三维多孔结构Pt-Ag气凝胶的制备及电催化氧还原反应性能

Synthesis of Three-dimensional Pt-Ag Aerogels and Their Electrocatalytic Performance Toward Oxygen Reduction Reaction

采用化学还原法及水热法制备了具有树枝状结构的铂-银气凝胶,并对其进行酸碱刻蚀再处理获得刻蚀后的铂-银气凝胶催化剂.利用X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等表征了铂-银气凝胶的结构、组成及微观形貌.利用循环伏安法(CV)和线性扫描伏安法(LSV)测试了催化剂对氧还原反应(ORR)的电催化活性和稳定性.结果表明,刻蚀后的Pt-Ag气凝胶具有优异的ORR活性,在0.9 V处,刻蚀后Pt-Ag气凝胶的质量比活性和面积比活性分别为166.3 m A/mgPt和0.295 m A/cm^2,分别是商业铂/碳催化剂(20%Pt/C)的2.0倍和1.8倍.该催化剂还具有优异的稳定性,循环5000周后,动力学催化质量比活性和面积比活性分别只降低了6.1%和9.1%,远小于商业Pt/C的35%和52.1%.

The etched-platinum-silver aerogel（ e-Pt-Ag gel） electrocatalysts with dendritic morphology were synthesized by chemical reduction and hydrothermal method,in which silver nanoparticles were removed by acid-and alkali-etching. X-ray diffraction（ XRD）,scanning electronic microscopy（ SEM） and transmission electron microscopy（ TEM） were employed to characterize the composition,structure and morphology of e-Pt-Ag gel. The activity and stability of the catalysts for oxygen reduction reaction（ ORR） were studied by cyclic voltammetry（ CV） and linear sweeping voltammetry（ LSV） methods. The results show that the e-Pt-Ag gel exhibits excellent ORR performance and favorable durability. In detail,the mass and specific activities of e-Pt-Ag gel at 0. 9 V are 166. 3 m A/mgPtand 0. 295 m A/cm2,respectively,which are 2. 0 and 1. 8 times that of the commercial Pt/C catalyst[84. 9 m A/mgPtand 0. 163 m A/cm2]. Furthermore,the mass and space activities of the e-Pt-Ag gel only decay 6. 1% and 9. 1%,respectively,after 5000 electrochemical cycles,showing higher durability of the e-Pt-Ag gel compared with Pt/C（ 35%,52. 1%）.