Visible-Light-Driven Ruthenium-Catalyzed Hydrogenation of Manganese Nitride Complexes to Ammonia under Ambient Conditions

Abstract

In recent years, photocatalytic hydrogenation of metal nitrides to ammonia using solar energy as a renewable energy source and green hydrogen as both an electron and a proton source under ambient reaction conditions has been intensively investigated to achieve one of the most desirable next-generation scientific techniques, i.e., atom-economical ammonia production from dinitrogen and dihydrogen, thereby contributing to a carbon-neutral society. In this study, we have successfully developed visible-light-driven photocatalytic hydrogenation of manganese nitride complexes to ammonia at room temperature under an ambient pressure of dihydrogen in the presence of diruthenium complexes as dihydrogen oxidation catalysts and iridium complexes as photosensitizers. The turnover numbers based on the diruthenium complex and the yield of ammonia based on the manganese nitride complex reached up to 150 equiv. and 91%, respectively, indicating the high durability and efficiency of this photocatalytic system. Moreover, this hydrogenation proceeded photocatalytically even at a significantly low partial pressure of dihydrogen (down to 0.05 atm), which was much lower than in previous systems reported by other research groups, and would be a key process for paving the way for achieving the photocatalytic ammonia formation under an ambient pressure of a mixture of dinitrogen and dihydrogen.