Electrocatalytic nitrate reduction reaction (NO3RR) presents a sustainable strategy for concurrently remediating nitrate (NO3–) pollution and producing valuable ammonia (NH3). However, its practical application is hindered by sluggish kinetics, particularly on copper (Cu)-based catalysts, which often suffer from inefficient water dissociation, leading to low NH3 selectivity and accumulation of toxic nitrite byproducts. Here, we report the design of copper nanodendrites (Cu NDs) as highly effective NO3RR electrocatalysts. We demonstrate that the sharp tips of the Cu NDs generate localized and intense electric fields. These tip-enhanced fields drive the enrichment of hydrated potassium ions, which in turn significantly accelerates the water dissociation step, ensuring a sufficient supply of active hydrogen (H*) for deep hydrogenation. As a result, the Cu ND catalyst achieves an exceptional NH3 yield rate of 2.58 mmol h–1 cm–2 and a Faradaic efficiency (FE) of 96.91% at −0.6 V versus reversible hydrogen electrode. Remarkably, the catalyst exhibits outstanding durability, maintaining over 96% NH3 FE during a 300 h continuous test. In a membrane electrode assembly designed for practical application, the FE of NH3 surpasses 90% for over 100 h. Furthermore, we demonstrate a scalable product separation process using air stripping, recovering nearly 98% of the produced NH3 and converting over 80% into high-purity NH4Cl and NH3·H2O. This work presents a catalyst design strategy that overcomes a key kinetic bottleneck in the NO3RR and bridges the gap between fundamental catalysis and practical application.
Zhang et al. (Mon,) studied this question.