Lattice-Confined Single-Atom Fe 1 S x on Mesoporous TiO 2 for Boosting Ambient Electrocatalytic N 2 Reduction Reaction.

Mimicking natural nitrogenase to create highly efficient single-atom catalysts (SACs) for ambient N 2 fixation is highly desired, but still challenging. Herein, S-coordinated Fe SACs on mesoporous TiO 2 have been constructed by a lattice-confined strategy. The extended X-ray absorption fine structure and X-ray photoelectron spectroscopy spectra demonstrate that Fe atoms are anchored in TiO 2 lattice via the FeS 2 O 2 coordination configuration. Theoretical calculations reveal that FeS 2 O 2 sites are the active centers for electrocatalytic nitrogen reduction reaction (NRR). Moreover, the finite element analysis shows that confinement of opened and ordered mesopores can facilitate the mass transport and offer an enlarged active surface area for NRR. As a result, this catalyst delivers a favorable NH 3 yield rate of 18.3 μg h -1  mg cat. -1 with a high Faradaic efficiency of 17.3 % at -0.20 V versus a reversible hydrogen electrode. Most importantly, this lattice-confined strategy is universal and can also be applied to Ni 1 S x @TiO 2 , Co 1 S x @TiO 2 , Mo 1 S x @TiO 2 , and Cu 1 S x @TiO 2 SACs. Our study provides new hints for the design and biomimetic synthesis of highly efficient NRR electrocatalysts.