Adsorption and Oxidation of Formic Acid on Smooth Platinum Electrodes in Perchloric Acid Solutions
Adsorption and Oxidation of Formic Acid on Smooth Platinum Electrodes in Perchloric Acid Solutions
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DOI：
10.1021/j100788a030
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发表时间：
1964-06
期刊：
影响因子：
--
通讯作者：
S. Brummer;A. C. Makrides
中科院分区：
文献类型：
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作者：
S. Brummer;A. C. Makrides
采用阳极、阴极计时电位法和恒电位法研究了甲酸在HC104溶液中光滑铂电极上的吸附和氧化。每个电位下的氧化速率被确定为电极制备、pH和甲酸浓度的函数。阳极预处理激活了HCOOH随后氧化的电极。然而，在任何给定电位下的氧化速率随着时间的推移而下降，因为一种干扰HCOOH氧化的物质的缓慢吸附。在一系列电位下测定了阻断物质的吸附动力学和吸附程度。当电位高于0.35 v时，平衡吸附量减小，当电位高于0.70 v时，平衡吸附量基本为零。HCOOH的氧化速率与自由表面、HCOOH浓度和ph呈正一级关系，在电位高于0.4 v时，氧化速率随电位升高呈Tafel型关系（斜率~ 60 mv.），但此后的氧化速率与电位无关。目前的平台不受扩散控制。提出了一种氧化机理，其中慢步是氢氧根的非电化学解离反应。
The adsorption and oxidation of formic acid on smooth platinum electrodes were studied in HC104 solutions by anodic and cathodic chronopotentiometry and by potentiostatic techniques. The oxidation rate at each potential was determined as a function of elec-trode preparation, pH, and formic acid concentration. Anodic pretreatment activates an electrode for the subsequent oxidation of HCOOH. However, the oxidation rate at any given potential declines with time because of the slow adsorption of a substance which inter-feres with the oxidation of HCOOH. The kinetics of adsorption and the extent of ad-sorption of the blocking substance were determined at a series of potentials. The equi-librium adsorption decreases with potential above 0.35 v. and is essentially zero at 0.70 v. The rate of oxidation of HCOOH is first order with respect to the free surface, the HCOOH concentration, and the pH. The oxidation rate increases with potential according to a Tafel type relation (slope~ 60 mv.) up topotentials of about 0.4 v., but the rate is independent of potential thereafter. The current plateau is not controlled by diffusion. A mechanism for oxidation is suggested in which the slow step is a nonelectrochemical dis-sociative reaction of HCOOH.