Oxygen Vacancy‐Controlled CuOx/N,Se Co‐Doped Porous Carbon via Plasma‐Treatment for Enhanced Electro‐Reduction of Nitrate to Green Ammonia

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-09, Vol.20 (37), p.e2403253-n/a
• Main Authors: Maeng, Junbeom, Jang, Daehee, Ha, Jungseub, Ji, Junhyuk, Heo, Jaehyun, Park, Yeji, Kim, Subin, Kim, Won Bae
• Format: Article
• Language: English
• Subjects: Ammonia; Bonding strength; Carbon; Catalysts; Chemical reduction; Copper oxides; Design factors; Doping; Electrochemical analysis; green ammonia; heteroatom doping; Hydrogen evolution reactions; nitrate reduction; Nitrates; Oxygen; oxygen vacancies; Performance enhancement; plasma treatment
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202403253

The electrochemical nitrate reduction reaction (NO3RR) is of significance in regards of environmentally friendly issues and green ammonia production. However, relatively low performance with a competitive hydrogen evolution reaction (HER) is a challenge to overcome for the NO3RR. In this study, oxygen vacancy‐controlled copper oxide (CuOx) catalysts through a plasma treatment are successfully prepared and supported on high surface area porous carbon that are co‐doped with N, Se species for its enhanced electrochemical properties. The oxygen vacancy‐increased CuOx catalyst supported on the N,Se co‐doped porous carbon (CuOx‐H/NSePC) exhibited the highest NO3RR performance with faradaic efficiency (FE) of 87.2% and yield of 7.9 mg cm−2 h−1 for the ammonia production, representing significant enhancements of FE and ammonia yield as compared to the un‐doped or the oxygen vacancy‐decreased catalysts. This high performance should be attributed to a significant increase in the catalytic active sites with facilitated energetics from strategies of doping the catalytic materials and weakening the N─O bonding strength for the adsorption of NO3− ions on the modulated oxygen vacancies. This results show a promise that co‐doping of heteroatoms and regulating of oxygen vacancies can be key factors for performance enhancement, suggesting new guidelines for effective catalyst design of NO3RR. Heteroatom co‐doping increases the catalytic active sites and modulates oxygen vacancies on catalyst surfaces weakening the N─O bonding strength for the adsorption of NO3− ions. Consequently, it improves both the catalytic activity and stability of the nitrate reduction reaction (NO3RR) while inhibiting the competitive hydrogen evolution reaction (HER). These effects contribute to the high performance of green ammonia production.