Despite the short-term industrial landscape remaining unchanged, green synthesis technologies for ammonia (NH3) and hydroxylamine (NH2OH) are critical for carbon neutrality. Alternatively, electrocatalytic nitrate reduction (NIRR) can be integrated with membrane separation technology via a modular design, simultaneously achieving pollution control and resource recovery. However, the microscopic mechanism of NIRR remains ambiguous given the complex dynamic catalytic interface, hindering advanced catalyst development. Here, we propose a three-step synergistic mechanism at dynamic catalytic interface, which integrates interfacial microenvironment regulation, OH species cycle, and reverse hydrogen spillover for efficient NH3 and NH2OH synthesis across different scenarios. Notably, dual-site heterostructure catalyst exhibits almost 100% NH3-Faradaic Efficiency (FENH3) across a wide nitrate concentration range, reaching a maximum NH3 yield of 10.27 mmol h−1 cm−2. The simultaneous NH3 synthesis-recovery system maintains almost 100% FENH3 and NH3 recovery efficiency over 120 h, accompanied by long-term durability and negligible performance degradation. Additionally, cyclopentanone-mediated NIRR process delivers a satisfactory NH2OH-Faradaic Efficiency (83.48%), and the assembled zinc-nitrate battery achieves a high peak power density (57.6 mW cm−2). The microscopic mechanism of nitrate-to-ammonia electrosynthesis remains ambiguous given the complex dynamic catalytic interface. Here, the authors report a three-step synergistic mechanism that enhances the interaction among interfacial H2O transport, *H generation, and *NOx hydrogenation.
Li et al. (Tue,) studied this question.