Defective TiO2−x for High‐Performance Electrocatalytic NO Reduction toward Ambient NH3 Production

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2023-06, Vol.19 (24), p.e2300291-n/a
• Main Authors: Li, Zixiao, Zhou, Qiang, Liang, Jie, Zhang, Longcheng, Fan, Xiaoya, Zhao, Donglin, Cai, Zhengwei, Li, Jun, Zheng, Dongdong, He, Xun, Luo, Yongsong, Wang, Yan, Ying, Binwu, Yan, Hong, Sun, Shengjun, Zhang, Jing, Alshehri, Abdulmohsen Ali, Gong, Feng, Zheng, Yinyuan, Sun, Xuping
• Format: Article
• Language: English
• Subjects: ambient ammonia synthesis; Ammonia; Chemical reduction; Chemical synthesis; Density functional theory; Deoxygenation; Electrocatalysts; Electrolysis; Low concentrations; Nanotechnology; Nitric oxide; nitric oxide (NO) reduction reaction; oxygen vacancies; Protonation; theoretical calculations; TiO 2− x nanoarray; Titanium dioxide
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202300291

Synthesis of green ammonia (NH3) via electrolysis of nitric oxide (NO) is extraordinarily sustainable, but multielectron/proton‐involved hydrogenation steps as well as low concentrations of NO can lead to poor activities and selectivities of electrocatalysts. Herein, it is reported that oxygen‐defective TiO2 nanoarray supported on Ti plate (TiO2−x/TP) behaves as an efficient catalyst for NO reduction to NH3. In 0.2 m phosphate‐buffered electrolyte, such TiO2−x/TP shows competitive electrocatalytic NH3 synthesis activity with a maximum NH3 yield of 1233.2 µg h−1 cm−2 and Faradaic efficiency of 92.5%. Density functional theory calculations further thermodynamically faster NO deoxygenation and protonation processes on TiO2−x (101) compared to perfect TiO2 (101). And the low energy barrier of 0.7 eV on TiO2−x (101) for the potential‐determining step further highlights the greatly improved intrinsic activity. In addition, a Zn‐NO battery is fabricated with TiO2−x/TP and Zn plate to obtain an NH3 yield of 241.7 µg h−1 cm−2 while providing a peak power density of 0.84 mW cm−2. TiO2−x nanoarray on Ti plate acts as an efficient electrocatalyst toward converting nitric oxide to ammonia (NH3) at ambient conditions, achieving a high Faradic efficiency of 92.5% at −0.4 V and a large NH3 yield of up to 1233.2 µg h−1 cm−2 at −0.7 V.