Solution synthesis of Cu₃PdN nanocrystals as ternary metal nitride electrocatalysts for the oxygen reduction reaction

The synthesis of transition metal nitride nanoparticles is challenging, in part because the unreactive nature of the most common nitrogen reagents necessitates high-temperature and/or high-pressure reaction conditions. Here we report the solution-phase synthesis and characterization of antiperovskite-type Cu₃PdN nanocrystals that are multifaceted, uniform, and highly dispersible as colloidal solutions. Colloidal Cu₃PdN nanocrystals were synthesized by reacting copper(II) nitrate and palladium(II) acetylacetonate in 1-octadecene with oleylamine at 240 °C. The Cu₃PdN nanocrystals were evaluated as electrocatalysts for the oxygen reduction reaction (ORR) under alkaline conditions, where both Cu₃N and Pd nanocrystals are known to be active. The ORR activity of the Cu₃PdN nanocrystals appears to be superior to that of Cu₃N and comparable to that of Pd synthesized using similar methods, but with significantly improved mass activity than Pd control samples. The Cu₃PdN nanocrystals also show greater stability than comparably synthesized Pd nanocrystals during repeated cycling under alkaline conditions.