Effect of Step Density and Orientation on the Apparent pH Dependence of Hydrogen and Hydroxide Adsorption on Stepped Platinum Surfaces.
Effect of Step Density and Orientation on the Apparent pH Dependence of Hydrogen and Hydroxide Adsorption on Stepped Platinum Surfaces.
复制标题
DOI：
10.1021/acs.jpcc.8b03660
复制
发表时间：
2018-07-26
期刊：
影响因子：
--
通讯作者：
Koper MTM
中科院分区：
文献类型：
--
作者：
McCrum IT;Chen X;Schwarz KA;Janik MJ;Koper MTM
通过计算和实验，在较宽的 pH 窗口 (1–13) 内阐明了碱金属阳离子（Li+、Na+、K+ 和 Cs+）对 Pt(554) 和 Pt(533) 阶跃相关伏安峰的非能斯特 pH 变化的影响。结合我们之前报道的 Pt(553) 研究，发现阶跃诱导峰的非能斯特 pH 值变化与阶跃密度和阶跃方向无关。在我们之前的工作中，我们将尖峰解释为由于吸附的氢和羟基之间沿台阶的交换以及碱金属阳离子的吸附及其随后对羟基吸附的减弱而导致的非能斯特位移。我们的密度泛函理论结果支持 Pt(533) 上的相同机制，并很好地捕捉了碱金属阳离子特性和碱金属阳离子覆盖度的影响，其中增加电解质 pH 和阳离子浓度会导致阳离子覆盖度增加，并对氢氧化物吸附产生更大的削弱作用。这项工作为这些效应的机制描绘了一致的图景，扩展了我们对电极/电解质界面的基本理解以及通过电解质成分控制氢和羟基吸附热力学的实际能力，这对于提高燃料电池和电解槽的性能非常重要。
The effect of the alkali-metal cation (Li+, Na+, K+, and Cs+) on the non-Nernstian pH shift of the Pt(554) and Pt(533) step-associated voltammetric peak is elucidated over a wide pH window (1–13), through computation and experiment. In conjunction with our previously reported study on Pt(553), the non-Nernstian pH shift of the step-induced peak is found to be independent of the step density and the step orientation. In our prior work, we explained the sharp peak as due to the exchange between adsorbed hydrogen and hydroxyl along the step and the non-Nernstian shift as a result of the adsorption of an alkali-metal cation and its subsequent weakening of hydroxyl adsorption. Our density functional theory results support this same mechanism on Pt(533) and capture the effect of alkali-metal cation identity and alkali cation coverage well, where increasing electrolyte pH and cation concentration leads to increased cation coverage and a greater weakening effect on hydroxide adsorption. This work paints a consistent picture for the mechanism of these effects, expanding our fundamental understanding of the electrode/electrolyte interface and practical ability to control hydrogen and hydroxyl adsorption thermodynamics via the electrolyte composition, important for improving fuel cell and electrolyzer performance.
登录
查看更多内容
影响因子：
4.4
作者：
Kolb, Manuel J.;Calle-Vallejo, Federico;Koper, Marc T. M.
通讯作者：
Koper, Marc T. M.
影响因子：
3.7
作者：
Kresse, G;Furthmuller, J
通讯作者：
Furthmuller, J
影响因子：
3.7
作者：
MONKHORST, HJ;PACK, JD
通讯作者：
PACK, JD
影响因子：
4.5
作者：
CLAVILIER, J;ARMAND, D;PETIT, M
通讯作者：
PETIT, M
影响因子：
4
作者：
McCrum, Ian T.;Janik, Michael J.
通讯作者：
Janik, Michael J.