In Situ Synthesis of CuxO/N Doped Graphdiyne with Pyridine N Configuration for Ammonia Production via Nitrate Reduction

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-08, Vol.20 (33), p.e2310467-n/a
• Main Authors: Li, Jian, Valenza, Roberto, Haussener, Sophia
• Format: Article
• Language: English
• Subjects: Ammonia; ammonia production; Anion exchanging; Chemical synthesis; Configurations; electrocatalysis; graphdiyne; Hydrogen evolution reactions; Industrial applications; N doping; nitrate reduction; Nitrates; Nitrogen dioxide; Pyridines; Reaction kinetics; Room temperature; Synergistic effect; Wastewater treatment
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202310467

Electroreduction of nitrate to ammonia provides an interesting pathway for wastewater treatment and valorization. Cu‐based catalysts are active for the conversion of NO3− to NO2− but suffer from an inefficient hydrogenation process of NO2−. Herein, CuxO/N‐doped graphdiyne (CuxO/N‐GDY) with pyridine N configuration are in situ prepared in one pot. Benefiting from the synergistic effect of pyridinic N in GDY and CuxO, the prepared CuxO/N‐GDY tested in a commercial H‐cell achieved a faradaic efficiency of 85% toward NH3 at ‐0.5 V versus RHE with a production rate of 340 µmol h−1 mgcat−1 in 0.1 M KNO3. When integrating the CuxO/N‐GDY in an anion exchange membrane flow electrolyzer, a maximum Faradaic efficiency of 89% is achieved at a voltage of 2.3 V and the production rate is 1680 µmol h−1 mgcat−1 at 3.3 V in 0.1 M KNO3 at room temperature. Operation at 40 °C further promoted the overall reaction kinetics of NO3− to NH3, but penalized its selectivity with respect to hydrogen evolution reaction. The high selectivity and production rate in this device configuration demonstrate its potential for industrial application. CuxO/N‐doped graphdiyne with pyridine N configuration are in situ prepared in one pot. Pyridinic N in GDY and CuxO synergistically allowed to achieve NH3 faradaic efficiencies greater than 85% both in a commercial H‐cell and an anion exchange membrane (AEM) flow electrolyzer. The high selectivity and production rate in this device configuration demonstrate its potential for industrial application.