Ammonia is crucial for the manufacture of nitrogen fertilizers and is also widely regarded as a promising energy or hydrogen carrier. Due to the high energy consumption of the industrial ammonia production, the development of alternative materials and approaches for efficient N2 reduction to ammonia under mild conditions is a long-sought goal. The employment of main group elements for this vital reaction has recently sparked interest because of new dinitrogen reaction chemistry.
Recently, a joint research group led by Prof. Ping Chen from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences and Prof. Tejs Vegge from Technical University of Denmark (DTU) published a research article on Angew. Chem. Int. Ed., titled “Transition-Metal-Free Barium Hydride Mediates Dinitrogen Fixation and Ammonia Synthesis”.
By experimental and computational studies, they revealed the reaction mechanism of nitrogen fixation and hydrogenation process on transition-metal-free barium hydride (BaH2). The creation of hydrogen vacancies leads to the formation of multiple coordinatively unsaturated Ba sites, which are responsible for the adsorption and activation of N2. The hydridic hydrogen acts as an electron donor and facilitates the activation of N2 with concurrent H2 release, which functionally resembles the molecular hydrido complexes and FeMo cofactor in nitrogenase. This is a helpful model for understanding the activation and hydrogenation of N2 to NH3 mediated by alkali and alkaline earth metal hydrides which has prospects in future technologies for ammonia synthesis using transition-metal-free materials.
This work was supported by National Natural Science Foundation of China and the Youth Innovation Promotion Association of Chinese Academy of Sciences. (Text Yeqin Guan)
Article links: https://doi.org/10.1002/anie.202205805
