O-2 REDUCTION ON AN INK-TYPE ROTATING-DISK ELECTRODE USING PT SUPPORTED ON HIGH-AREA CARBONS

The kinetics of O-2 reduction has been examined on an ink-type electro de made with Pt supported on high-area carbon. Electrocatalysts with 5 -40 mass % of Pt on Black Pearls, Vulcan XC-72, and Shawinigan acetyle ne black carbons were used. Experiments were performed in 0.1 M soluti ons of H2SO4, H3PO4, HClO4, and NaOH. Kinetic parameters of O-2 reduct ion were found to be similar as on a smooth Pt surface. No influence o f the type of carbon was observed. The mass activity of O-2 reduction was independent of Pt loading at low currents, but at high currents th e mass activity decreased with an increase in Pt loading. It is sugges ted that mass-transfer limitations are responsible for the different i nfluence of Pt loading on mass activity at low and high currents. Repr oducibility of the measurements on the ink electrode was satisfactory, and it is recommended for investigations df dispersed electrocatalyst s.