Structures and charging of α-alumina (0001)/water interfaces studied by sum-frequency vibrational spectroscopy
Structures and charging of α-alumina (0001)/water interfaces studied by sum-frequency vibrational spectroscopy
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DOI：
10.1021/ja8011116
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发表时间：
2008-06-18
影响因子：
15
通讯作者：
Shen, Y. Ron
中科院分区：
文献类型：
--
作者：
Zhang, Luning;Tian, Chuanshan;Shen, Y. Ron
用OH伸缩区的和频振动光谱研究了不同pH值下水/α-Al（2）O（3）（0001）界面的结构。观察到的光谱表明，质子化和去质子化的氧化铝表面占主导地位，在低和高pH值，分别与界面带正电荷和负电荷。零电荷点（pzc）出现在pH值约为6.3，这是接近从流动电位和二次谐波产生研究获得的值。它明显低于氧化铝粉末的pzc。结果可以从水/α-Al（2）O（3）（0001）界面质子化和去质子化的pK值来理解。发现无定形氧化铝的pzc与粉末氧化铝的pzc相似。
Sum-frequency vibrational spectroscopy in the OH stretch region was employed to study structures of water/alpha-Al(2)O(3) (0001) interfaces at different pH values. Observed spectra indicate that protonation and deprotonation of the alumina surface dominate at low and high pH, respectively, with the interface positively and negatively charged accordingly. The point of zero charge (pzc) appears at pH approximate to 6.3, which is close to the values obtained from streaming potential and second-harmonic generation studies. It is significantly lower than the pzc of alumina powder. The result can be understood from the pK values of protonation and deprotonation at the water/alpha-Al(2)O(3) (0001) interface. The pzc of amorphous alumina was found to be similar to that of powder alumina.