Low Pt Loaded Nitrogen Doped Carbon As Efficient Catalyst Support for Proton Exchange Membrane Fuel Cells

Abstract

Proton exchange membrane fuel cells are one of the promising renewable energy technologies, which generate electricity by utilizing hydrogen and oxygen as fuel and oxidant respectively. Platinum is so far the best catalyst for fuel cells. But for cost effective as well as efficient fuel cells, synthesizing low loading of platinum without hampering the performance has become the necessity of research. Roadmap for the development of PEMFC electrocatalyst by achieving DOE’s 2020 target of low Pt-loading 0.125 mgPt cm-2 with a deliverable power density of 0.9-1 Wcm-2. In order to achieve that target, catalytically active, highly conducting stable support materials are needed to decorate Platinum. In this work, nitrogen doped high surface area conducting carbon has been used as the support for the ultra small platinum nanoparticles. Nitrogen doping has been done using a bio-waste precursor whereas ultra small platinum nanoparticles (2-3 nm) has been decorated using polyol reduction method. ORR performance and stability of the catalysts were investigated using half-cell study (RDE, RRDE, and cyclic voltammetry) to fully understand the catalytic activity, which also shows the 4-electron transfer for the catalyst in 0.5 M H2SO4 solution. Full cell studies has been carried out using Pt/NC catalyst at the cathode and Pt/C at anode maintaining Pt-loading of 0.1 mgPt cm-2 on both the sides which resulted in a maximum power density of ~710 mW/ cm2 and 904 mW cm-2 at 60 C without and with iR correction which is comparatively higher than conventional catalysts. Mass activity of the catalyst has been found to be 686 A/g for 0.84 V, where as the maximum current density obtained was 2.3 A/ cm2 at 0.25 V. Power density of ~500 mW cm-2 was obtained at 0.6 V (without any iR correction) which complies to the DOE standards. Further modifications were done in order to reduce the iR losses at high current density and are discussed.