| Abstract
| - The particle size effect on the formation of OH adlayer, the CO bulk oxidation, and the oxygen reductionreaction (ORR) have been studied on Pt nanoparticles in perchloric acid electrolyte. From measurements ofthe CO displacement charge at controlled potential, the corresponding surface charge density versus potentialcurves yielded the potentials of total zero charge (pztc), which shifts approximately 35 mV negative bydecreasing the particle size from 30 nm down to 1 nm. As a consequence, the energy of adsorption of OHis more enhanced, that is, at the same potential the surface coverage with OH increases by decreasing theparticle size, which in turn affects the catalytic reactions thereon. The impact of the electronically inducedpotential shift in the OH adsorption is demonstrated at the CO bulk oxidation, in which adsorbed OH is aneduct species and promotes the reaction, and the ORR, where it can act as a surface site blocking species andinhibits the reaction.
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