Potential-dependent reorientation of water molecules at an electrode/electrolyte interface studied by surface-enhanced infrared absorption spectroscopy
Potential-dependent reorientation of water molecules at an electrode/electrolyte interface studied by surface-enhanced infrared absorption spectroscopy
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DOI：
10.1021/jp953636z
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发表时间：
1996-06-20
影响因子：
--
通讯作者：
Osawa, M
中科院分区：
文献类型：
--
作者：
Ataka, K;Yotsuyanagi, T;Osawa, M
用表面增强红外吸收光谱原位研究了高氯酸中高度有序的Au(111)电极表面水分子的结构和取向随外加电势的变化。这项新开发的红外光谱技术能够以非常高的灵敏度观察电极/电解液界面，而不会受到主体溶液的干扰。界面水的光谱与体水的光谱有很大的不同，在电极零电荷(PZC)附近和PZC正0.3V附近的峰频率和带宽有很大的变化。界面水分子在PZC以下形成弱氢键，在PZC略高于PZC时形成强氢键的冰状结构。由于高氯酸根离子的特殊吸附，类冰结构在更正的电位下被破坏，其中一个羟基部分水是非氢键的，另一个羟基部分是氢键连接到另一个水分子上。水的基模强度也是外加电势的强函数。它们在PZC附近非常弱，并随着正负方向的势能变化而增加。这些结果可以用表面电荷由负到正时水分子由氧向上向氧向下的电势依赖的重新取向来解释，并讨论了氢离子和高氯酸盐离子在金表面的吸附。
The structure and orientation of water molecules at a highly ordered Au(111) electrode surface in perchloric acid have been investigated in-situ as a function of applied potential by means of surface-enhanced infrared absorption spectroscopy. This newly developed infrared spectroscopy technique enables the observation of the electrode/electrolyte interface at a very high sensitivity without interference from the bulk solution. The spectrum of the interfacial water significantly differs from that of bulk water and drastically changes in peak frequencies and band widths around the potential of zero charge (pzc) of the electrode and at about 0.3 V positive from the pzc. The interfacial water molecules are weakly hydrogen-bonded at potentials below the pzc and form a strongly hydrogen-bonded ice-like structure at potentials slightly above the pzc. The ice-like structure is broken at more positive potentials due to the specific adsorption of perchlorate ion, where one OH moiety of water is non-hydrogen-bonded and the other OH moiety is hydrogen-bonded to another water molecule. The intensities of the fundamental modes of water are also a strong function of applied potential. They are very weak around the pzc and increase as the potential changes in both positive and negative directions. These results are explained in terms of the potential-dependent reorientation of water molecules from oxygen-up to oxygen-down as the surface charge changes from negative to positive, The adsorption of hydronium and perchlorate ions on gold is also discussed.