Simultaneous Electrochemical Detection of Cd2+ and Pb2+ Based on an MOF-Derived Carbon Composite Linked with Multiwalled Carbon Nanotubes

Heavy metal ion (HMI) pollution is a serious threat to human health and the ecosystem. Therefore, there is an urgent need to develop a fast and sensitive platform for heavy metal ion detection. In this work, a novel sensing platform based on ZIF-67-derived cobalt/nitrogen-doped carbon (NC) composite polyhedrons linked with multiwalled carbon nanotubes (MWCNTs), termed Co@NC/MWCNT, for the simultaneous monitoring of Cd2+ and Pb2+ was established. In detail, nanoporous ZIF-67 was first in situ grown on the MWCNTs, followed by carbonization, endowing the composite with good electrical conductivity and a large specific surface area, providing more active sites for subsequent metal ion attachment. Under optimal parameters, the proposed sensing platform exhibited a relatively wider linear range of 0.12–2.5 μM, with lower limits of detection (LODs) of 4.5 nM (Cd2+) and 4.9 nM (Pb2+). Notably, it was worth mentioning that the linearity of the as-prepared sensing platform in the actual water sample was highly consistent with the linearity in the buffer solution, showing outstanding anti-interference performance. Finally, the designed sensing platform performed well in several kinds of natural water environment when compared with the standard method, demonstrating huge potential in trace HMI monitoring.