Sr@FeNi-S Nanoparticle/Carbon Nanotube Nanocomposite with Superior Electrocatalytic Activity for Electrochemical Detection of Toxic Mercury(II)

In this work, we developed a Sr-doped FeNi-S nanoparticle by a simple one-step pyrolysis process and successfully integrated it with single-walled carbon nanotubes (Sr@FeNi-S/SWCNTs) using an ultrasonication method. The Sr@FeNi-S/SWCNTs nanocomposite consisted of Sr, Fe, Ni, and S atoms inside the nanosized particle of Sr@FeNi-S firmly anchored on the surface of the SWCNTs. Electrochemical impedance analysis of the Sr@FeNi-S/SWCNTs electrode shows favorable kinetic charges for transport compared to those of Sr@FeNi-S and SWCNTs. A glassy carbon electrode modified with Sr@FeNi-S/SWCNTs is constructed and used for the selective and sensitive electrochemical determination of trace amounts of mercury (Hg(II)). The electrochemical behavior of the modified electrode and the mechanism of the Hg(II) were investigated by cyclic voltammetry. By differential pulse voltammetry at optimum parameters such as a wide linear range (WLR: 0.05–279 μM), an ultralow level detection limit (LOD: 0.52 nM) of Hg(II) is observed with a sensitivity of 1.838 μA μM–1 cm–2. The practical feasibility of the electrode was assessed in lake water and river water samples with satisfactory recovery results of Hg(II) added. Moreover, this work not only demonstrates the tremendous potential of electrochemical detection of Hg(II) but also highlights a simple and robust methodology to develop material discovery and design for improved electrochemical performance.