Mesostructures Engineering to Promote Selective Nitrate‐to‐Ammonia Electroreduction

Abstract

AbstractThe 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 (FENH3) 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 FENH3 of 92.4%.