大孔炭载Pd催化剂对甲酸氧化的电催化性能

Electrocatalytic Performance of Pd Catalyst Supported on Macropore Carbon for Oxidation of Formic Acid

用X射线能量色散谱(EDS)、X射线衍射(XRD)谱、拉曼光谱和电化学技术研究和比较了直接甲酸燃料电池(DFAFC)中Vulcan XC-72炭黑载Pd(Pd/XC)和大孔炭载Pd(Pd/MC)催化剂对甲酸氧化的电催化性能.循环伏安曲线测量表明甲酸在Pd/XC和Pd/MC催化剂电极上主要氧化峰的峰电位基本相同,在0.15V左右,但在Pd/MC催化剂电极上的峰电流密度比在Pd/XC催化剂上的大30%左右.计时电流曲线测量表明,在6000s时,在Pd/MC催化剂电极上的峰电流密度比在Pd/XC催化剂上的大38%左右,这些结果说明Pd/MC催化剂对甲酸氧化的电催化活性和稳定性要好于Pd/XC催化剂.由于Pd/MC和Pd/XC催化剂的Pd粒子平均粒径和相对结晶度相似,因此,Pd/MC催化剂电催化性能好的原因只能归结于MC大的孔径和高的石墨化程度引起的高电导率.

The electrocatalytic performances of a Vulcan XC-72 carbon black supported Pd （Pd/XC） catalyst and a macroporous carbon supported Pd （Pd/MC） catalyst for formic acid oxidation in a direct formic acid fuel cell were investigated and compared.This was carried out using X-ray energy dispersive spectroscopy （EDS）,X-ray diffraction （XRD） spectroscopy,Raman spectroscopy,and electrochemical techniques.The cyclic voltammograms indicate that the main peak potentials for the oxidation of formic acid at the Pd/XC and Pd/MC catalyst electrodes are similar and they are located at about 0.15 V.However,the peak current density of the Pd/MC catalyst electrode is about 30% larger than that of the Pd/XC catalyst electrode.The chronoamperometric curves indicate that the peak current density at the Pd/MC catalyst electrode at 6000 s is about 38% larger than that at the Pd/XC catalyst electrode.These results show that the electrocatalytic activity and stability of the Pd/MC catalyst for the oxidation of formic acid are better than those of the Pd/XC catalyst.Because the average size and relative crystallinity of the Pd particles in the two catalysts are similar,the reason for the better electrocatalytic performance of the Pd/MC catalyst could be only attributed to its larger pore diameter and higher conductivity because of its high extent of MC graphitization.