Synthesis of Active and Stable Platinum/ Ionic Liquid/ Carbon Nanotube Electrocatalysts for Oxidation of Methanol

• Main Authors: Guan-Lin Lin, 林冠霖
• Other Authors: Huan-Tsung Chang
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/50733714355362149861

碩士 === 國立臺灣大學 === 化學研究所 === 102 === Platinum (Pt) nanoparticles (NPs) on carbon nanotubes (CNTs) supports from PtCl62– ions through a facile ionic liquid (IL)-assisted method using ethylene glycol as a reducing agent has been developed and used for methanol oxidation. 1-Butyl-3-methylimidazolium (BMIM) with four different counter ions (PF6-, Cl-, Br-, and I-) have been tested for the preparation of Pt/IL/CNT nanohybrids, showing the counter ions of the ILs play an important role in the formation of small sizes of Pt NPs on the CNT supports. Only [BMIM][PF6] and [BMIM][Cl] allow reproducible preparation of Pt/IL/CNT nanohybrids, with average diameters of 2.8 ± 0.3 and 2.6 ± 0.2 nm for Pt NPs, respectively. The IL molecules adsorbed on the surfaces of CNTs interact with PtCl62– ions prior to their reduction and then stabilize the as-formed Pt NPs, leading to the formation of monodispersed and stable Pt NPs. The electroactive surface areas of as-prepared Pt/[BMIM][PF6]/CNT, Pt/[BMIM][Cl]/CNT, Pt/CNT nanohybrids, and commercial Pt/C NPs electrodes are 62.8, 101.5, 78.3, and 87.4 m2 g-1, respectively. The Pt/[BMIM][Cl]/CNT nanohybrid-modified electrodes provide higher catalytic activity (251.0 A g–1) toward methanol oxidation at a negative onset potential of -0.60 V (vs. Ag/AgCl) than commercial Pt/C-modified ones do (133.5 A g–1) at -0.46 V. Among the tested electrodes, the Pt/[BMIM][Cl]/CNT electrode provides the highest ratio (4.52) of forward/reverse oxidation current peak, revealing an efficient oxidation of methanol and a little accumulation of carbonaceous residues at the catalyst surface. The Pt/[BMIM][Cl]/CNT electrode is stable after sweeping at least for 20,000 s. With advantages of high electrochemical activity, stability, and cost effectiveness, the Pt/[BMIM][Cl]/CNT nanohybrids hold great potential as an efficient anode catalyst for direct methanol fuel cells.