Embedded oxide clusters stabilize sub-2 nm Pt nanoparticles for highly durable fuel cells

Abstract

Platinum (Pt) nanocatalysts are essential for facilitating the cathodic oxygen reduction reaction in proton exchange membrane fuel cells but suffer from a trade-off between activity and durability. Here we present the design of a fine nanocatalyst comprising Pt nanoparticles with sparsely embedded cobalt oxide clusters (CoOx@Pt). This design exploits the strong Pt/oxide interaction, which grants the catalyst its high structural and chemical durability without sacrificing activity. The CoOx@Pt nanocatalyst delivers a high initial mass activity of 1.10 A mgPt−1, a rated power density of 1.04 W cm−2 and a Pt utilization of 10.4 W mgPt−1 in a membrane electrode assembly. It exhibits a notably high durability that features a mass activity retention of 88.2%, a voltage loss of 13.3 mV at 0.8 A cm−2 and a small rated power loss of 7.5% after accelerated stress testing. This durability could offer a long projected lifetime of 15,000 hours and may greatly reduce the lifetime-adjusted cost. Pt-based catalysts are state-of-the-art cathodes in fuel cells, but they experience a trade-off between activity and durability. Now a Pt nanocatalyst with embedded cobalt oxide clusters is shown to promote stability during proton exchange membrane fuel cell operation without sacrificing activity, achieving 88.2% mass activity retention after 30,000 accelerated stress test cycles.