A unique bimetallic MOF derived carbon–MWCNTs hybrid structure for selective electrochemical determination of lead ion in aqueous solution.

• Co-N x -C@MWCNTs with 3D braided structure is derived from bimetal ZIF with MWCNTs. • Highly porous Co-N x -C@MWCNTs possesses abundant active sites of Co-N x. • Co-N x -C@MWCNTs based sensor shows excellent sensitivity and selectivity for Pb(II) • Co-N x -C@MWCNTs based sensor shows feasibility in real water analyses. The first trial for electrochemical determination of Pb(II) with a bimetal organic framework derived composite, denoted as Co-N x -C@MWCNTs, is demonstrated in this work. The Co-N x -C@MWCNTs with three dimensionally braided structure was fabricated on the basis of zinc/cobalt co-centered bimetal zeolite imidazole framework (BMZIF-67) and interlaced with multi-walled carbon nanotubes (MWCNTs). Contributable to the presence of zinc/cobalt co-centers and the nitrogen-containing ligands, the homogenous dispersion of metallic cobalt and the formation of Co-N x moieties which were widely known as active sites in electrocatalysts were fulfilled. The integration of MWCNTs resulted in enhanced conductivity and extra porosity, which were also crucial for electrochemical sensing. Therefore, Co-N x -C@MWCNTs based electrochemical sensor exhibits good reliability for Pb(II) detection, with a low detection limit of 0.7 μg L−1 over a wide linear range of 2–60 μg L−1. This design may shed lights on the fabrication of bimetal organic frameworks based electrochemical sensors in general. [ABSTRACT FROM AUTHOR]