Efficient Nitrate Synthesis via Ambient Nitrogen Oxidation with Ru‐Doped TiO2/RuO2 Electrocatalysts. Issue 26 (25th May 2020)

• Record Type: Journal Article
• Authors: Kuang, Min; Wang, Yu; Fang, Wei; Tan, Huiteng; Chen, Mengxin; Yao, Jiandong; Liu, Chuntai; Xu, Jianwei; Zhou, Kun; Yan, Qingyu
• Is Part Of: Advanced materials. Volume 32:Issue 26(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-05-25
• Subjects: ambient nitrate synthesis -- composite electrocatalysts -- nitrogen fixation -- nitrogen oxidation reaction -- Ru‐doped TiO2; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202002189
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: A facile pathway of the electrocatalytic nitrogen oxidation reaction (NOR) to nitrate is proposed, and Ru‐doped TiO2 /RuO2 (abbreviated as Ru/TiO2 ) as a proof‐of‐concept catalyst is employed accordingly. Density functional theory (DFT) calculations suggest that Ru δ + can function as the main active center for the NOR process. Remarkably doping Ru into the TiO2 lattice can induce an upshift of the d‐band center of the Ru site, resulting in enhanced activity for accelerating electrochemical conversion of inert N2 to active NO*. Overdoping of Ru ions will lead to the formation of additional RuO2 on the TiO2 surface, which provides oxygen evolution reaction (OER) active sites for promoting the redox transformation of the NO* intermediate to nitrate. However, too much RuO2 in the catalyst is detrimental to both the selectivity of the NOR and the Faradaic efficiency due to the dominant OER process. Experimentally, a considerable nitrate yield rate of 161.9 µmol h −1 gcat −1 (besides, a total nitrate yield of 47.9 µg during 50 h) and a highest nitrate Faradaic efficiency of 26.1% are achieved by the Ru/TiO2 catalyst (with the hybrid composition of Ru x Ti y O2 and extra RuO2 by 2.79 wt% Ru addition amount) in 0.1 m Na2 SO4 electrolyte. Abstract : A novel Ru‐doped TiO2 /RuO2 composite catalyst is designed and applied to the electrochemical nitrogen oxidation reaction, which enables the efficient conversion of nitrogen gas to aqueous nitrate under ambient conditions. The optimized Ru‐doped TiO2 /RuO2 catalyst shows a considerable nitrate yield rate of 161.9 µmol h −1 gcat −1 and a highest nitrate Faradaic efficiency of 26.1%.