The beneficial impact of MXene on the electrochemical performance of graphene quantum dots for dopamine detection

Considerable advancements in nanocomposite design have enabled the development of electrochemical sensors with promising features such as remarkable electrocatalytic activity, high electrical conductivity, and effective surface area. For instance, designing nanocomposites using 2D MXenes and 0D nanomaterials can be beneficial to combine the advantages of both individual constituents in order to enhance the device's final performance. Herein, we developed a nanocomposite based on Ti3C2 MXene to tailor the electrochemical properties of graphene quantum dots (GQDs) for sensing applications. Specifically, the electrochemical properties of different Ti3C2:GQDs ratios were evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. Under optimized conditions, the nanocomposite-based sensor showed a linear response to dopamine (DA) in the concentration range of 40 - 400 mu M and a limit of detection of 1.8 mu M. Moreover, real sample analysis indicated that spiked DA could be determined accurately by Ti3C2/GQDs/GCE in human urine and sweat samples. The improved sensing performance was attributed to the combined effect of the large surface area of GQDs and the electrical conductivity of MXene, which approach can also be extended to develop other electrochemical sensors.