Mesostructures Engineering to Promote Selective Nitrate‐to‐Ammonia Electroreduction

Abstract The electroreduction of nitrate into green ammonia (NO₃⁻‐to‐NH₃) in aqueous solution represents a sustainable route applicable to green NH₃ electrosynthesis and nitrogen balance. However, the NO₃⁻‐to‐NH₃ electroreduction undergoes a complex eight electron (8e⁻) transfer pathway and results in unsatisfying activity and selectivity. Here, mesostructures engineering is presented as a new and robust design strategy for producing high‐performance multimetallic electrocatalysts that remarkably promote selective NO₃⁻‐to‐NH₃ electroreduction. 1D PdCuAg mesoporous nanotubes (MTs) are facilely prepared by a one‐step galvanic replacement‐assisted surfactant‐templating method in an aqueous solution. The electrocatalyst shows remarkable NO₃⁻‐to‐NH₃ performance with high NH₃ Faradaic efficiency (FE_NH3) of 95.2%, superior NH₃ yield rate of 17.7 mg h⁻¹ mg⁻¹, impressive NH₃ energy efficiency of 29.8%, and outstanding stability (50 cycles), all of which are much better than the performance of counterpart electrocatalysts. The promotion of NO₃⁻‐to‐NH₃ performance comes from the electron‐rich surface and nanoconfinement microenvironment of mesostructured synergies that enrich nanozyme‐like chemisorption of key intermediates and thus facilitates electroreduction of NO₃⁻ into NH₃ through an 8e⁻ reaction pathway. Meanwhile,1D PdCuAg MTs are practically explored in a Zn‐NO₃⁻ battery, delivering a superior NH₃ yield rate of 25.85 µmol h⁻¹ cm⁻² and a high FE_NH3 of 92.4%.