Strong electrochemiluminescent interactions between carbon nitride nanosheet-reduced graphene oxide nanohybrids and folic acid, and ultrasensitive sensing for folic acid

Graphite-like carbon nitride nanosheets (g-C3N4 NSs) have recently emerged as electrochemiluminescent (ECL) nanomaterials and have attracted more and more attention due to their excellent ECL properties and promising applications in ECL sensing. However, the ECL study of g-C3N4 NSs is still in the early stages. Many studies are required to reveal the exact ECL mechanisms of g-C3N4 NSs and thus boost their sensing applications. In this paper, we have investigated ECL interactions between folic acid (FA) and a g-C3N4 NS/S2O82- ECL system at a g-C3N4 NS-reduced graphene oxide (rGO) nanohybrid/glassy carbon electrode in aqueous solutions. Compared with bare g-C3N4 NSs, the nanohybrids of g-C3N4 NS-rGO give a much stable ECL emission due to the prevention of over electrochemical reduction of g-C3N4 by rGO. The stable ECL emission from the g-C3N4 NS-rGO/S2O82- ECL system can be strongly quenched by FA, even in a very low concentration (pM levels). The ECL quenching mechanisms are investigated and discussed in detail. Based on the strong interactions between FA and g-C3N4 NSs, a novel, sensitive, stable and selective ECL sensor has been constructed for the detection of FA, with a wide linear response range from 0.1 to 90 nM, and an excellent detection limit (62 pM). This work not only further clarifies ECL mechanisms of g-C3N4 NSs, but also suggests a promising application of the newly emerging ECL nanomaterial.