Identification of M‐NH(2)‐NH(2) Intermediate and Rate Determining Step for Nitrogen Reduction with Bioinspired Sulfur‐Bonded FeW Catalyst

The multimetallic sulfur‐framework catalytic site of biological nitrogenases allows the efficient conversion of dinitrogen (N(2)) to ammonia (NH(3)) under ambient conditions. Inspired by biological nitrogenases, a bimetallic sulfide material (FeWS(x)@FeWO(4)) was synthesized as a highly efficient N(2) reduction (NRR) catalyst by sulfur substitution of the surface of FeWO(4) nanoparticles. Thus prepared FeWS(x)@FeWO(4) catalysts exhibit a relatively high NH(3) production rate of 30.2 ug h(−1) mg(−1) (cat) and a Faraday efficiency of 16.4 % at −0.45 V versus a reversible hydrogen electrode in a flow cell; these results have been confirmed via purified (15)N(2)‐isotopic labeling experiments. In situ Raman spectra and hydrazine reduction kinetics analysis revealed that the reduction of undissociated hydrazine intermediates (M‐NH(2)‐NH(2)) on the surface of the bimetallic sulfide catalyst is the rate‐determing step for the NRR process. Therefore, this work can provide guidance for elucidating the structure–activity relationship of NRR catalysts.