Improving Pt Utilization and Electrochemical Activity of Proton Exchange Membrane Fuel Cells Through Surface Modification of Carbon Nanotube Catalyst Support

The main hindrances in commercializing hydrogen fuel cells are the high catalyst cost, sluggish oxygen reduction reaction (ORR) kinetics, and low durability over long cycling. Herein, a low-Pt-based efficient cathode catalyst decorated on nitrogen-doped carbon nanotube (CNT) support is developed. The effect of N doping and chemical etching of CNTs on the performance of proton exchange membrane fuel cells (PEMFC) are demonstrated in this work. Half-cell studies showed that Pt decorated N-doped etched carbon nanotubes (Pt/NECNT) exhibit higher electrochemical surface area, onset potential, specific activity, and mass activity than Pt/CNT, Pt/ECNT, Pt/NCNT, and commercial Pt/C samples. In contrast to the commercial Pt/C catalyst, minimal loss in limiting current density and half-wave potential is observed for Pt/NECNT catalyst even after the 10000th ADT cycle. From single-cell study, the peak power density of 950 mW cm-2 and operational power density of 840 mW cm-2 (at 0.6 V) are obtained using Pt/NECNT cathode catalyst at 80 degrees C with low Pt loading. The remarkable enhancement in the electrocatalytic activity, kinetic property, and high durability of Pt/NECNT are ascribed to the N doping and surface modification of CNT support. N-doping and etching of carbon nanotubes (CNT) synergistically help in better dispersion of platinum (Pt) nanoparticles, which eventually help to achieve high power density (Pmax=950 mW cm-2) with low Pt loading. The faster kinetics and lower activation loss corroborate Pt decorated N-doped etched CNT as an efficient catalyst for proton exchange membrane fuel cells.image (c) 2024 WILEY-VCH GmbH