Boosting oxygen transport through mitigating the interaction between Pt and ionomer in proton exchange membrane fuel cell

Abstract

The key to operating low-cost and high-power proton exchange membrane fuel cell (PEMFC) is reducing local oxygen transport resistance (Rionomer) from Pt/ionomer interface in cathode with low Pt loading. Herein, we design a high-oxygen mass-transfer Pt/ionomer interface via chemical modification of Pt/C catalyst with 1-Hexadecanethiol (C16SH) by self-assembled monolayers (SAMs) method. With a concentration of 0.3 mM, C16SH is selectively adsorbed on Pt nanoparticles and constructs a hydrophobic Pt/C surface, which can effectively reduce.-SO3H density around Pt active sites and the specific Pt/ionomer interface is obtained after C16SH is removed by in situ electrochemical oxidation. Consequently, compared with the performance of membrane electrode assembly (MEA) from unmodified catalyst, the voltage of C16SH-modified MEA increases by 45 and 82 mV, respectively, at 1500 and 2000 mA cm−2 at RH 100%. The decrease in oxygen transport resistance plays a key role in improving polarization performance, relative to the increase in H+ transport resistance. Moreover, according to limiting current density method, the reduced Rionomer from Pt/ionomer interface is the essential reason for the improved oxygen transport. In general, this work highlights a promising method to boost oxygen transport and enhance performance of PEMFC through mitigating the interaction between Pt and ionomer.