Electrocatalytic N2-to-NH3 conversion with high faradaic efficiency enabled using a Bi nanosheet array

• Published in: Chemical communications (Cambridge, England) Vol. 55; no. 36; pp. 5263 - 5266
• Main Authors: Zhang, Rong, Ji, Lei, Kong, Wenhan, Wang, Huanbo, Zhao, Runbo, Chen, Hongyu, Li, Tingshuai, Li, Baihai, Luo, Yonglan, Sun, Xuping
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2019
• Subjects: Ammonia; Arrays; bismuth; Catalysis; Catalysts; chemical reactions; copper; copper nanoparticles; Current efficiency; Density functional theory; Efficiency; electrochemistry; Electrodes; foil; hydrochloric acid; hydrogen; Hydrogen evolution; hydrogen production; Metal foils; Nanosheets; nitrogen; Noble metals; Reduction
• ISSN: 1359-7345; 1364-548X; 1364-548X
• DOI: 10.1039/c9cc01703h

Electrocatalytic N2 reduction represents a promising alternative to the conventional Haber–Bosch process for ambient N2-to-NH3 fixation, but it is severely challenged by competitive hydrogen evolution, which limits the current efficiency for NH3 formation. In this work, a nanosheet array of metallic Bi, an environmentally benign elemental substance previously predicted theoretically to have low hydrogen-evolving activity, is proposed as a superior catalyst for N2 reduction electrocatalysis. Electrochemical tests show that the Bi nanosheet array on Cu foil as a stable 3D catalyst electrode achieves a high faradaic efficiency of 10.26% with an NH3 yield rate of 6.89 × 10−11 mol s−1 cm−2 at −0.50 V vs. the reversible hydrogen electrode in 0.1 M HCl, rivalling the performances of most reported noble-metal-free catalysts operating in acids. Density functional theory calculations suggest that Bi effectively activates the N≡N bond and the alternating mechanism is energetically favourable.