Jahn-Teller Distortions Induced by in situ Li Migration in λ-MnO 2 for Boosting Electrocatalytic Nitrogen Fixation.

Lithium-mediated electrochemical nitrogen reduction reaction (Li-NRR) completely eschews the competitive hydrogen evolution reaction (HER) occurred in aqueous system, whereas the continuous deposition of lithium readily blocks the active sites and further reduces the reaction kinetics. Herein, we propose an innovative in situ Li migration strategy to realize that Li substitutes Mn sites in λ-MnO 2 instead of evolving into the dead Li. Comprehensive characterizations corroborate that the intercalation of Li + at high voltage breaks the structural integrity of MnO 6 octahedron and further triggers unique Jahn-Teller distortions, which promotes the spin state regulation of Mn sites to generate the ameliorative e g orbital configuration and accelerates N≡N bond cleavage via e g -σ and e g -π* interaction. To this end, the resulted cationic disordered LiMnO 4 delivers the recorded highest NH 3 yield rate of 220 μg h -1  cm -2 and a Faradaic efficiency (FE) 83.80 % in organic electrolyte.