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Abstract A glut of dinitrogen‐derived ammonia (NH₃) over the past century has resulted in a heavily imbalanced nitrogen cycle and consequently, the large‐scale accumulation of reactive nitrogen such as nitrates in our ecosystems has led to detrimental environmental issues. Electrocatalytic upcycling of waste nitrogen back into NH₃holds promise in mitigating these environmental impacts and reducing reliance on the energy‐intensive Haber–Bosch process. Herein, we report a high‐performance electrolyzer using an ultrahigh alkalinity electrolyte, NaOH−KOH−H₂O, for low‐cost NH₃electrosynthesis. At 3,000 mA/cm², the device with a Fe−Cu−Ni ternary catalyst achieves an unprecedented faradaic efficiency (FE) of 92.5±1.5 % under a low cell voltage of 3.83 V; whereas at 1,000 mA/cm², an FE of 96.5±4.8 % under a cell voltage of only 2.40 V was achieved. Techno‐economic analysis revealed that our device cuts the levelized cost of ammonia electrosynthesis by ~40 % ($30.68 for Fe−Cu−Ni vs. $48.53 for Ni foam per kmol‐NH₃). The NaOH−KOH−H₂O electrolyte together with the Fe−Cu−Ni ternary catalyst can enable the high‐throughput nitrate‐to‐ammonia applications for affordable and scalable real‐world wastewater treatments. 

Abstract A glut of dinitrogen‐derived ammonia (NH₃) over the past century has resulted in a heavily imbalanced nitrogen cycle and consequently, the large‐scale accumulation of reactive nitrogen such as nitrates in our ecosystems has led to detrimental environmental issues. Electrocatalytic upcycling of waste nitrogen back into NH₃holds promise in mitigating these environmental impacts and reducing reliance on the energy‐intensive Haber–Bosch process. Herein, we report a high‐performance electrolyzer using an ultrahigh alkalinity electrolyte, NaOH−KOH−H₂O, for low‐cost NH₃electrosynthesis. At 3,000 mA/cm², the device with a Fe−Cu−Ni ternary catalyst achieves an unprecedented faradaic efficiency (FE) of 92.5±1.5 % under a low cell voltage of 3.83 V; whereas at 1,000 mA/cm², an FE of 96.5±4.8 % under a cell voltage of only 2.40 V was achieved. Techno‐economic analysis revealed that our device cuts the levelized cost of ammonia electrosynthesis by ~40 % ($30.68 for Fe−Cu−Ni vs. $48.53 for Ni foam per kmol‐NH₃). The NaOH−KOH−H₂O electrolyte together with the Fe−Cu−Ni ternary catalyst can enable the high‐throughput nitrate‐to‐ammonia applications for affordable and scalable real‐world wastewater treatments. 

Abstract Surface ligands play an important role in shape‐controlled growth and stabilization of colloidal nanocrystals. Their quick removal tends to cause structural deformation and/or aggregation to the nanocrystals. Herein, we demonstrate that the surface ligand based on poly(vinylpyrrolidone) (PVP) can be slowly removed from Pd nanosheets (NSs, 0.93±0.17 nm in thickness) by simply aging the colloidal suspension. The aged Pd NSs show well‐preserved morphology, together with significantly enhanced stability toward both e‐beam irradiation and electrocatalysis (e.g., ethanol oxidation). It is revealed that the slow desorption of PVP during aging forces the re‐exposed Pd atoms to reorganize, facilitating the surface to transform from being nearly perfect to defect‐rich. The resultant Pd NSs with abundant defects no longer rely on surface ligand to stabilize the atomic arrangement and thus show excellent structural and electrochemical stability. This work provides a facile and effective method to maintain the integrity of colloidal nanocrystals by slowly removing the surface ligand.