二十四面体Pt纳米晶电极上甲酸解离吸附反应动力学研究

研究了甲酸在二十四面体Pt纳米晶（THHPtNCs）电极表面解离吸附反应过程.电化学原位红外反射光谱结果显示,甲酸在低电位（-0.20V（SCE））即可在THHPtNCs电极上氧化到CO2,同时发生分子内化学键断裂生成吸附态CO物种.运用程序电位阶跃暂态方法定量研究甲酸解离吸附反应动力学,测得5×10^-3mol·L^-1 HCOOH＋0.1mol·L^-1 H2SO4溶液中甲酸在THHPtNCs电极上解离吸附的最大平均速率υamax为13.19×10^-10mol·cm^-2·s^-1,是商品Pt/C催化剂电极上υamax的1.5倍.研究结果揭示了THHPtNCs的反应活性显著高于Pt/C催化剂.

Study of kinetics of dissociative adsorption of formic acid on electrode of tetrahexahedral platinum nanocrystals

The present paper studies the kinetics of dissociative adsorption of formic acid on electrode of tetrahexahedral platinum nanocrystals （THH Pt NCs）. In situ FTIR spectroscopic results demonstrated that HCOOH can be oxidized to COe at a low potential （-0.20 V（SCE）） on the THH Pt NCs electrode, and the chemical bonds inside formic acid molecule are broken to form adsorbed COt species. The kinetics of the dissociative adsorption of HCOOH was quantitatively investigated by employing programmed potential step technique. It has been determined that, in 5× 10^-3 mol·L^-1 HCOOH ＋ 0. 1 mol.L^-1 H2SO4 solution, the maximal value of the average rate （Va^max） of dissociative adsorption of HCOOH on a commercial Pt/C catalyst electrode is 8.58×10^-10 mol.cm^-2.s^-1, while on the THH Pt NCs the va^max is 1.5 times larger than the Va^max measured on Pt/C and reaches 13.19×10^-10 mol.cm^-2·s^-1. The results have revealed that the reactivity of the THH Pt NCs is much higher than that of the Pt/C catalysts.