Molecular-level insight into photocatalytic reduction of N2 over Ruthenium single atom modified TiO2 by electronic Metal-support interaction

The sustainable production of NH3 by fixing N2 under mild conditions via photocatalysis is fascinating compared to current industrial processes operated at critical conditions. However, the inert N2 is extremely difficult to adsorb and activate. And the transfer of photogenerated electrons to the NN bond is energetically challengeable. Herein, we presented a photocatalyst designed based on electronic metal-support interactions (EMSI), which proved to be a reliable strategy for improving the photocatalytic N2 fixation performance. The introduction of Ru single atoms into TiO2 by a molten salt method can stabilize the oxygen vacancies, thus achieving an ammonia yield rate of 18.9 μmol·g−1·h−1 under mild conditions without any sacrificial agent due to the significant enhancement of EMSI. The combination of experimental results with first-principles simulations confirmed that the EMSI can tune the local atomic structure and accelerate the transfer of photogenerated carriers between Ru single atoms and TiO2 carriers, thus effectively enhancing photocatalytic N2 reduction activity. Additionally, the alternating pathway is more favored route for NH3 formation on the optimized single atom Ru/TiO2. Our atomic-level design and mechanistic studies provided a new reference for efficiently photocatalytic nitrogen fixation.