采用X射线能量色散谱(EDS)、X射线衍射(XRD)、拉曼光谱和电化学等技术研究了直接甲酸燃料电池(DFAFC)中Vulcan XC-72碳黑载Ir(Ir/XC)和大孔碳载Ir(Ir/MC)催化剂对氧还原的电催化性能和抗甲酸能力.发现Ir/MC催化剂对氧还原的电催化性能优于Ir/XC催化剂,氧起始还原电位比在Ir/XC催化剂上正移0.1 V,极限电流密度比在Ir/XC催化剂上大30%左右.由于在Ir/MC和Ir/XC催化剂中Ir粒子的平均粒径和结晶度相似,因此,两种催化剂的性能差别可归结于与XC相比MC有较大的孔径和孔率及较高的石墨化程度,这说明MC是一种比XC更好的催化剂碳载体.另外,两种催化剂都有很好的抗甲酸能力.
The electrocatalytic performance and formic acid tolerance ability of the Vulcan XC-72 carbon black supported Ir(Ir/XC) catalyst and the macropore carbon supported Ir(Ir/MC) catalyst in the direct formic acid fuel cell were investigated by energy dispersive spectroscopy(EDS),X-ray diffraction(XRD) spectroscopy,Raman spectroscopy and electrochemical technique.It is found that the electrocatalytic performance of the Ir/MC catalyst for the oxygen reduction is better than that of the Ir/XC catalyst.The onset reduction potential of oxygen at the Ir/MC catalyst is 0.1 V more positive than that at the Ir/XC catalyst.The limiting current density of the oxygen reduction at the Ir/MC catalyst is 30% larger than that at the Ir/XC catalyst.This could be only attributed to the large pore diameter and porosity as well as high graphitization extent because the average diameters and relative crystallinity of the two catalysts are similar.In addition,both catalysts have good formic acid tolerance ability.Therefore,MC is a better carbon carrier of the catalyst than XC.