D-band center modulation of B-mediated FeS₂ to activate molecular nitrogen for electrocatalytic ammonia synthesis

Electrocatalytic nitrogen fixation is a promising approach for ambient ammonia synthesis. The key that limits the improvement of ammonia evolution performance is the N[tbnd]N bond cleavage of molecular nitrogen. One effective route to break this bottleneck is the d-band center modulation of catalysts. Herein, a nonmetal boron mediated FeS₂ (B-FeS₂) is developed for electrocatalytic nitrogen fixation. The B-mediation alters the spin-orbits of Fe site and upshifts the d-band center of FeS₂, thus inducing a strong d-π* interaction between the Fe site and nitrogen to activate N[tbnd]N bond. Besides, the experimental and theoretical calculations indicate the B-mediation reduces the energy barrier for *NNH intermediate, thus significantly accelerating ammonia production. As a result, B-FeS₂ displays high ammonia yield (1.56 mmol·g⁻¹·h⁻¹) with 12.6 % Faradaic efficiency. This strategy of d-band center tuning induced by the B-mediation provides a distinctive insight for the design of high-efficiency electrocatalysts.