Cai Yu, Anderson Alfred B
Department of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106, USA.
J Phys Chem B. 2005 Apr 21;109(15):7557-63. doi: 10.1021/jp0458102.
Two redox reactions on platinum electrodes in base, the formation of underpotential deposited hydrogen, forming a Pt-H bond, and the electro-oxidation of water, forming a Pt-OH bond, were studied by two methods. The first applies a linear relationship between reaction energy in solution and standard reversible potential, an approach recently used in this lab to predict the formation potential of the surface-bonded species. This method depends on the availability of accurate surface adsorption bond strengths from measurement or theory and can be applied in two formats, the empirical model and the linear correlation model. The second method treats the reaction within the so-called double-layer model where reactants and products on the surface are well defined and are experiencing the influence of the electrolyte. When this approach is used, two coordination shells of hydrogen bonded water molecules are found necessary to sufficiently stabilize the hydroxide ion in this model, unlike acid for which past work showed only one shell around the hydronium ion is needed. The calculated reversible potentials for both reactions by the empirical and linear correlation models are in good agreement with the experimental onset potentials observed in cyclic voltammetry measurements for Pt(111) surface electrodes when empirical or accurately calculated H, OH, and H(2)O adsorption energies are used. The double layer models for these reactions also yield satisfactory results, and it is concluded that the models should be useful for studying electron-transfer reactions in base, as has already been done for forming Pt-H and Pt-OH in acid solution.
欠电位沉积氢的形成（形成Pt - H键）以及水的电氧化（形成Pt - OH键）。第一种方法利用溶液中反应能量与标准可逆电位之间的线性关系，这是本实验室最近用于预测表面键合物种形成电位的一种方法。该方法依赖于通过测量或理论获得的准确表面吸附键强度，并且可以以两种形式应用，即经验模型和线性相关模型。第二种方法在所谓的双层模型中处理反应，其中表面上的反应物和产物定义明确，并受到电解质的影响。使用这种方法时，发现与酸不同（过去的研究表明在水合氢离子周围只需要一个氢键水分子壳层），需要两个氢键水分子的配位壳层才能在该模型中充分稳定氢氧根离子。当使用经验或精确计算的H、OH和H₂O吸附能时，通过经验模型和线性相关模型计算得到的两个反应的可逆电位与在Pt(111)表面电极的循环伏安测量中观察到的实验起始电位吻合良好。这些反应的双层模型也产生了令人满意的结果，并且得出结论，这些模型对于研究碱性条件下的电子转移反应应该是有用的，就像已经在酸性溶液中研究形成Pt - H和Pt - OH时所做的那样。
