Performance Study Of PtRu Catalysts Supported On Thiolated Carbon Nanotubes

Fuel cell is one of the energy conversion devices which is accepted as a potentialsubstitute for traditional energy supplying devices, for it has many obvious advantages,such as high energy conversion efficiency, rich supply, environment friendly and so on.Direct methanol fuel cells （DMFC） attract much attention from people for its lowoperating temperature, easy transportation and high specific power. Although DMFChas many excellent features, low stability and high oxidation potential need to beimproved before commercializing operation. Pt/C is also acted as the catalysts for theanode of DMFC. On the one hand, the oxidation potential of the fuel is so high thatDMFCs export low power; on the other hand, the catalyst is easy poisoned by theintermediate of the fuels.A novel thiolated CNTs （SH-CNTs） support was prepared by a home-made method.That is, the thiol groups are directly linked on the CNTs surface instead of viamercaptans, e.g.CNTs-C₆H₆CH₂-SH as reported previously. PtRu/SH-CNTs were alsosynthesized by the traditional impregnation method. The property of PtRu/SH-CNTscatalyst was evaluated by using CV, LSV, XRD, TEM and XPS. The TEM and CVresults show that the SH-CNTs achieve high PtRu dispersion and ensure the highactivity of the catalyst. LSV tests demonstrate that the oxidation potential of CO ofPtRu/SH-CNTs compared with PtRu/COOH-CNTs positively shift about0.026V, andthe same thing that the oxidation potential of CO positively shift about0.024V happento between Pt/SH-CNTs and Pt/COOH-CNTs; to the contrary, the oxidation potential ofCH3OH of PtRu/SH-CNTs compared with PtRu/COOH-CNTs negatively shift about0.037V, and the same thing that the oxidation potential of CH3OH negatively shiftabout0.034V happen to between Pt/SH-CNTs and Pt/COOH-CNTs. XRD tests displaythat the of PtRu/SH-CNTs and PtRu/COOH-CNTs which both synthesized by thetraditional impregnation method have the same highly alloying degree. That means thedifferences of the activity between PtRu/SH-CNTs and PtRu/COOH-CNTs have norelationship with the alloying degree. XPS reveal that the–SH group equally alter theelectronic structure between PtRu and support, which is the reason why Pt/SH-CNTsand PtRu/SH-CNTs hinders the oxidation of CO, but helps to promote the oxidation ofCH3OH.