application. Herein, a systemic investigation is carried out for the exact mechanism affecting the ECL stability of CNNSs. It is found experimentally that dissolved oxygen in the solution is selectively reduced into H2O2 through a two-electron pathway on the surface of CNNSs. The enriched electrogenerated H2O2 on the electrode surface leads to the progressive inhibition of ECL of CNNSs due to its competition with negatively charged CNNSs (CNNSs•–) for sulfate radical ions (SO4•–). On the basis, the pathway of eliminating O2 by N2, composing CNNSs with other nanomaterials to realize the four-electron reduction, or improving the concentration of K2S2O8 is proved to be effective means for improving ECL stability successfully. Proofing the concept of CNNSs with high ECL stability, an ECL sensor is developed for the detection of H2O2. This work not only exploits the intrinsic mechanism of poor ECL stability of CNNSs, but also provides efficient methods to improve the ECL stability. Thus, we believe it has promising attraction in the research of CNNSs-based assays.