Murke Steffen, Chen Wanlin, Pezzotti Simone, Havenith Martina
Department of Physical Chemistry II, Ruhr University Bochum, D-44801 Bochum, Germany.
J Am Chem Soc. 2024 May 8;146(18):12423-12430. doi: 10.1021/jacs.3c13633. Epub 2024 Apr 10.
Acid-base reactions are ubiquitous in solution chemistry, as well as in electrochemistry. However, macroscopic concepts derived in solutions, such as p and pH, differ significantly at electrified metal-aqueous interfaces due to specific solvation and applied voltage. Here, we measure the p values of an amino acid, glycine, at a gold/water interface under a varying applied voltage by means of spectroscopic titration. With the help of simulations, we propose a general model to understand potential-dependent shifts in p values in terms of local hydrophobicity and electric fields. These parameters can be tuned by adjusting the metal surface and applied voltage, respectively, offering promising, but still unexplored, paths to regulate reactivity. Our results change the focus with respect to common interpretations based on, for example, apparent local pH effects and open interesting perspectives for electrochemical reaction steering.
酸碱反应在溶液化学以及电化学中无处不在。然而，由于特定的溶剂化作用和外加电压，溶液中衍生出的宏观概念，如p和pH，在带电的金属-水界面处有显著差异。在这里，我们通过光谱滴定法测量了在不同外加电压下金/水界面处氨基酸甘氨酸的p值。借助模拟，我们提出了一个通用模型，以根据局部疏水性和电场来理解p值的电位依赖性变化。这些参数可以分别通过调整金属表面和外加电压来调节，为调节反应性提供了有前景但仍未被探索的途径。我们的结果改变了基于例如表观局部pH效应的常见解释的关注点，并为电化学反应控制开辟了有趣的新视角。
