Ti3C2-MXene@N-doped carbon heterostructure-based electrochemical sensor for simultaneous detection of heavy metals

High-resolution electrochemical sensors with excellent sensitivity and selectivity are urgently needed for simultaneous monitoring of heavy metal ions (HMIs) in the environment. In this study, a nitrogen-doped carbon-coated Ti3C2-MXene heterostructure (Ti3C2@N-C)-based electrochemical sensor was developed for simultaneously determining (Cd2+) and (Pb2+) in seawater and tap water via square wave anodic stripping voltammetry (SWASV). The sensor exhibits excellent performance with a low limit of detection (LOD) (Cd2+ 2.55 nM, Pb2+ 1.10 nM), as well as excellent selectivity in the presence of interfering ions (Zn2+, Fe3+, Fe2+, Co2+, Ni2+, Mn2+, Cu+, Cu2+, and K+) and high resolution for simultaneous detection of Cd2+ and Pb2+. The N-C and Ti3C2-MXene heterostructure improves the conductivity of the composites by accelerating the electron transfer. The nitrogen-doping in Ti3C2@N-C provides adsorbent sites for electrons to coordinate with HMIs. Due to the heterostructure and the coordination by nitrogen, the interface charge transfer is enhanced and the number of selective adsorption sites is increased, improving the metals determination performance. This study proposes a new strategy for improving the electrochemical characteristics of Ti3C2-MXene by using heterostructure and nitrogen-doping effect, and develops a highly sensitive sensor for selective and simultaneous determination of HMIs.