Thermodynamic analysis of the temperature dependence of OH adsorption on Pt(111) and Pt(100) electrodes in acidic media in the absence of specific anion adsorption
Thermodynamic analysis of the temperature dependence of OH adsorption on Pt(111) and Pt(100) electrodes in acidic media in the absence of specific anion adsorption
复制标题
DOI：
10.1021/jp054948x
复制
发表时间：
2006-06-15
影响因子：
3.3
通讯作者：
Feliu, Juan M.
中科院分区：
文献类型：
--
作者：
Climent, Victor;Gomez, Roberto;Feliu, Juan M.
本文研究了温度对高氯酸介质中Pt（111）和Pt（100）电极上OH吸附伏安法的影响。从热力学分析的基础上的广义吸附等温线，Δ G度，Δ H度，和Δ S度值的吸附OH已被确定。在Pt（111）上，吸附焓在-265 ~-235 kJ mol（-1）之间，随着OH覆盖度的增加，吸附焓变小。这些值与气相中相同反应的实验数据和计算值相当吻合。OH在Pt（111）上的吸附熵为-200 J mol（-1）K（-1）（低覆盖度）~-110 J mol（-1）K（-1）（高覆盖度）。另一方面，羟基在Pt（100）上吸附的焓和熵对覆盖度变化不太敏感，其值为ca。Δ H度= -280 kJ mol（-1）和Δ S度= -180 J mol（-1）K-1。两个电极表面上的覆盖率的不同依赖性的三角洲S度强调的重要影响的基板对称性的流动性的吸附OH物种内的水网络直接连接到金属表面。
The effect of temperature on the voltammetric OH adsorption on Pt(111) and Pt(100) electrodes in perchloric acid media has been studied. From a thermodynamic analysis based on a generalized adsorption isotherm, Delta G degrees, Delta H degrees, and Delta S degrees values for the adsorption of OH have been determined. On Pt(111), the adsorption enthalpy ranges between -265 and -235 kJ mol(-1), becoming less exothermic as the OH coverage increases. These values are in reasonable agreement with experimental data and calculated values for the same reaction in gas phase. The adsorption entropy for OH adsorption on Pt(111) ranges from -200 J mol(-1) K-1 (low coverage) to -110 J mol(-1) K-1 (high coverage). On the other hand, the enthalpy and entropy of hydroxyl adsorption on Pt(100) are less sensitive to coverage variations, with values ca. Delta H degrees = -280 kJ mol(-1) and Delta S degrees = -180 J mol(-1) K-1. The different dependence of Delta S degrees with coverage on both electrode surfaces stresses the important effect of the substrate symmetry on the mobility of adsorbed OH species within the water network directly attached to the metal surface.