Methanol tolerant Pt₂CrCo catalysts supported on ordered mesoporous carbon for the cathode of DMFC

Graphitized ordered mesoporous carbon CMK-3-R8 supported Pt₂CrCo electrocatalysts were synthetized by the borohydride reduction method (BM) and then submitted to a reductive thermal treatment (TT) at 300, 500 and 700 °C with the aim to improve their catalytic activity toward the oxygen reduction reaction (ORR) and the methanol tolerance. Atomic composition and total metal loading were determined by energy dispersive X-ray (EDX) analysis and the values obtained were close to the nominal ones, i.e. 20 wt.% Pt₂CrCO/CMK-3. Electrochemical measurements were carried out using rotating disk electrode (RDE) technique in oxygen-saturated sulfuric acid solution in absence and presence of dissolved methanol. Besides other species and parameters, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis revealed the formation of an ordered Pt₃Cr alloy phase and the surface enrichment by Cr₂O₃ species with the rise of the annealing temperature. The last, in conjunction with the absence of Pt sites with (110) orientation, enhances the catalytic activity toward the ORR and the methanol tolerance. Kinetic parameters are reported and analyzed in terms of the physicochemical properties of the catalysts obtained by the X-ray techniques.