High-efficiency electrocatalytic NO reduction to NH<sub>3</sub>by nanoporous VN
Defeng Qi, Fang Lv, Tianran Wei, Mengmeng Jin, Ge Meng, Shusheng Zhang, Qian Liu, Wenxian Liu, Dui Ma, Mohamed S. Hamdy, Jun Luo, Xijun Liu
Abstract
Electrocatalytic NO reduction reaction to generate NH<sub>3</sub> under ambient conditions offers an attractive alternative to the energy-extensive Haber–Bosch route; however, the challenge still lies in the development of cost-effective and high-performance electrocatalysts. Herein, nanoporous VN film is first designed as a highly selective and stable electrocatalyst for catalyzing reduction of NO to NH<sub>3</sub> with a maximal Faradaic efficiency of 85% and a peak yield rate of 1.05 × 10<sup>–7</sup> mol·cm<sup>–2</sup>·s<sup>–1</sup> (corresponding to 5,140.8 μg·h<sup>–1</sup>·mg<sub>cat.</sub><sup>–1</sup>) at –0.6 V vs. reversible hydrogen electrode in acid medium. Meanwhile, this catalyst maintains an excellent activity with negligible current density and NH<sub>3</sub> yield rate decays over 40 h. Moreover, as a proof-of-concept of Zn–NO battery, it delivers a high power density of 2.0 mW·cm<sup>–2</sup> and a large NH<sub>3</sub> yield rate of 0.22 × 10<sup>–7</sup> mol·cm<sup>–2</sup>·s<sup>–1</sup> (corresponding to 1,077.1 μg·h<sup>–1</sup>·mg<sub>cat.</sub><sup>–1</sup>), both of which are comparable to the best-reported results. Theoretical analyses confirm that the VN surface favors the activation and hydrogenation of NO by suppressing the hydrogen evolution. This work highlights that the electrochemical NO reduction is an eco-friendly and energy-efficient strategy to produce NH<sub>3</sub>.