关键词: PEMFC, 表面扩散, 成流机理, 氧还原反应, 阴极催化层

Abstract: A PEMFC electrode consisting of dual-layer catalyst layer(CL) was fabricated in this work.The outer CL was Nafion-free,while the inner CL was Nafion-bonded.The effects of Pt/C catalyst in the outer CL that did not contact with Nafion on the current generation in PEMFC electrodes were investigated.Cyclic voltammetric studies indicated that the Pt/C catalyst in the outer CL without direct contact with Nafion was still electrochemically active in taking part in the adsorption/desorption of hydrogen and the electrochemical oxidation/reduction of the oxygen-containing species occurring at the interface of "Pt/Nafion" in the inner CL.The polarization curves showed that the output voltage of the single cell was enhanced obviously by the outer CL when the current density was lower than 0.2A/cm2.The phenomena indicated that the Pt/C catalyst without direct contact with Nafion also participated in the electrochemical reduction of oxygen at the interface of "Pt/Nafion" via the surface diffusion of the adsorbed oxygen-containing species.

Key words: PEMFC, surface diffusion, current-generation mechanism, oxygen reduction reaction, cathode catalyst layer