Efficient ultra-trace electrochemical detection of Cd2+, Pb2+ and Hg2+ based on hierarchical porous S-doped C3N4 tube bundles/graphene nanosheets composite

In this paper, the synergistic effect between sulfur-doped C3N4 tube bundles (STB) with hierarchical pores and graphene nanosheets (Gs) is beneficial for ultra-trace heavy metal ions (HMIs) detection and makes STB/Gs composite a promising sensitive electrochemical sensor for HMIs detection. The excellent trace HMIs detection performance was attributed to the adsorption of hierarchical porous tube bundle structure and the increasing of active sites by S atom doping. Firstly, the hierarchical porous STB/Gs composite used in electrochemical sensor was successfully prepared by hydrogen bond supramolecular self-assembly, evaporation-induced drying and electrostatic assembly methods. Also, under optimized conditions, the sensitivities were 19.87, 44.77 and 29.51 μA/μM and the limit of detection were 1.17, 0.38 and 0.61 nM for simultaneous detection of Cd2+, Pb2+ and Hg2+. The sensitivities were 10.13, 21.68 and 15.71 μA/μM and the limit of detection were 2.30, 0.78 and 1.15 nM for individual detection of Cd2+, Pb2+ and Hg2+. Little interference effects from other co-existing ions allowed the sensor to work in natural water environment for practical application. This method of STB/Gs composite might show utility for constructing highly sensitive electrochemical sensors for the trace detection of heavy metal ions.