【摘要】 利用化学-电化学方法制备了Ag/Au/Pt复合催化剂.该催化剂以100 nm左右的Ag颗粒为基底,以化学方法沉积金再电沉积铂,这降低了贵金属Au和Pt的用量.通过SEM,EDX和XRD对样品进行表征,并测试对甲酸的电催化氧化性能.研究表明,当Pt∶Au原子数比小于1∶10时,主要表现为直接氧化,在较低的Pt负载量(0.71μg/cm2)情况下,Ag/Au/Pt复合催化剂对甲酸氧化的直接氧化峰电流密度达到最大.甲酸的电催化氧化稳定性实验表明,当Pt载量为0.05μg时,相对于最大峰电流密度,循环伏安扫描第100圈时甲酸氧化的直接氧化峰电流密度仅衰减了2.29%.同时CO氧化剥离实验表明,当Pt∶Au=1∶6时,Ag/Au/Pt复合催化剂对CO氧化峰电势最负,相对于纯Pt催化剂负移了大约0.13 V,表明该复合催化剂具有更好的抗CO毒化能力.更多还原

【Abstract】 Ag/Au/Pt composite catalyst has been fabricated by chemical and electrochemical methods.The catalyst is fabri-cated by the electrodeposition of 100 nm Ag nanoparticle,then Au is deposited by chemical reduction,and Pt is electrode-posited finally,the quantity of Au and Pt is reduced.The samples have been characterized by scanning electron microscopy(SEM),X-ray energy dispersive spectroscopy(EDX) and X-ray diffraction(XRD) techniques.In addition,the electrocata-lytic performance of composite electrode materials is measured by cyclic voltammetry(CV) towards formic acid oxidation.The results demonstrate that the as-prepared Ag/Au/Pt composite catalyst with low Pt loading(0.71 μg/cm2) shows much higher catalytic activity than that of the same amount of pure Pt catalyst towards formic acid electrooxidation,and the current density of direct oxidation for formic acid reaches 4541.42 mA/mg.On the other hand,the content of Pt has a significant influence on formic acid oxidation path.It is found that formic acid electrooxidation on the Ag/Au/Pt composite catalyst mainly follows the direct oxidation path only when the atomic ratio of Pt∶Au is less than 1∶10.The enhanced performance is mainly due to the increase of electrochemical active surface area(EASA) through CVs in H2SO4 solution.Moreover,the Ag/Au/Pt composite catalyst exhibits greater poisoning tolerance than that of pure Pt during formic acid electrooxidation,shown in the results of chronoamperometre(CA) measurement.The stability of composite catalyst is evaluated via recording the CV scans of 100 cycles of electrodes towards formic acid oxidation.At the 100th cycle,the current density of Ag/Au/Pt electrode just decreases 2.29%,which is far lower compared with the other electrodes.The CO stripping voltammogram in acid medium is recorded as well.The results show clearly that the CO stripping peak position of composite catalyst shifts negatively compared with that of the pure Pt catalyst in the mass.When the atomic ratio of Pt∶Au is 1∶6.0,the composite catalyst presents lowest peak potential for CO electrooxidation.更多还原