Tungsten oxide as active matrix for dispersed carbon-supported RuSex nanoparticles:: Enhancement of the electrocatalytic oxygen reduction

Modification of carbon-supported RuSex nanoparticles with ultra-thin WO3 films results in the enhancement of their electrocatalytic properties towards electroreduction of dioxygen in acid medium (0.5 mol d m(-3) H2SO4) as evidenced from the positive shift of the O-2 reduction potential (ca. 150 mV) and the higher heterogeneous rate constant (ca. 3 times). An important issue is that the mixed-valent tungsten(VI,V) oxide support is characterized by good electronic and protonic conductivities. Further, not only Ruse, is catalytic but tungsten oxide itself is also capable of promoting the reduction of hydrogen peroxide. This bifunctional activity of the WO3-modified system has been the most pronounced at rather low loadings (e.g. 80 mu g cm(-2)) of Ruse(x) nanoparticles. To facilitate attachment of catalytic particles to glassy carbon substrate, they have been over-coated with Nafion. (c) 2006 Elsevier B.V. All rights reserved.