Zirconium nitride catalysts surpass platinum for oxygen reduction

Platinum catalysts are widely used for oxygen reduction reactions in electrochemical devices but scalability is restricted by scarcity, cost and vulnerability to poisoning. Zirconium nitride nanoparticles now exhibit an oxygen reduction performance with similar activity to that of Pt on carbon. Platinum (Pt)-based materials are important components of microelectronic sensors, anticancer drugs, automotive catalytic converters and electrochemical energy conversion devices(1). Pt is currently the most common catalyst used for the oxygen reduction reaction (ORR) in devices such as fuel cells and metal-air batteries(2,3), although a scalable use is restricted by the scarcity, cost and vulnerability to poisoning of Pt (refs (4-6)). Here we show that nanoparticulate zirconium nitride (ZrN) can replace and even surpass Pt as a catalyst for ORR in alkaline environments. As-synthesized ZrN nanoparticles (NPs) exhibit a high oxygen reduction performance with the same activity as that of a widely used Pt-on-carbon (Pt/C) commercial catalyst. Both materials show the same half-wave potential (E-1/2 = 0.80 V) and ZrN has a higher stability (Delta E-1/2 = -3 mV) than the Pt/C catalyst (Delta E-1/2 = -39 mV) after 1,000 ORR cycles in 0.1 M KOH. ZrN is also shown to deliver a greater power density and cyclability than Pt/C in a zinc-air battery. Replacement of Pt by ZrN is likely to reduce costs and promote the usage of electrochemical energy devices, and ZrN may also be useful in other catalytic systems.