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.