UC Berkeley

Ternary metal nitrides are a promising class of functional materials, but their variety has been limited by the challenging nature of nitride synthesis. Here, we demonstrate a facile self-combustion synthesis route to novel ternary molybdenum nitrides. The room temperature mixing of NaNH2, MoCl4, and 3d transition metal chlorides, such as MnCl2, FeCl2, and CoCl2, initiates a highly exothermic metathesis reaction, which is thermodynamically driven by the formation of stable NaCl, N2, and NH3 byproducts. The rapid combustion reaction yields ternary rocksalt γ-TMxMo1-xN0.5 nanoparticles (TM = Mn, Fe, Co) in just a few seconds. We calculate from DFT that these disordered ternary molybdenum nitrides are thermodynamically stable under the high-temperatures at which they form but are remnantly metastable when quenched to ambient conditions. Introduction of Mn, Fe, and Co into γ-Mo2N is found to change its magnetic properties and to enhance its oxygen reduction catalytic activities. Our work demonstrates self-combustion synthesis as a simple but powerful route for the realization of novel ternary intermetallic nitrides with emergent functionality.