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 NN 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 NN 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.