Atomic Molybdenum for Synthesis of Ammonia with 50% Faradic Efficiency. Issue 15 (12th March 2022)

• Record Type: Journal Article
• Authors: Zhang, Chenhao; Wang, Zhe; Lei, Jincheng; Ma, Lu; Yakobson, Boris I.; Tour, James M.
• Is Part Of: Small. Volume 18:Issue 15(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-12
• Subjects: atomic molybdenum -- electrochemical N 2 reduction reaction -- holey graphene -- nitrogen‐doped graphene -- single‐atom catalysts; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202106327
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: The electrochemical dinitrogen (N2 ) reduction reaction (NRR) under ambient conditions has gained significant interest as an environmentally friendly alternative to the traditional Haber–Bosch process for the synthesis of ammonia (NH3 ). However, up to now, most of the reported NRR electrocatalysts with satisfactory catalytic activities have been hindered by the large overpotential in N2 activation. The preparation of highly efficient Mo‐based NRR electrocatalyst in acidic electrolytes under ambient conditions is demonstrated here, consisting of stabilized single Mo atoms anchored on holey nitrogen‐doped graphene synthesized through a convenient potassium‐salt‐assisted activation method. At −0.05 V versus a reversible hydrogen electrode (RHE), an electrode consisting of the resultant electrocatalyst immobilized on carbon fiber paper can attain an exceptional Faradaic efficiency of 50.2% and a NH3 yield rate of 3.6 µg h −1 mgcat −1 with low overpotentials. Density functional theory calculations further unveil that compared to the original graphene without holes, the edge coordinated Mo atoms and the existence of vacancies on holey graphene lower the overpotential of N2 reduction, thereby promoting the NRR catalytic activity. This work could provide new guidelines for future designs in single‐atom catalysis that would be beneficial to ambient N2 fixation, and replacement of classical synthesis processes that are very energy‐intensive. Abstract : The electrochemical dinitrogen reduction reaction provides a potential alternative to the traditional Haber–Bosch process. Using a defect engineering strategy, Mo single atoms with small coordination numbers are anchored on the edges of holey nitrogen graphene. Theoretical and experimental results show this structure can successfully reduce the reaction barrier to break the dinitrogen triple bond and achieve high energy efficiency.