Active and stable platinum/ionic liquid/carbon nanotube electrocatalysts for oxidation of methanol

Abstract

Platinum (Pt) nanoparticles (NPs) on carbon nanotubes (CNTs) have been prepared from PtCl 6 2− ions through a facile ionic liquid (IL)-assisted method and used for methanol oxidation. 1-Butyl-3-methylimidazolium (BMIM) with four different counter ions (PF 6 − , Cl − , Br − , and I − ) has been tested for the preparation of Pt/IL/CNT nanohybrids, showing the counter ions of ILs play an important role in the formation of small sizes of Pt NPs. Only [BMIM][PF 6 ] and [BMIM][Cl] allow reproducible preparation of Pt/IL/CNT nanohybrids. The electroactive surface areas of Pt/[BMIM][PF 6 ]/CNT, Pt/[BMIM][Cl]/CNT, Pt/CNT, and commercial Pt/C electrodes are 62.8, 101.5, 78.3, and 87.4 m 2 g −1 , respectively. The Pt/[BMIM][Cl]/CNT nanohybrid-modified electrodes provide higher catalytic activity (251.0 A g −1 ) at a negative onset potential of −0.60 V than commercial Pt/C-modified ones do (133.5 A g −1 ) at −0.46 V. The Pt/[BMIM][Cl]/CNT electrode provides the highest ratio (4.52) of forward/reverse oxidation current peak, revealing a little accumulation of carbonaceous residues.