Pt/CeO2-CNTs和Pt/CNTs在H2SO4和NaOH中乙醇电氧化活性及循环稳定性研究

为考察pH和CeO2对Pt催化剂乙醇电氧化活性的影响,用循环伏安法比较了Pt/CNTs及Pt/CeO2-CNTs在NaOH和H2SO4介质中的电化学行为,表明催化剂在NaOH介质中活性高于在H2SO4中活性,Pt/CeO2-CNTs活性高于Pt/CNTs活性.因Pt催化剂上乙醇电氧化反应的tafel斜率接近,故活性不同可归于影响交换电流密度的OHad浓度的差别.NaOH中Pt表面OHad吸附起始电位和乙醇电氧化起始电位分别低于H2SO4中起始电位,表明OHad决定着Pt催化剂的乙醇电氧化活性.加速耐久性实验表明,CeO2可改善Pt/CNTs的循环稳定性,Pt/CeO2-CNTs和Pt/CNTs在H2SO4中稳定性优于在NaOH中稳定性.

The Ethanol Electro-oxidation Activity and Cycling Stability of Pt/CeO2-CNTs and Pt/CNTs in H2SO4 and NaOH

To investigate the effect of pH and CeO2 on ethanol electro-oxidation activity of Pt-based catalysts,Pt/CNTs and Pt/CeO2-CNTs were characterized by cyclic voltammetry（CV） sweeping in NaOH and H2SO4.The results showed that activity for Pt-based catalysts in NaOH was higher than that in H2SO4,and the activity for Pt/CeO2-CNTs was higher than that for Pt/CNTs.Since the tafel slopes of ethanol electro-oxidation on Pt-based catalysts were similar,it was deduced that the concentration of OHad,which influenced the exchange current density,determined the apparent activity.The lower onset potential for Pt-OH adsorption and ethanol electro-oxidation in NaOH than in H2SO4 supported the effects of OHad.Accelerated durability tests showed that CeO2 could improve the stabilities of Pt/CNTs.And Pt-based catalysts were more stable in H2SO4 than that in NaOH.