Thermochemical analysis of Mo-C-H system for synthesis of molybdenum carbides

Highlights: • Methane is the best hydrocarbon for molybdenum carbide synthesis. • Design of decarburization via hydrogen methanization using thermodynamic analysis. • Successful synthesis of single carbide-phase molybdenum carbide nanoparticles. • Surface area increased from 5 to 360 m²/g because of the decarburization treatment. -- Abstract: Earth abundant materials such as molybdenum carbide are gaining importance over expensive, precious metals such as ruthenium and platinum as catalysts for heterogeneous and electrochemical reaction systems. Despite its attributes, molybdenum carbide has not been developed as a commercial catalyst due to a lack of knowledge about the material, its structure and composition. As a result, most synthesis processes yield low surface area molybdenum carbide with contaminants such as excess carbon. In this study, we carried out DFT assisted thermodynamic modeling to better understand molybdenum carbon phase behavior. Our gas phase equilibrium studies led to better comprehension and refinement of synthesis parameters and conditions. With the help of these thermochemical models, we were able to design a decarburization via hydrogen methanization treatment that yielded 2 nm MoC particles free of contaminants with the highest surface areas reported so far i.e. up to 360 m²/g.