Ultrasensitive detection and efficient removal of mercury ions based on covalent organic framework spheres with double active sites

In present work, a new spherical covalent organic framework (TFPB−APTU COF) with good photoelectric property and double active sites (secondary amine (−NH−) group and sulfur (S) atom) was prepared for ultrasensitive detection and efficient removal of mercury ions (Hg2+). The –NH− group and S atom can capture free Hg2+ by coordination and chelation interaction, and the related steric hindrance effect reduces the photocurrent signal of the TFPB−APTU COF, resulting in the highly sensitive photoelectrochemical analysis of Hg2+ with a wide linear response range (0.01−100000 nM) and low detection limit (0.006 nM). On the other hand, the developed TFPB−APTU COF has large removal capacity (2692 mg g−1), good regeneration capability, and high removal speed for Hg2+ removal based on the double active sites (−NH− group and S atom), large specific surface area and porous spherical structure. The developed TFPB−APTU COF spheres show great potential in monitoring and treatment of environmental pollution of Hg2+.