Boron Nanosheet: An Elemental Two-Dimensional (2D) Material for Ambient Electrocatalytic N2‑to-NH3 Fixation in Neutral Media

• Published in: ACS catalysis Vol. 9; no. 5; pp. 4609 - 4615
• Main Authors: Zhang, Xiaoxue, Wu, Tongwei, Wang, Huanbo, Zhao, Runbo, Chen, Hongyu, Wang, Ting, Wei, Peipei, Luo, Yonglan, Zhang, Yanning, Sun, Xuping
• Format: Journal Article
• Language: English; Japanese
• Published: American Chemical Society 03.05.2019
• Subjects: elemental 2D material; density functional theory calculations; N2 reduction reaction; boron nanosheet; neutral electrolyte
• DOI: 10.1021/acscatal.8b05134
• ISSN: 2155-5435

The Haber–Bosch process for industrial NH3 production suffers from harsh reaction conditions and serious CO2 emission. Electrochemical N2 reduction offers a carbon-neutral alternative for more energy-saving NH3 synthesis but requires active electrocatalysts for the N2 reduction reaction (NRR). In this Letter, boron nanosheet (BNS) is proposed as an elemental two-dimensional (2D) material to effectively catalyze the NRR toward NH3 synthesis with excellent selectivity. When tested in 0.1 M Na2SO4, such BNS catalyst attains a high Faradaic efficiency of 4.04% and a large NH3 yield of 13.22 μg h–1 mgcat –1 at −0.80 V vs reversible hydrogen electrode, with strong electrochemical durability. Density functional theory calculations suggest that the B atoms of both oxidized and H-deactivated BNS can catalyze the NRR more effectively than clean BNS, and the rate-determining step is the desorption process of the second NH3 gas.