Reliable electrochemical measurements depend on the availability of robust reference electrodes (RE) with well-defined potentials. While many reliable REs are known, they are not applicable in certain demanding media such as ionic liquids, nor in small confined spaces. Here, we describe the fabrication of a simple yet robust Ag/AgS micro-reference electrode (μ-RE) where a micron-thick AgS layer is formed by isothermal reaction with sulfur vapor. Scanning electron microscopy, X-ray photoemission spectroscopy, and spectroscopic ellipsometry characterization reveals that the optimal morphology corresponds to a slightly porous AgS film. We demonstrate that the Ag/AgS μ-RE can be operated in and cycled through a wide variety of polar organic solvents, including common protic solvents (EtOH), aprotic solvents (ACN, DMSO, NMP, DMF) and ionic liquids (EMIM-TFSI, BMP-TFSI), with short equilibration time (tens of seconds) and little drift (<20 mV), without requiring encapsulation, protective liquid junctions, nor special conditioning. A redox potential of 0.54 ± 0.02 V was obtained for ferrocene in acetonitrile, which places this RE at 0.08 V Ag/AgCl. We have also successfully embedded the electrode inside the CR2032 coin cell to perform cyclic voltammetry of battery materials. These results underpin the suitability of this simple micro-reference electrode for a wide variety of electrochemical measurements in demanding and/or miniaturized environments.

中文翻译：

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可靠的非封装 Ag/Ag2S 微参比电极，适用于电池研究和有机介质中的其他应用

可靠的电化学测量取决于具有明确电位的稳健参比电极 (RE) 的可用性。虽然许多可靠的 RE 是已知的，但它们不适用于某些要求较高的介质（例如离子液体），也不适用于狭小的密闭空间。在这里，我们描述了一种简单而坚固的 Ag/AgS 微参比电极 (μ-RE) 的制造，其中通过与硫蒸气的等温反应形成微米厚的 AgS 层。扫描电子显微镜、X 射线光电子能谱和椭圆偏振光谱表征表明，最佳形态对应于微孔的 AgS 薄膜。我们证明Ag/AgS μ-RE可以在多种极性有机溶剂中操作和循环，包括常见的质子溶剂（EtOH）、非质子溶剂（ACN、DMSO、NMP、DMF）和离子液体（EMIM- TFSI、BMP-TFSI），平衡时间短（几十秒），漂移小（<20 mV），无需封装、保护液接界，也不需要特殊调节。二茂铁在乙腈中的氧化还原电位为 0.54 ± 0.02 V，这使得该 RE 的 Ag/AgCl 为 0.08 V。我们还成功地将电极嵌入 CR2032 纽扣电池内，以对电池材料进行循环伏安法。这些结果证明了这种简单的微参比电极适用于要求苛刻和/或小型化环境中的各种电化学测量。