Catalyst Activity Enhancement of PtRu/CB for Methanol Oxidation by Carbon Nanotube Doping

A hybrid support material for catalyst is proposed and studied in the paper. A small fraction of single-wall carbon nanotubes (SWCNTs) were added into commercial carbon black (CB)-supported PtRu electrocatalyst. Catalyst inks with different SWCNTs´ doping concentrations were prepared, characterized, and investigated for methanol electrooxidation using cyclic voltammetry. Compared with the control group (no SWCNTs´ doping), catalyst with a proper amount of SWCNTs´ doping has five times catalytic activity enhancement for methanol oxidation for the same amount of PtRu loading. Catalyst films with different SWCNTs´ doping concentrations were inspected with scanning electron microscope and transmission electron microscope. Results suggested that addition of a SWCNT into PtRu/CB altered the catalyst-supporting material from pure CB spheres to hybrid SWCNT-CB matrix and, therefore, significantly changed PtRu nanoparticles distribution, catalyst film morphology, and, consequently, the catalyst activity toward methanol oxidation. A proper fraction of SWCNTs will attract PtRu onto surrounding SWCNTs without causing aggregation, which improves the effective surface reaction area and catalyst activity for methanol oxidation. This hybrid catalyst-support matrix provides a solution to the challenging issue of catalyst dispersion and accessibility dilemma and is very promising as a highly efficient and cost-effective catalyst system.