CeO_2修饰炭载体负载PdPt二元合金催化剂及其在甲酸氧化电催化中的应用

用CeO2修饰炭粉做载体,使用有机溶胶法还原PdPt二元合金的方法制备了一系列PdPt/CeO2-C催化剂.借助电化学测试,探讨催化剂中不同Pd与Pt原子比例的PdPt二元合金和不同含量的CeO2对于甲酸电氧化催化活性的影响.不断减少PdPt合金中Pt的比例可以促使甲酸氧化的起始电位前移,当Pd：Pt=15：1时氧化电流出现极值;同时,随着催化剂中CeO2含量的增加,催化剂对于HCOOH氧化的电流密度增加,当含量为15%时达到最大值.相对于Pd/C催化剂,在Pd15Pt1/15CeO2-C催化剂表面的甲酸氧化反应起始电位负移至少0.1V,氧化的电流密度提高60%以上.结合X射线衍射（XRD）,X射线光电子能谱（XPS）,透射电镜（TEM）和热重（TG）等测试数据可以发现,当极少量的Pt与Pd形成合金,Pt与Pd之间产生电子效应,使得合金表面HCOOH氧化的过电位降低;而CeO2的添加不仅有助于PdPt二元合金的分散,更有可能改变甲酸在PdPt表面的氧化反应路径,发挥双功能机理.

Enhanced electro-oxidation of formic acid by PdPt bimetallic catalyst with CeO2-modified carbon support

PdPt bimetallic catalyst that employs CeO2-modified carbon black as support is prepared using an organic colloidal method.It shows excellent performance toward the anodic oxidation of formic acid.The effects of both Pd to Pt ratio and CeO2 content are investigated.The optimal Pd to Pt atomic ratio is 15,indicating that a slight addition of Pt could significantly enhance the catalyst＇s activity.When CeO2 content in the catalyst reaches as high as ～15 wt%,the catalyst shows the best activity.Adding CeO2 not only enhance catalytic activity of multiple catalysts,but also may change the mechanism of its catalysis toward the anodic oxidation of formic acid.Among all as-prepared PdPt/CeO2-C electrocatalysts,Pd15Pt1/15CeO2-C exhibited 60% higher activity than Pd/C,and had a negative shift in onset potential of more than 0.1 V.The catalyst was characterized by XRD,XPS,TG and TEM,and the interactions between the components are revealed and discussed.