Rodríguez-López Margarita, Rodes Antonio, Herrero Enrique, Tuñón Paulino, Feliu Juan M, Aldaz Antonio, Carrasquillo Arnaldo
Pontifical Catholic University of Puerto Rico, Ponce, Puerto Rico.
Langmuir. 2009 Sep 1;25(17):10337-44. doi: 10.1021/la900771c.
The electrochemical reactivity of hydroquinone-derived adlayers (Q((ads))) is compared at basal Pt(hkl) single-crystal surfaces, revealing that the electrochemically controlled desorption of Q((ads)) is a highly selective surface reaction. At well-ordered Pt(111) single-crystal surfaces, classical electrochemical methods are combined with in situ SNIFTIRS measurements to demonstrate that the reductive desorption of Q((ads)) and their full oxidative readsorption can be achieved, even in the presence of hydroquinone solution (H(2)Q(aq)), by controlling the potential of Pt(111) electrodes. At well-ordered Pt(111) domains, the presence of vertically adsorbed molecules within the Q((ads)) adlayer is deduced from the spectroelectrochemical SNIFTIRS measurements. The desorption mechanism, detected voltammetrically at Pt(111) electrodes, is precluded at well-ordered Pt(110) and Pt(100) single-crystal electrodes immersed in hydroquinone-containing solutions, requiring the presence of well-ordered Pt(111) surface domains in order to be detected. In clean supporting electrolyte, the partial desorption of Q((ads)) layers may take place, but predominantly from minority surface imperfections at Pt(110) and Pt(100) via a different mechanism than at Pt(111) surface domains.
对苯二酚衍生吸附层（Q((ads))）在铂（hkl）基底单晶表面的电化学反应活性进行了比较，结果表明，Q((ads))的电化学控制脱附是一种高度选择性的表面反应。在有序的铂（111）单晶表面，经典电化学方法与原位表面增强红外光反射吸收光谱（SNIFTIRS）测量相结合，结果表明，即使存在对苯二酚溶液（H(2)Q(aq)），通过控制铂（111）电极的电位，也能实现Q((ads))的还原脱附及其完全氧化再吸附。在有序的铂（111）畴上，通过光谱电化学SNIFTIRS测量推断出Q((ads))吸附层内存在垂直吸附的分子。在浸入含对苯二酚溶液中的有序铂（110）和铂（100）单晶电极上，通过伏安法检测到的脱附机制不存在，需要存在有序的铂（111）表面畴才能被检测到。在纯净的支持电解质中，Q((ads))层可能会发生部分脱附，但主要是通过与铂（111）表面畴不同的机制，从铂（110）和铂（100）的少数表面缺陷处发生脱附。
