Nanostructured Pd hydride microelectrodes: in situ monitoring of pH variations in a porous medium.
Nanostructured Pd hydride microelectrodes: in situ monitoring of pH variations in a porous medium.
复制标题
DOI：
10.1021/ac500310j
复制
发表时间：
2014-05
影响因子：
7.4
通讯作者：
M. Serrapede;G. Pesce;R. Ball;G. Denuault
中科院分区：
文献类型：
--
作者：
M. Serrapede;G. Pesce;R. Ball;G. Denuault
在这项研究中，我们报告了特殊的电位特性的pH微探针与纳米结构的钯氢化物微电极，并证明了它们的应用，通过监测pH值的变化所产生的反应局限在多孔介质中。他们的电位响应被发现是可重复的，稳定超过几个小时，但主要是能斯特在一个非常宽的pH值范围内，包括碱性条件高达pH值14。通过定期重新加载氢气以保持正确的氢化物组成，从而减轻校准的需要，证明了连续操作。通过检测纤维网内Ca（OH）2碳酸化过程中的pH瞬变来验证这些特性。实验pH值记录在原位与考虑的CO2分压的理论计算非常一致。结果还表明，电极是足够敏感，以区分球霰石和方解石，两种多晶型的碳酸钙的形成。这些纳米结构的微电极是唯一适合于在高碱性溶液中的pH值的测定，特别是那些在固体和多孔表面的界面反应所产生的，因此非常适合作为扫描电化学显微镜的pH传感器。
In this study we report the exceptional potentiometric properties of pH microprobes made with nanostructured palladium hydride microelectrodes and demonstrate their application by monitoring pH variations resulting from a reaction confined in a porous medium. Their potentiometric response was found to be reproducible and stable over several hours but primarily Nernstian over a remarkably wide pH range, including alkaline conditions up to pH 14. Continuous operation was demonstrated by reloading hydrogen at regular intervals to maintain the correct hydride composition thereby alleviating the need for calibration. These properties were validated by detecting pH transients during the carbonation of Ca(OH)2 within a fibrous mesh. Experimental pHs recorded in situ were in excellent agreement with theoretical calculations for the CO2 partial pressures considered. Results also showed that the electrodes were sufficiently sensitive to differentiate between the formation of vaterite and calcite, two polymorphs of CaCO3. These nanostructured microelectrodes are uniquely suited to the determination of pH in highly alkaline solutions, particularly those arising from interfacial reactions at solid and porous surfaces and are thus highly appropriate as pH sensing tips in scanning electrochemical microscopy.