This material is based on work supported by the U.S.Department of Energy under award no. DE-EE0034250. Theauthors wish to acknowledge the team and institutionsinvolved in this work: Arizona State University, Sandia National Laboratories, and Georgia Institute of Technology.The assistance in nitride synthesis by Nathaniel Anbar, SyedShakeel, and Jarett Prince is also greatly acknowledged. Wegratefully acknowledge the use of facilities within the EyringMaterials Center at Arizona State University supported in partby NNCI-ECCS-1542160, and in particular David Wright forhis above-and-beyond help and support with our firstsuccessful nitride synthesis. This article has been authored byan employee of National Technology & Engineering Solutions of Sandia, LLC under Contract No. DE-NA0003525 with the U.S. Department of Energy (DOE). The employee owns allright, title and interest in and to the article and is solelyresponsible for its contents. The United States Governmentretains and the publisher, by accepting the article forpublication, acknowledges that the United States Governmentretains a non-exclusive, paid-up, irrevocable, world-wide licenseto publish or reproduce the published form of this article orallow others to do so, for United States Government purposes.The DOE will provide public access to these results of federallysponsored research in accordance with the DOE Public AccessPlan https://www.energy.gov/downloads/doe-public-access-plan. This paper describes objective technical results andanalysis. Any subjective views or opinions that might beexpressed in the paper do not necessarily represent the views ofthe U.S. Department of Energy or the United States Government.

Over the past few decades, inorganic nitride materials have grown in importance in part due to their potential as catalysts for the synthesis of NH3, a key ingredient in fertilizer and precursor to industrial chemicals. Of particular interest are the ternary (ABN) or higher-order nitrides with high metal-to-nitrogen ratios that show promise in enhancing NH3 synthesis reaction rates and yields via heterogeneous catalysis or chemical looping. Although metal nitrides are predicted to be numerous, the stability of nitrogen triple bonds found in N2, especially in comparison to the metal-nitrogen bonds, has considerably hindered synthetic efforts to produce complex nitride compounds. In this study, we present an exhaustive down-selection process to identify ternary nitrides for a promising chemical looping NH3 production mechanism. We also report on a facile and efficient two-step synthesis method that can produce well-characterized η-carbide Co3Mo3N/Fe3Mo3N or filled β-manganese Ni2Mo3N ternaries, as well as their associated quaternary, (Co,Fe)3Mo3N, (Fe,Ni)2Mo3N, and (Co,Ni)2Mo3N, solid solutions. To further explore the quaternary space, syntheses of (Co,Ni)3Mo3N (Ni ≤ 10 mol %) and Co3(Mo,W)3N (W ≤ 10 mol %) were also investigated. The structures of the nitrides were characterized via X-ray powder diffraction. The morphology and compositions were characterized with scanning electron microscopy. The multitude of chemically unique, but structurally related, nitrides suggests that properties such as nitrogen activity may be tunable, making the materials of great interest for NH3 synthesis schemes. © 2023 American Chemical Society.

Ternary nitride down-selection with non-metals andCo3Mo3N sample screening (Supporting Information)

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