Designing advanced 0D/2D heterojunctions of N, S-co-doped carbon dots/Ti3C2Tx MXene nanosheets in electrochemical sensor applications

Ti3C2Tx MXene has demonstrated well-established sensitivity in electrochemical sensing but is susceptible to oxidation. Nitrogen-sulfur doped carbon dots (N, S-CDs) were functionalized on Ti3C2Tx MXene nanosheets via a surface modification strategy, leading to significant enhancement in the performance of Ti3C2Tx MXene. The incorporation of N, S-CDs into Ti3C2Tx MXene nanosheets effectively prevents the aggregation of Ti3C2Tx MXene flakes, resulting in improvement of the interlayer spacing to 1.578 nm and a threefold expansion of the specific surface area. Furthermore, the N, S-CDs contribute to increase the effective active surface area of the Ti3C2Tx MXene electrode, facilitating accelerated the electron transfer rates and providing additional active sites. On this basis, a galvanic sensor for dopamine (DA) detection was attained through loading N, S-CDs/Ti3C2Tx on glassy carbon electrodes. The optimized sensor achieved a linear detection range of 1 μM–1000 μM for DA, with a detection limit of 0.91 μM (S/N = 3). This work presents a promising approach for the utilization of chemically stable Ti3C2Tx MXene and MXene-based sensors, offering a new avenue for quantitative detection of DA that holds potential for application in real sample analysis.