Ru doped NiMoO4 nanoarray as a high-efficiency electrocatalyst for nitrite reduction to ammonia

• Published in: Journal of colloid and interface science 2024-05, Vol.661, p.401-408
• Main Authors: Wang, Guoguo, Chen, Qiuyue, Zhang, Jing, An, Xuguan, Liu, Qian, Xie, Lisi, Yao, Weitang, Sun, Xuping, Kong, Qingquan
• Format: Article
• Language: English
• Subjects: Ammonia synthesis; Density functional theory; NO2– reduction reaction; Ru-NiMoO4 nanosheet
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2024.01.195

We report on Ru-doped self-supported honeycomb nickel molybdate nanoflakes (Ru-NiMoO4/NF) with abundant OV on Ni foam and its application in both electrocatalytic NO2–RR and Zn-NO2– battery. The catalytic activity of Ru-NiMoO4/NF was significantly enhanced due to the Ru doping and the existence of oxygen vacancies, achieving high Faraday efficiency of 95.56 ± 0.72% and large ammonia yield of 17192.52 ± 1136.64 μg h−1 cm−2 at –0.6V vs. RHE in 0.5 M Na2SO4 and 0.1 M NO2– solution, as well as preferable long-term stability. In addition, it was verified that Zn-NO2– battery with Ru-NiMoO4/NF as cathode delivers a good energy supply (13.87 mW cm−2), as well as simultaneously ammonium yield of 1524.74 μg h−1 cm−2 and Faradaic efficiency of 96.15% at 15 mA cm−2. [Display omitted] The electrocatalytic reduction of nitrite to recyclable ammonia (NH3) is essential to maintain nitrogen balance and meet growing energy requirements. Herein, we report that Ru doped honeycomb NiMoO4 nanosheet with copious oxygen vacancies grown on nickel foam substrate has been prepared by a facile hydrothermal synthesis and immersion process, which can act as an efficient electrocatalyst for NH3 synthesis by reduction of nitrite. By optimizing the concentration of RuCl3 solution, 0.01Ru-NiMoO4/NF possesses excellent NO2−RR performance with NH3 yield of 20249.17 ± 637.42 μg h−1 cm−2 at −0.7 V and FE of 95.56 ± 0.72 % at −0.6 V. When assembled into a Zn–NO2− battery, it provides a remarkable level of power density of 13.89 mW cm−2, outperforming the performance of virtually all previous reports. The efficient adsorption and activation of NO2− over Ru-doped NiMoO4 with oxygen vacancy have been verified by density functional theory calculations, as well as the possible reaction pathway.