Advanced electrochemical sensors for the simultaneous detection of nitrophenol isomers: the synergistic effects in MXene/β-cyclodextrin composites.

In this work, a series of cyclodextrins (CDs) was selected to construct composites with MXene for enhancing electrochemical detection performance toward three nitrophenol isomers (NPs). Subsequently, the composites were utilized to modify glassy carbon electrode (GCE) for fabricating sensing electrodes. Through comparative study, the composite based on MXene and β-cyclodextrin (MXene/β-CD) exhibited the most excellent electrochemical sensing performance. MXene/β-CD was characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), infrared spectroscopy (FTIR), and electrochemical measurements. The excellent performance would be caused by not only the synergistic effect from MXene (rich specific surface area, active functional site and high conductivity) and β-CD (host-guest recognition ability), but also good compatibility between MXene and β-CD (the improved stability and compatibility due to charge-balancing). Under optimal condition, the MXene/β-CD/GCE showed a wide linear range for detecting o-nitrophenol (o-NP) of 0.4-350 μM, m-nitrophenol (m-NP) of 0.5-300 μM, and p-nitrophenol (p-NP) of 0.5-180 μM. The limits of detection were found to be 0.063 μM for o-NP, 0.087 μM for m-NP, and 0.042 μM for p-NP, respectively. Additionally, the developed sensor demonstrated high selectivity, reproducibility and long-term stability, and satisfactory applicability in real environmental samples. This work provides the foundation for the advanced electrodes development in environmental sensing applications.