Ruthenium-loaded metal hydrides with hydrogen vacancies function as efficient catalysts for ammonia synthesis under low temperature and low pressure conditions.

The development of transition metal intermetallic compounds, in which active sites are incorporated in lattice frameworks, has great potential for modulating the local structure and the electronic properties of active sites, and enhancing the catalytic activity and stability. Here we report that a new copper-based intermetallic electride catalyst, LaCuSi, in which Cu sites activated by anionic electrons with low work function are atomically dispersed in the lattice framework and affords selective hydrogenation of nitroarenes with above 40-times higher turnover frequencies (TOFs up to 5084 h) than well-studied metal-loaded catalysts. Kinetic analysis utilizing isotope effect reveals that the cleavage of the H-H bond is the rate-determining step. Surprisingly, the high carrier density and low work function (LWF) properties of LaCuSi enable the activation of hydrogen molecules with extreme low activation energy (E = 14.8 kJ·mol). Furthermore, preferential adsorption of nitroarenes via a nitro group is achieved by high oxygen affinity of LaCuSi surface, resulting in high chemoselectivity. The present efficient catalyst can further trigger the hydrogenation of other oxygen-containing functional groups such as aldehydes and ketones with high activities. These findings demonstrate that the transition metals incorporated in the specific lattice site function as catalytically active centers and surpass the conventional metal-loaded catalysts in activity and stability.

The lack of efficient catalysts for ammonia synthesis from N 2 and H 2 gases at the lower temperature of ca. 50°C has been a problem not only for the Haber-Bosch process, but also for ammonia production toward zero CO 2 emissions. Here, we report a new approach for low temperature ammonia synthesis that uses a stable electron-donating heterogeneous catalyst, cubic CaFH, a solid solution of CaF 2 and CaH 2 formed at low temperatures. The catalyst produced ammonia from N 2 and H 2 gases at 50°C with an extremely small activation energy of 20 kJ mol −1 , which is less than half that for conventional catalysts reported. The catalytic performance can be attributed to the weak ionic bonds between Ca 2+ and H − ions in the solid solution and the facile release of hydrogen atoms from H − sites.

Suzuki cross-coupling reactions catalyzed by palladium are powerful tools for the synthesis of functional organic compounds. Excellent catalytic activity and stability require negatively charged Pd species and the avoidance of metal leaching or clustering in a heterogeneous system. Here we report a Pd-based electride material, Y3Pd2, in which active Pd atoms are incorporated in a lattice together with Y. As evidenced from detailed characterization and density functional theory (DFT) calculations, Y3Pd2 realizes negatively charged Pd species, a low work function and a high carrier density, which are expected to be beneficial for the efficient Suzuki coupling reaction of activated aryl halides with various coupling partners under mild conditions. The catalytic activity of Y3Pd2 is ten times higher than that of pure Pd and the activation energy is lower by nearly 35%. The Y3Pd2 intermetallic electride catalyst also exhibited extremely good catalytic stability during long-term coupling reactions.