Activity of carbon-supported platinum nanoparticles toward methanol oxidation reaction : Role of metal precursor and a new surfactant, tert-octanethiol

Two groups of carbon-supported platinum nanoparticle catalysts have been prepared. In group I, catalysts I and II were prepared using PtCl4 and H2PtCl6 as starting materials and 1-hexanethiol, HSCH2CH2CH2CH2CH2CH3, as a surfactant. For group II, the same platinum complexes were used as starting materials (catalyst III from PtCl4, catalyst IV from H2PtCl6) and tert-octanethiol, HSC(CH3)2CH2CH2CH2CH2CH3, was used as a surfactant for the first time. It has been found that the group II catalysts are between ∼2 and ∼3.3 times more active toward methanol oxidation reaction compared to other prepared and commercial catalysts. Transmission electron microscopy shows that the platinum nanoparticles are homogeneously dispersed on the carbon support and exhibit a narrow size distribution; the average particle size was found to be 2 ± 0.4 and 3 ± 0.4 nm in diameter for group I and group II catalysts, respectively. X-ray diffractogram analysis indicates that the platinum nanoparticles have a face centered cubic structu...