Boosting Electrocatalytic Nitrogen Reduction on Cobalt-Based Perovskite via Regulating Reaction Pathway Through Donation-Back-Donation Modulation

Abstract

The electrocatalytic approach of combining N₂ and H₂O to produce ammonia, known as the electrocatalytic N₂ reduction reaction (eNRR), has garnered significant attention due to its environmental benefits and potential for supporting a decentralized agricultural economy. However, the underlying chemistry governing the reaction pathways remains poorly understood, hindering the design of low-cost and efficient eNRR catalysts. Here we report the enhancement of the electrocatalytic eNRR activity of perovskite oxides by tuning the reaction pathway through a “donation-back-donation” mechanism. This is achieved by controlling the spin state via adjusting the distribution of d orbital electrons in low-cost transition metals, such as cobalt. Specifically, the cobalt in perovskite SrCoO₃ (SC) with a low-spin state demonstrates an 18 times higher ammonia yield rate compared to that in Co₃O₄ and 1.5 times higher than cobalt in perovskite LaCoO₃ (LC). The low spin states of cobalt in SC enable better control of the eNRR reaction pathway over the transformation of *N₂H to *NHNH or *NNH₂, resulting in alternating hydrogenation in SC rather than distal hydrogenation in LC with a high spin state. The unprecedented improvement in eNRR by regulating the spin state of Co demonstrates the bright of low-cost Co-based electrocatalysts for ammonia production.