Simple and rapid mercury ion selective electrode based on 1-undecanethiol assembled Au substrate and its recognition mechanism

- A simple and rapid mercury ion selective electrode has been well constructed.
- The Au/1-UDT electrode for sensing Hg2 + has a sensitivity of 28.83 ± 0.4 mV/− pC.
- The ISE method has a detection limit of Hg2 + down to 4.5 × 10− 9 mol L− 1.
- A mechanism with density functional theory for recognition of Hg2 + is developed.
- The quantum chemical computation demonstrates Au-Hg metallophilic interaction.

A simple and rapid mercury ion selective electrode based on 1-undecanethiol (1-UDT) assembled Au substrate (Au/1-UDT) has been well constructed. 1-UDT was for the purpose of generating self-assembled monolayer on gold surface to recognize Hg2+ in aqueous solution, which had a working concentration range of 1.0 × 10− 8-1.0 × 10− 4 mol L− 1, with a Nernst response slope of 28.83 ± 0.4 mV/-pC, a detection limit of 4.5 × 10− 9 mol L− 1, and a good selectivity over the other tested cations. Also, the Au/1-UDT possessed good reproducibility, stability, and short response time. The recovery obtained for the determination of mercury ion in practical tremella samples was in the range of 99.8-103.4%. Combined electrochemical analysis and X-ray photoelectron spectroscopy (XPS) with quantum chemical computation, the probable recognition mechanism of the electrode for selective recognition of Hg2+ has been investigated. The covalent bond formed between mercury and sulfur is stronger than the one between gold and sulfur and thus prevents the adsorption of 1-UDT molecules on the gold surface. The quantum chemical computation with density functional theory further demonstrates that the strong interaction between the mercury atom and the sulfur atom on the gold surface leads to the gold sulfur bond ruptured and the gold mercury metallophilic interaction.

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