高等学校化学学报 ›› 2003, Vol. 24 ›› Issue (3): 501.

• 论文 • 上一篇    下一篇

酸性和碱性介质中甘氨酸解离吸附和氧化的EQCM研究

谷艳娟, 周志有, 陈声培, 甄春花, 孙世刚   

  1. 厦门大学固体表面物理化学国家重点实验室, 化学系, 物理化学研究所, 厦门 361005
  • 收稿日期:2001-11-25 出版日期:2003-03-24 发布日期:2003-03-24
  • 通讯作者: 孙世刚(1954年出生),男,博士,教授,博士导师,从事表面电化学与电催化研究.E-mail:sgsun@xmu.edu.cn E-mail:sgsun@xmu.edu.cn
  • 基金资助:

    国家自然科学基金(批准号:29973035,90206039);教育部骨干教师计划基金资助

An EQCM Study of Adsorption and Oxidation of Glycine at a Pt Electrode in Acid and Alkaline Solutions

GU Yan-Juan, ZHOU Zhi-You, CHEN Sheng-Pei, ZHEN Chun-Hua, SUN Shi-Gang   

  1. State Key Laboratory for Physical Chemistry of Solid Surfaces, Department of Chemistry, Institute of Physical Chemistry, Xiamen University, Xiamen 361005, China
  • Received:2001-11-25 Online:2003-03-24 Published:2003-03-24

摘要: 用电化学石英晶体微天平(EQCM)研究酸性和碱性介质中甘氨酸在Pt电极上的吸附和氧化过程.结果表明,甘氨酸的解离吸附和氧化行为与溶液的酸碱性密切相关.酸性溶液中甘氨酸吸附较弱,碱性溶液中则产生强吸附物,且当电位低于0V(vs.SCE)时可吸附于Pt电极表面.此外,碱性溶液中甘氨酸还表现出较高的电氧化活性.通过EQCM定量检测上述过程中Pt电极表面的质量变化,测定了不同电位区间(氢区、双电层区和氧区)每传递一个电子所对应的电极表面吸附物种的平均摩尔质量.

关键词: 甘氨酸, 电化学石英晶体微天平(EQCM), Pt电极, 吸附, 氧化

Abstract: Adsorption and oxidation of glycine at a Pt electrode were studied by using electrochemical quartz crystal microbalance(EQCM) in both acid and alkaline solutions. The results demonstrate that the behavior of adsorption and oxidation of glycine depends strongly on the acidity of solutions. The adsorption of glycine is weak in acid solution. However, glycine can be decomposed in alkaline solution to produce adsorbates that are stable on Pt surface below 0.0 V(vs. SCE). It has been revealed that the activity of glycine oxidation is higher in alkaline solutions than that in acid solutions. The surface mass change(Δm) and the average molar mass(M/n) of all adsorbates on Pt electrode surface per electron transferred in the above processes have been determined quantitatively through EQCM. An increase of 58.6 ng/cm2 in Δm was detected in acid solutions for the process of hydrogen desorption from -0.25 to 0.11 V(vs. SCE) at Pt electrode, which was ascribed to the replacement of adsorbed hydrogen by the adsorption of water molecules or/and glycine anions. The EQCM frequency change in the oxygen region(between 0.35 and 1.20 V) was mainly caused by the adsorption of oxygen, the oxidation of adsorbed species and the oxidation of glycine, which resulted in an increase of 43.4 ng/cm2 in the surface total mass change. This value is smaller than that(61.2 ng/cm2) acquired in a sulfuric acid solution free of glycine in the same potential region. In the case of alkaline solutions, the surface mass change of Pt electrode is related directly to the dissociative adsorption of glycine. When the upper limit of potential scan was set at 0.60 V, an increase in surface mass of 17.6 ng/cm2 in the hydrogen region and an increase in surface mass of 43.0 ng/cm2 in the oxygen region at Pt electrode have been determined.

Key words: Glycine, Electrochemical quartz crystal microbalance(EQCM), Platinum electrode, Adsorption, Oxidation

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