Work Function-Tailored Nitrogenase-like Fe Double-Atom Catalysts on Transition Metal Dichalcogenides for Nitrogen Fixation
Xue Yao, Zhiming Zhang, Lixin Chen, Zhiwen Chen, Yong Zhu, Chandra Veer Singh
Abstract
The work function–activity relationship provides a new strategy to design catalysts by tailoring the work function. A lower work function (φ) is widely believed to be in favor of better catalytic activity due to the easier electron transfer from the catalyst surface to reactants and/or intermediates. In this work, the φ values of nitrogenase-like Fe double-atom catalysts (Fe 2 /MX 2, MX 2: transition metal dichalcogenides) were tailored by altering the MX 2 supports for nitrogen (N 2 ) fixation. By density functional theory calculations, it is found that a lower φ caused by the increasing period number of the transition metal or chalcogen of MX 2 impairs the catalytic activity. This abnormal φ-activity relationship is mainly due to the overstrong N 2 adsorption on Fe 2 /MX 2 . Based on our strategy, Fe 2 /VS 2, Fe 2 /CrS 2, Fe 2 /MoS 2, and Fe 2 /WS 2 having relatively large φ values (4.44–5.81 eV) show excellent activity toward N 2 fixation with the overpotential values of 0.21–0.25 V.