A bioinspired sulfur-surrounded iron catalyst for ammonia synthesis

Abstract

A nitrogenase-inspired inorganic compound consisting of iron (Fe) and molybdenum disulfide (MoS₂) is designed with a promising capability of N₂ fixation using first principles. Three Fe atoms are anchored on MoS₂ to construct an Fe₃S₃ cluster, which resembles the active component of the FeMo-cofactor in nitrogenase. This similarity is evidenced not only in the geometric configuration of the two structures but also in their electronic properties. In the process of N₂ fixation, the Fe and S moieties function as electron reservoir and buffer, respectively. The N₂ activation mechanism and a reaction network for NH₃ synthesis are elaborately investigated. The reaction pathway of N₂ alternative hydrogenation involving *NHNH₂ to *NH/*NH₃ is more favorable than N₂ distal hydrogenation. Further microkinetic modeling simulations show that the optimal reaction route has a high turnover frequency of 4.4 × 10⁻⁴ site⁻¹ s⁻¹ under the typical Haber–Bosch process reaction conditions. The development of this novel biomimetic catalyst presents a promising avenue for environmentally sustainable and high-performance catalyst design for ammonia synthesis.