Protic ionic liquids (PILs) are ionic liquids that are formed by proton transfer from Brønsted acids to Brønsted bases, and which are being proposed for use in a wide range of electrochemical devices. In this contribution, we describe electrolysis of the PIL diethylmethylammonium trifluoromethanesulfonate at Pd, Pt, and Au electrodes in an ultra-high vacuum chamber connected to a mass spectrometer. At potentials negative of about −0.8 V vs. Pd/H, reduction of the PIL cations occurs, liberating H₂. Positive of about 2.2 V vs. Pd/H, electrooxidation of the PIL anions occurs, resulting in the detection of a number of fragments of the trifluoromethanesulfonate ions using the mass spectrometer. Notably, electrooxidation of the PIL anions occurs at the same potential, regardless of whether Pt, Au, or Pd is used as the electrode. In contrast, electrooxidation of water in the PIL occurs at different potentials in the PIL as the electrode composition changes. These results show that the electrochemical window of the PIL is independent of the electrode composition, but if water is present in the liquid, this independence is masked by the electrolysis of water.

质子性离子液体（PIL）是通过将质子从布朗斯台德酸转移到布朗斯台德碱而形成的离子液体，并且已提出将其用于各种电化学装置中。在这项贡献中，我们描述了在连接到质谱仪的超高真空室内，Pd，Pt和Au电极上PIL二乙基甲基三氟甲磺酸铵的电解。在相对于Pd / H约-0.8 V的负电势下，PIL阳离子发生还原，释放出H ₂。正约2.2的V对比在Pd / H中，发生PIL阴离子的电氧化，从而导致使用质谱仪检测到许多三氟甲磺酸根离子的碎片。值得注意的是，无论是否将Pt，Au或Pd用作电极，PIL阴离子的电氧化都会在相同的电势下发生。相反，随着电极组成的改变，PIL中水的电氧化在PIL中的不同电势处发生。这些结果表明，PIL的电化学窗口与电极组成无关，但是如果液体中存在水，则这种独立性会被水的电解所掩盖。