Integrated Three-in-one to Boost Nitrate Electroreduction to Ammonia Utilizing a 1D Mesoporous Carbon Cascade Nanoreactor.

The electrochemical reduction of nitrate (NO) offers a promising waste-to-value strategy for synthesizing ammonia (NH), yet it involves a complex multi-interface system with several stages such as mass transport, species enrichment, and interfacial transformation. This complexity necessitates catalysts with diverse structural characteristics across multiple temporal and spatial scales. Herein, a three-in-one nanoreactor system is designed with 1D geometry, open mesochannels, and synergistic active sites for optimized NH synthesis. Guided by finite element simulations, a 1D mesoporous carbon carrier is engineered to create a distinctive microenvironment that enhances NO transfer and adsorption while confining reaction intermediates. Meanwhile, iron single atomic sites (Fe-N SAs) and iron nanoclusters (Fe NCs) are embedded in situ into the carbon carrier, yielding an efficient cascade nanoreactor. This design demonstrates large Faraday efficiencies, rapid NO removal rates, and impressive NH yield rates under both neutral and alkaline conditions. Detailed in situ experimental results and theoretical analysis reveal that Fe-N SAs and Fe NCs can adapt their electronic structures in tandem, allowing the Fe-N SAs to effectively reduce NO and Fe NCs to oxidize HO. As a demonstration, the assembled Zn-NO battery achieves a power density of 20.12 mW cm coupled with excellent rechargeability.