Weakened d-p orbital hybridization in in situ reconstructed Ru/β-Co(OH)2 heterointerfaces for accelerated ammonia electrosynthesis from nitrates

The electrocatalytic nitrate reduction reaction (NtrRR) has recently become an emerging technology that can convert nitrate pollutants into high-value added ammonia products in a mild manner. However, it is highly challenging to develop NtrRR electrocatalysts with high activity, selectivity, and stability given the sluggish kinetics and diverse pathways of the NtrRR. Herein, we develop a Ru/beta-Co(OH)(2) heterostructure catalyst derived from in situ reconstruction of Ru-doped Co metal nanosheets with an ultralow Ru/Co ratio of 3.08 at%. The synergy and strong interactions between interfacial Ru and Co sites weaken the d-p orbital hybridization ability with *NH3 intermediates, which thus lowers the barrier of the potential determining step. As a result, the catalyst delivers an industrial-level current density of -500 mA cm(-2) at a positive potential of only 0.01 V vs. the reversible hydrogen electrode, along with a high ammonia Faradaic efficiency of 98.78%. Meanwhile, it can purify the nitrate sewage and reduce the nitrate concentration to 13-31 ppm. Furthermore, the assembled Zn-nitrate flow battery also delivers a decent power density of 29.87 mW cm(-2) and a high ammonia yield of up to 0.38 mmol h(-1) cm(-2) with excellent stability. This work suggests an effective strategy for designing high-performance electrocatalysts through interface engineering by rational reconstruction.

Automated summary

Researchers have developed a Ru/beta-Co(OH)(2) heterostructure catalyst that shows high activity, selectivity, and stability in electrocatalytic nitrate reduction reaction. The catalyst efficiently converts nitrate pollutants into valuable ammonia products.