One-pot synthesis of ZnO quantum dots/N-doped Ti3C2 MXene: Tunable nitrogen-doping properties and efficient electrochemiluminescence sensing

Nitrogen doping has been proven to be a facile modification strategy to improve the electrochemical performance of 2D MXenes, and thus broaden the potential of MXene-based materials in electrochemistry. Herein, a unique 0D/2D heterostructure of ZnO quantum dots (QDs) decorated nitrogen-doped Ti3C2 MXene (ZnO/N-Ti3C2) with high nitrogen-doping level has been designed and prepared using glycine as N precursor via a facile thermal treatment. During the synthesis process, Ti3C2 MXene matrix acted as an important role to confine the nucleation and growth of ZnO QDs, and thus resulted in the well-dispersed ZnO QDs of 2 similar to 5 nm on the surface of MXene. Meanwhile, the nitrogen-doping level of Ti3C2 MXene in the composites can be simply tuned from 1.52 wt% to 5.43 wt% by adjusting the amount of glycine. Electrochemical measurements demonstrated that the increasing doping contents in Ti3C2 MXene could boost the Electrochemiluminescence (ECL) performances, which might be attributed to that more nitrogen contents were beneficial for accelerating electron transfer and decreasing the barrier of ZnO QDs reduction. Remarkably, ECL testing of the ZnO/N-Ti3C2 with 5.43 wt% N revealed that the ECL intensity enhanced by 2.8-fold and the ECL onset potential increased for about 250 mV than those of ZnO QDs/undoped Ti3C2 MXene. By using the resultant ZnO/N-Ti3C2 nanocomposites as an efficient ECL platform, a novel ECL sensor was constructed for sensitive and selective detection of chloramphenicol, which displayed a wide linear range (0.1 ng/mL similar to 100 ng/mL), a low detection limit (0.019 ng/mL) and high stability.