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

Abstract

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5x10-3MOl·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13.19x10-10MOl·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.

The present paper studies the kinetics of dissociative adsorption of formic acid on electrode of tetrahexa-hedral platinum nanocrystals (THH Pt NCs).In situ FTIR spectroscopic results demonstrated that HCOOH can beoxidized to CO2 at a low potential (-0.20 V(SCE)) on the THH Pt NCs electrode, and the chemical bonds inside for-mic acid molecule are broken to form adsorbed COL species.The kinetics of the dissociative adsorption of HCOOHwas quantitatively investigated by employing programmed potential step technique.It has been determined that, in5×10?3 mol·L-1 HCOOH + 0.1mol·L-1 H2SO4 solution, the maximal value of the average rate (υa max) of dissociativeadsorption of HCOOH on a commercial Pt/C catalyst electrode is 8.58×10-10 mol·cm-2·s-1, while on the THH Pt NCsthe υamax is 1.5 times larger than the υamax measured on Pt/C and reaches 13.19×10-10 mol·cm-2·s-1.The results haverevealed that the reactivity of the THH Pt NCs is much higher than that of the Pt/C catalysts.