Size effects of ultrafine palladium particles on the electrocatalytic oxidation of CO

Effects of palladium particle size on the electrocatalytic oxidation of carbon monoxide in an acidic solution have been examined by the use of modeled catalyst electrodes (View the MathML source) with a flat and dense glassy carbon substrate. The cyclic voltammetry showed that higher overpotential is needed to oxidize carbon monoxide on palladium with a decrease in the palladium particle size. With decreasing size of palladium particles the oxidation of carbon monoxide seems to shift from a one-electron-transfer controlled mechanism to a two-electron-transfer controlled one.