Instituto de Electroquímica, Universidad de Alicante. Apdo. 99, E-03080, Alicante, Spain.
Phys Chem Chem Phys. 2010 Aug 21;12(31):8822-31. doi: 10.1039/b925472b. Epub 2010 Jun 10.
Pulsed voltammetry has been used to study formic acid oxidation on platinum stepped surfaces to determine the kinetics of the reaction and the role of the surface structure in the reactivity. From the current transients at different potentials, the intrinsic activity of the electrode through the active intermediate reaction path (j(theta = 0)), as well as the rate constant for the CO formation (k(ads)) have been calculated. The kinetics for formic acid oxidation through the active intermediate reaction path is strongly dependent on the surface structure of the electrode, with the highest activity found for the Pt(100) surface. The presence of steps, both on (100) and (111) terraces, does not increase the activity of these surfaces. CO formation only takes place in a narrow potential window very close to the local potential of zero total charge. The extrapolation of the results obtained with stepped surfaces with (111) terraces to zero step density indicates that CO formation should not occur on an ideal Pt(111) electrode. Additionally, the analysis of the Tafel slopes obtained for the different electrodes suggests that the oxidation of formic acid is strongly affected by the presence of adsorbed anions, hydrogen and water.
脉冲伏安法已被用于研究在铂阶跃表面上甲酸的氧化，以确定反应的动力学和表面结构在反应性中的作用。从不同电位下的电流瞬变，可以通过活性中间体反应路径（j（θ=0））计算电极的本征活性，以及 CO 形成的速率常数（k（ads））。通过活性中间体反应路径的甲酸氧化动力学强烈依赖于电极的表面结构，在 Pt（100）表面上发现了最高的活性。在（100）和（111）平台上都存在台阶，并不会增加这些表面的活性。CO 的形成仅发生在非常接近总电荷零局部电位的狭窄电位窗口内。用具有（111）平台的阶跃表面获得的结果外推到零阶密度表明，CO 的形成不应该发生在理想的 Pt（111）电极上。此外，对不同电极获得的塔菲尔斜率的分析表明，甲酸的氧化强烈受吸附阴离子、氢和水的存在的影响。
