Methanol electro-oxidation on Pt nanocatalysts prepared by atomic layer deposition

The present work adopts an atomic layer deposition (ALD) technique to synthesize highly-crystalline Pt nanoparticles onto carbon powders, offering superior catalytic activity toward methanol oxidation within the temperature range of 25-55 degrees C. Uniformly-dispersed Pt nanoparticles with an ultralow loading are coated over the carbon supports, served as catalyst materials for methanol electro-oxidation. Experimental results reveal that ALD-Pt catalyst offers not only an improved catalytic activity toward methanol oxidation but also superior CO tolerance, as compared to commercial Pt one. The decreased current ratio for direct to indirect pathway with an increase in temperature is found, referring to the kinetic limitations for the formation and oxidation of Pt-(CO)(ads) sites at high temperatures. Followed up Arrhenius-type behavior, small apparent activation energies (i.e., ca. 30.3 and 41.7 kJ mol(-1)) of ALD-Pt catalyst can be achieved for dehydrogenation of methanol (direct pathway) and oxidation of adsorbed CO species (indirect pathway) in methanol oxidation reaction. The low potential barrier on ALD-Pt catalyst is attributed to small particle size (i.e., average particle size of 2.1 nm) and oxidized Pt surface (i.e., native Pt-O* active sites) that efficiently enhance the catalytic activity and CO tolerance, respectively. As a result, this study examines the influence of temperature on catalytic activity and anti-poisoning performance on the ALD-Pt catalyst, in which the surface chemistry and structural motif is more efficient at electrochemically oxidizing methanol and improving the CO tolerance.