Dissolution of Pt during Oxygen Reduction Reaction\nProduces Pt Nanoparticles

Abstract

The loss of Pt during\nthe oxygen reduction reaction (ORR) affects\nthe performance and economic viability of fuel cells and sensors.\nOur group previously observed the dissolution of Pt nanoelectrodes\nat moderately negative potentials during the ORR. Here we report a\nmore detailed study of this process and identify its product. The\nnanoporous Pt surface formed during the ORR was visualized by AFM\nand high-resolution SEM, which also showed ∼5 nm sized Pt particles\non the glass surface surrounding the electrode. The release of these\nnanoparticles into the solution was confirmed by monitoring their\ncatalytically amplified collisions with a Hg-coated microelectrode\nused as the tip in the scanning electrochemical microscope (SECM).