Influence of Supporting Materials on Catalytic Activities of Gold Nanoparticles as CO-Tolerant Catalysts in DMFC

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Gold nanoparticles supported on Pt-Sn/C and Pt/C (nano-Au/Pt-Sn/C and nano-Au/Pt/C, respectively) were prepared by the gas-phase grafting method and their catalytic activities for methanol oxidation were evaluated by steady-state polarization measurement. X-ray diffraction measurement revealed that gold nanoparticles had a diameter of ca. 4 nm, and X-ray photoelectron spectroscopy revealed that gold nanoparticles deposited on Pt-Sn/C and Pt/C were in the zero-oxidation state. Electrochemical measurements performed in an aqueous solution of 1 M (M=mol dm⁻³) HClO₄ and 1 M CH₃OH demonstrated that the addition of gold nanoparticles to Pt-Sn/C catalyst gave higher catalytic activities for methanol oxidation than Pt-Sn/C catalyst without gold nanoparticles. In contrast, nano-Au/Pt/C and Pt/C showed almost identical catalytic activities. These results showed that the catalytic activities of gold nanoparticles were influenced by the supporting materials.