COFBTLP-1/three-dimensional macroporous carbon electrode for simultaneous electrochemical detection of Cd2+, Pb2+, Cu2+ and Hg2+

The indissolubility or poor dissolubility of covalent-organic frameworks (COFs) limits their wide applications. Here, the COFBTLP-1 which were prepared by the aminaldehyde condensation between 1,4-benzenedithiol-2,5-diamino-hydrochloride and 1,3,5-triformylbenzene was controllably grown on kenaf stem-derived macroporous carbon (3D-KSC). Compared with COFBTLP-1 powder, the COFBTLP-1 grown on 3D-KSC avoided their random orientation effectively. The results showed that the amount of COFBTLP-1 could be effectively controlled by adjusting the concentration of monomers and growing time. Each unit of COFBTLP-1 has 12 adsorption sites (6 sulfur atoms and 6 nitrogen atoms) for heavy metal ions (HMIs) and regular holes to facilitate the transfer of HMIs. A large number of adsorption sites of HMIs could identify and captured HMIs selectively, and accordingly Cd2+, Pb2+, Cu2+ and Hg2+ could be detected simultaneously by using the COFBTLP-1/3D-KSC electrode. The detection limits for Cd2+, Pb2+, Cu2+ and Hg2+ are 12.3 nM, 11.8 nM, 18.6 nM and 21.4 nM, respectively. The sensitivities are up to 1337.4 μA/μM cm2, 1389.0 μA/μM cm2 and 886.2 μA/μM cm2, 770.0 μA/μM cm2, respectively. The COFBTLP-1/3D-KSC may be also applied in other fields of electroanalytical chemistry.