Mesostructures Engineering to Promote Selective Nitrate‐to‐Ammonia Electroreduction

Abstract The electroreduction of nitrate into green ammonia (NO 3 − ‐to‐NH 3 ) in aqueous solution represents a sustainable route applicable to green NH 3 electrosynthesis and nitrogen balance. However, the NO 3 − ‐to‐NH 3 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 NO 3 − ‐to‐NH 3 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 NO 3 − ‐to‐NH 3 performance with high NH 3 Faradaic efficiency (FE NH3 ) of 95.2%, superior NH 3 yield rate of 17.7 mg h −1 mg −1 , impressive NH 3 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 NO 3 − ‐to‐NH 3 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 NO 3 − into NH 3 through an 8e − reaction pathway. Meanwhile,1D PdCuAg MTs are practically explored in a Zn‐NO 3 − battery, delivering a superior NH 3 yield rate of 25.85 µmol h −1 cm −2 and a high FE NH3 of 92.4%.