As a highly toxic heavy metal ion, mercury ion (Hg2+) pollution has caused serious harm to the environment and human health. In this paper, 4-mercaptopyridine (4-MPY) was selected as the sensing material and decorated on the surface of a gold electrode. Trace Hg2+ could be detected by both differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) methods. The proposed sensor displayed a wide detection range from 0.01 μg/L to 500 μg/L with a low limit of detection (LOD) of 0.002 μg/L by EIS measurements. Combined with molecular simulations and electrochemical analyses, the chelating mechanism between Hg2+ and 4-MPY was explored. Through the analysis of binding energy (BE) values and stability constants, 4-MPY showed an excellent selectivity for Hg2+. In the presence of Hg2+, the coordination of Hg2+ with the pyridine nitrogen of 4-MPY was generated at the sensing region, which caused a change in the electrochemical activity of the electrode surface. Due to the strong specific binding capability, the proposed sensor featured excellent selectivity and an anti-interference capability. Furthermore, the practicality of the sensor for Hg2+ detection was validated with the samples of tap water and pond water, which demonstrated its potential application for on-site environmental detection.

中文翻译：

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用于汞离子灵敏电化学检测的 4-巯基吡啶修饰传感器

汞离子（Hg2+）污染作为一种剧毒重金属离子，对环境和人体健康造成了严重危害。本文选择4-巯基吡啶(4-MPY)作为传感材料并修饰在金电极的表面。微分脉冲伏安法 (DPV) 和电化学阻抗谱 (EIS) 方法均可检测痕量 Hg2+。所提出的传感器显示出从 0.01 μg/L 到 500 μg/L 的宽检测范围，EIS 测量的检测下限 (LOD) 为 0.002 μg/L。结合分子模拟和电化学分析，探讨了Hg2+与4-MPY之间的螯合机制。通过结合能（BE）值和稳定常数的分析，4-MPY对Hg2+表现出优异的选择性。在 Hg2+ 存在的情况下，Hg2+与4-MPY的吡啶氮在传感区域产生配位，引起电极表面电化学活性的变化。由于具有很强的特异性结合能力，该传感器具有优异的选择性和抗干扰能力。此外，通过自来水和池塘水样品验证了该传感器检测Hg2+的实用性，展示了其在现场环境检测中的潜在应用。