In Situ Nitrogen Infiltration into an Ordered Pt3Co Alloy with sp–d Hybridization to Boost Fuel Cell Performance

Reducing the dosage of Pt while achieving high activity and stability remains a significant challenge in developing a cathode catalyst for the H2/air-fed fuel cell. Here, we employed N-doped carbon derived from small organic molecules as N sources to prepare a fully N-doped ordered Pt3Co catalyst (IM-Pt3CoN) for the oxygen reduction reaction (ORR). This unique approach precisely controls the in situ capture of N atoms during the high-temperature alloying process of ordered Pt3Co nanoparticles (NPs), allowing full interstitial doping of N atoms within the gaps of Pt3Co intermetallic nanocrystals. The nitrogen-implanted IM-Pt3Co with increased vacancy formation energy of Pt/Co and optimized d band can restrain the tendency of Pt/Co dissolution and weaken the binding of oxygenated species, leading to improved ORR activity and durability. Remarkably, the IM-Pt3CoN catalyst demonstrated high performance in the H2–O2 fuel cell (a high power density of 2.4 W cm–2, 1.21 A/mgPt for mass activity (MA)) and enhanced stability (78.7% MA retained after 30k voltage cycles). Furthermore, in practical H2–air fuel cell tests, a peak power density of 1.01 W cm–2 and a voltage loss of only 28 mV at 0.8 A cm–2 after an accelerated durability test (ADT) can be achieved. These performance indicators exceed the Department of Energy (DOE) 2025 fuel cell technical targets.