Electrocatalytic nitrate reduction (NO3 -RR) provides a sustainable pathway for NH3 production under ambient conditions. Although operation in neutral media is more practically relevant, the reaction generally suffers from sluggish kinetics and unfavorable hydrogenation steps, which collectively limit NH3 selectivity. Here, we develop a graphene-encapsulated CuFe alloy catalyst (CuFe-G) that enables highly efficient NO3 -RR via a dynamically generated CuFeδ+ surface active layer. The synergistic alloy interface drives the spontaneous conversion of NO3 - to NO2 -, while in Situ surface redox dynamics create an active CuFeδ+ layer that optimizes *NO adsorption and accelerates hydrogenation kinetics. In parallel, encapsulation of the dynamic CuFeδ+ species within multilayer graphene constructs a mechanically robust and highly conductive interface that stabilizes the active sites and facilitates rapid charge transport. As a result, CuFe-G delivers a peak NH3 Faradaic efficiency of 99.63% at -1.0 V vs. RHE, together with an NH3 yield rate of 8.03 mg h-1 mgcat -1. When integrated into a CuFe-G‖RuO2 electrolyzer, the system further achieves a current density of 400 mA cm-2 at 2.6 V and maintains a solar-to-ammonia efficiency of 4.1% under fluctuating illumination. This work therefore establishes a dynamically redox-regulated catalytic platform for sustainable, solar-driven nitrate-to-ammonia conversion.
Chen et al. (2026) studied this question.