Platinum Ruthenium Catalysts Supported on Carbon Xerogel for Methanol Electro-Oxidation: Influence of the Catalyst Synthesis Method

A high surface area, highly mesoporous carbon xerogel was synthesised and used as a support in the preparation of platinum–ruthenium catalysts by different synthetic routes. The platinum–ruthenium carbon xerogel catalysts were physico‐chemically characterised and used for the chemical electro‐oxidation of methanol. The synthetic routes pursued included: 1) impregnation with metal chloride precursors and reduction with two different reducing agents: sodium borohydride and formic acid; 2) a microemulsion‐based method and 3) a sulfite complex method, which led to catalysts with different physico‐chemical features that strongly influence their catalytic behaviour towards methanol oxidation. The electro‐oxidation of methanol was found to depend on both the crystal size and the extent of active phase reduction as well as on the platinum concentration on the catalyst surface, which were maximised for the impregnation method and reduction with formic acid. From xero to hero: The effect of different synthesis methods on the characteristics of PtRu catalysts supported on carbon xerogels is studied and methanol oxidation activity (expressed in terms of mass activity) is analyzed. The impregnation method and reduction with HCOOH renders the highest catalytic activity, owing to larger crystal sizes and more surface Pt. Catalytic activity results from the appropriate combination of crystal size and Pt/Ru atomic ratio.