Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
J Am Chem Soc. 2010 Oct 13;132(40):14036-8. doi: 10.1021/ja106618z.
We present the first broadband sum-frequency generation (SFG) spectra of adlayers from sulfuric acid solutions on Pt(111) surfaces and reveal surface transformations of (bi)sulfate anions in unprecedented detail. SFG amplitudes, bandwidth, and electrochemical Stark tuning of (bi)sulfate vibrational bands centered at 1250-1290 cm(-1) strongly depend on the applied potential and are correlated with prominent voltammetric features. (Bi)sulfate adlayers on Pt(111) are important model systems for weak, specific adsorption of anions on catalytically active surfaces. Although the existence of surface transformations on Pt(111) in dilute H(2)SO(4) solutions has been established by previous studies, so far they have not been observed with surface vibrational spectroscopy. Our results confirm previous reports of a surface transformation at 0.21 V and provide new information on a second transformation at 0.5 V due to surface hydroxyl formation and rearrangement of the electric double layer.
我们展示了硫酸溶液在 Pt(111)表面上的吸附层的首个宽带和频发生（SFG）光谱，并以前所未有的细节揭示了（双）硫酸盐阴离子在表面的转化。在 1250-1290 cm(-1) 处的（双）硫酸盐振动带的 SFG 幅度、带宽和电化学斯塔克调谐强烈依赖于所施加的电势，并与显著的伏安特征相关。Pt(111)上的（双）硫酸盐吸附层是研究阴离子在催化活性表面上弱、特异吸附的重要模型体系。尽管先前的研究已经证实了在稀 H(2)SO(4)溶液中 Pt(111)表面的转化的存在，但迄今为止，它们尚未通过表面振动光谱观察到。我们的结果证实了先前关于在 0.21 V 处的表面转化的报告，并提供了由于表面羟基形成和双电层重排而在 0.5 V 处的第二个转化的新信息。
