Iron-based cathode catalyst with enhanced power density in polymer electrolyte membrane fuel cells

Abstract

H(2)-air polymer-electrolyte-membrane fuel cells are electrochemical power generators with potential vehicle propulsion applications. To help reduce their cost and encourage widespread use, research has focused on replacing the expensive Pt-based electrocatalysts in polymer-electrolyte-membrane fuel cells with a lower-cost alternative. Fe-based cathode catalysts are promising contenders, but their power density has been low compared with Pt-based cathodes, largely due to poor mass-transport properties. Here we report an iron-acetate/phenanthroline/zeolitic-imidazolate-framework-derived electrocatalyst with increased volumetric activity and enhanced mass-transport properties. The zeolitic-imidazolate-framework serves as a microporous host for phenanthroline and ferrous acetate to form a catalyst precursor that is subsequently heat treated. A cathode made with the best electrocatalyst from this work, tested in H(2)-O(2,) has a power density of 0.75 W cm(-2) at 0.6 V, a meaningful voltage for polymer-electrolyte-membrane fuel cells operation, comparable with that of a commercial Pt-based cathode tested under identical conditions.

High‐Performance Direct Methanol Fuel Cells with Precious‐Metal‐Free Cathode

“…In a search for high‐performance alternative NPMCs to Pt cathode over the last decade, significant progress has been made from new catalyst synthesis 6, 7, 8, 9, 10. Among the studied formulations, iron‐nitrogen‐carbon (Fe‐N‐C) catalysts are the most promising in terms of their activity and stability in more challenging acidic electrolytes 11, 12, 13, 14, 15.…”

Unraveling the Nature of Sites Active toward Hydrogen Peroxide Reduction in Fe‐N‐C Catalysts

“…We also demonstrated that FeN x C y moieties and Fe@N‐C species are moderately active toward PRR, proving their possible roles in both direct (major path) and indirect 4 e − ORR pathways. Since the synthesis of Fe‐N‐C catalysts with only FeN x C y moieties,10b, 15 only Fe@N‐C particles,10a or their combination3b,3d, 17 is now controllable, the understanding of the nature of active sites for PRR provided herein offers new insights for the rational design of advanced Fe‐N‐C catalysts with high selectivity and expectedly improved durability in polymer electrolyte fuel cells. …”

Cobalt Oxide and Cobalt‐Graphitic Carbon Core–Shell Based Catalysts with Remarkably High Oxygen Reduction Reaction Activity

“…Polymer electrolyte membrane fuel cell (PEMFC) offers much higher fuel efficiency and lower point‐of‐use emission over the combustion engine 1. These advantages, in addition to longer operating time and fast refueling, render it more competitive than the conventional battery devices.…”

“…These advantages, in addition to longer operating time and fast refueling, render it more competitive than the conventional battery devices. PEMFC has indeed drawn a growing market share in light duty vehicle, bus and material handling vehicle propulsion as well as in back‐up and remote power systems 1. The efficiency and performance of the widely used low temperature version of this device, however, is limited by the oxygen (O 2 ) reduction reaction (ORR) at or near ambient temperature on its cathode side 2.…”