How To Make Electrocatalysts More Active for Direct Methanol OxidationAvoid PtRu Bimetallic Alloys

Contrary to the current understanding of Pt−Ru electrocatalyzed oxidation of methanol, the bimetallic alloy is not the most desired form of the catalyst. In the nanoscale Pt−Ru blacks used to electrooxidize methanol in direct methanol fuel cells, Pt0Ru0 has orders of magnitude less activity for methanol oxidation than does a mixed-phase electrocatalyst containing Pt metal and hydrous ruthenium oxides (RuO x H y ). Bulk, rather than near-surface, quantities of electron−proton conducting RuO x H y are required to achieve high activity for methanol oxidation. The active catalyst forms a nanoscopic, phase-separated hydrons oxide-on-metal structure that retains the Pt metal−RuO x H y boundaries required to oxidize methanol fully to carbon dioxide and water.