UPD铅对甲酸在铂上电氧化的助催化功用的研究

应用电位扫描和电位-时间程序技术研究了在UPD铅不存在和存在的情况下,各种因素对甲酸在铂上和酸介质中电催化氧化的影响。结果表明,在甲酸的CV图上,阳极方向的第一氧化峰和阴极方向的氧化峰是由于同一的弱吸附中间物的氧化,而阳极方向的第二和第三氧化峰是由于两种不同的强吸附中间物的氧化。cps值的测定和电极表面宏观结构的影响等实验表明,这些吸附中间物在电极表面上都呈线性吸附,它们分别可能是单键吸附的HCOO_ad双键吸附的CO_ad和叁键吸附的COH_ad。据此可以推论,UPD铅的主要功用是一种电子效应。

Study on Promotion of UPD of Lead for Electro-Oxidation of Formic Acid on Platinum

Using potential sweep and potential time sequence techniques, we have studied the promotion of UPDof lead for the clcctrocatalytic oxidation of formic acid on platinum in HClO₄ aqueous solution. The results showed that the first oxidation peak in anodic direction and oxidation peak in cathodic direction in the cyclic vol-tammogram are due to the oxidation of the same intermediate which is adsorbed weekly and the second and the third anodic peaks in anodic direction are due to the oxidation of the two different intermediates which are adsorbed strongly. Furthermore, all these intermediates are the linear adsorption on platinum surface and they are probably single bonded species, HCOO_ab,, and multiple bonded species, CO_ab and COH_ab, respectively. Thus, the function of UPDof lead for the oxidation of formic acid is neither the third-body effect nor the decrease of hydrogen adsorption thus preventing the formation of poisoning species.The role of UPDof lead should be an electronic effect, that is, it acts by modifying adsorption property of platinum in such a way that the oxidation of intermediate HCOO_ab becomes easier.