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

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 (CoO_x@Pt). This design exploits the strong Pt/oxide interaction, which grants the catalyst its high structural and chemical durability without sacrificing activity. The CoO_x@Pt nanocatalyst delivers a high initial mass activity of 1.10 A mg_Pt⁻¹, a rated power density of 1.04 W cm⁻² and a Pt utilization of 10.4 W mg_Pt⁻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. (Figure presented.)