Synthesis of sulfated ZrO2/MWCNT composites as new supports of Pt catalysts for direct methanol fuel cell application

Sulfated zirconia supported on multi-walled carbon nanotubes as new supports of Pt catalyst (Pt–S-ZrO2/MWCNT) was synthesized with aims to enhance electron and proton conductivity and also catalytic activity of Pt electrocatalyst in terms of larger concentrations of ionizable OH groups on surfaces. Fourier transform infrared spectroscopy analysis shows that the sample surfaces were modified with sulfate. Transmission electron microscopy results show that the Pt and sulfated ZrO2 particles dispersed relatively uniformly on the surface of the multi-walled carbon nanotube. X-ray diffraction shows that S-ZrO2 and Pt coexist in the Pt–S-ZrO2/MWCNT composites and S-ZrO2 has no effect on the crystalline lattice of Pt. Pt–S-ZrO2/MWCNT catalyst was evaluated in terms of the electrochemical activity for methanol electro-oxidation using cyclic voltammetry, steady-state polarization experiments and electrochemical impedance spectroscopy technique at room temperature. Pt–S-ZrO2/MWCNT catalyst show higher catalytic activity for methanol electro-oxidation compared with Pt catalyst on non-sulfated ZrO2/MWCNT support and commercial Pt/C (E-TEK).