A high performance Pb(II) electrochemical sensor based on spherical CuS nanoparticle anchored g-CN.

A new electrochemical sensor has been constructed for ultra-sensitive detection of lead ions (Pb) by square wave anodic stripping voltammetry (SWASV), based on the copper sulfide/graphitic carbon nitride nanocomposite modified glassy carbon electrode (CuS/g-CN/GCE). First, spherical CuS nanoparticles with good electrical conductivity were anchored on layered g-CN with high coordination activity, affording an excellent electrode modifier CuS/g-CN nanocomposite. Then, the performance of the CuS/g-CN/GCE and its electrochemical response to Pb were thoroughly studied, and the sensing mechanism was investigated. On the one hand, the CuS/g-CN nanocomposite has greatly improved the electron transportation and electrode performance through functional complementarity - CuS endows g-CN with a good electrical conductivity and a large active specific surface area, while g-CN endows CuS with high dispersibility and strong adsorption. On the other hand, the CuS/g-CN modifier has effectively promoted the deposition of trace Pb from the solution onto the electrode surface by means of synergistic enrichment (crucial for amplification of detection signals) - g-CN can coordinate with Pb by its large number of conjugated triazine heterocyclic rings in its molecular framework, while CuS can adsorb Pb due to its inherent size effect of nanomaterials. The proposed sensor can efficiently detect Pb in the concentration range of 0.050-5.000 μM with a limit of detection (LOD) as low as 4.00 nM, and can be well applied for the detection of trace Pb in actual tea samples.