Kuang Min, Wang Yu, Fang Wei, Tan Huiteng, Chen Mengxin, Yao Jiandong, Liu Chuntai, Xu Jianwei, Zhou Kun, Yan Qingyu
School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.
Environmental Process Modelling Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 CleanTech Loop, Singapore, 637141, Singapore.
Adv Mater. 2020 Jul;32(26):e2002189. doi: 10.1002/adma.202002189. Epub 2020 May 25.
A facile pathway of the electrocatalytic nitrogen oxidation reaction (NOR) to nitrate is proposed, and Ru-doped TiO /RuO (abbreviated as Ru/TiO ) as a proof-of-concept catalyst is employed accordingly. Density functional theory (DFT) calculations suggest that Ru can function as the main active center for the NOR process. Remarkably doping Ru into the TiO lattice can induce an upshift of the d-band center of the Ru site, resulting in enhanced activity for accelerating electrochemical conversion of inert N to active NO*. Overdoping of Ru ions will lead to the formation of additional RuO on the TiO surface, which provides oxygen evolution reaction (OER) active sites for promoting the redox transformation of the NO* intermediate to nitrate. However, too much RuO 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 g (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/TiO catalyst (with the hybrid composition of Ru Ti O and extra RuO by 2.79 wt% Ru addition amount) in 0.1 m Na SO electrolyte.
提出了一种将电催化氮氧化反应（NOR）转化为硝酸盐的简便途径，并相应地采用了Ru掺杂的TiO₂/RuO₂（简称为Ru/TiO₂）作为概念验证催化剂。密度泛函理论（DFT）计算表明，Ru³⁺可作为NOR过程的主要活性中心。值得注意的是，将Ru掺杂到TiO₂晶格中会导致Ru位点的d带中心上移，从而增强了将惰性N电化学转化为活性NO的活性。Ru离子的过度掺杂会导致在TiO₂表面形成额外的RuO₂，这为促进NO中间体向硝酸盐的氧化还原转化提供了析氧反应（OER）活性位点。然而，由于OER过程占主导，催化剂中过多的RuO₂对NOR的选择性和法拉第效率都不利。实验上，Ru/TiO₂催化剂（Ru₂Ti₂O₅的混合组成以及通过添加2.79 wt% Ru产生的额外RuO₂）在0.1 m Na₂SO₄电解液中实现了可观的硝酸盐产率161.9 µmol h⁻¹ g⁻¹（此外，在50小时内总硝酸盐产量为47.9 µg）和最高硝酸盐法拉第效率26.1%。
