The catalytic activity and methanol tolerance of transition metal modified-ruthenium–selenium catalysts

The activity of ruthenium-based catalysts towards oxygen reduction was enhanced by addition of tungsten, molybdenum and rhodium. The catalysts were produced by decarbonylation of the ruthenium and transition metal carbonyls in the presence of selenium (sulphur) and carbon powders. The produced materials were characterised by scanning electron microscopy and energy dispersive spectroscopy as well as by electrochemical evaluations in both half cells and direct methanol fuel cells. All transition metal-modified catalysts exhibited better performance than those of ruthenium–selenium (sulphur) alone, but the tungsten modification seemed the best approach. The RuSe0.20W0.29 catalyst delivered the maximum power density of up to 40 mW cm−2. The improvement is a consequence of the enhanced activity towards oxygen reduction with a minor loss in methanol tolerance as well as a stabilising effect of tungsten on catalysts. The new catalysts were compared to Pt and to sulphur-containing catalysts.