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Photochemical Transformation Pathways of Nitrates from Photocatalytic NOx Oxidation: Implications for Controlling Secondary Pollutants
Environmental Science & Technology Letters ( IF 8.9 ) Pub Date : 2021-09-01 , DOI: 10.1021/acs.estlett.1c00661
Hong Wang 1 , Kanglu Li 1 , Jieyuan Li 1, 2 , Yanjuan Sun 3 , Fan Dong 1, 2
Affiliation  

Photocatalytic NOx abatement is crucial for the atmospheric environment. Nonetheless, the possible pathway for the conversion of the product (NO3) from photocatalytic NOx oxidation and its impact on sustained NOx removal have been overlooked, which is related to the final environmental benefit. Herein, the elusive NO3 conversion mechanism is revealed via the synergetic application of in situ characterization and theoretical calculation technologies. It is found that the N–O bond in surface NO3 could be activated by NO molecules, arising from the significant overlap of the 2p orbitals between the N in NO and the O in NO3. Then, photogenerated electrons (e) captured by NO drive the transformation of NO3 under light irradiation via the NO3 + NO → 2NO2 route. Additionally, although photogenerated holes (h+) and hydroxyl radicals (•OH) could oxidize NO into NO3, the rate of production of NO3 is much slower than that of photochemical transformation by NO. The results of control experiments show that NO is the key species to trigger the decomposition of surface NO3. This work clarifies the influence of reactants on surface NO3 conversion during photocatalytic NOx oxidation, providing a comprehensive mechanism for the photochemical NO3 conversion pathway.

中文翻译:

光催化 NOx 氧化中硝酸盐的光化学转化途径:对控制二次污染物的影响

光催化氮氧化物减排对大气环境至关重要。尽管如此,光催化NOx氧化产物(NO 3 -)的可能转化途径及其对持续NOx去除的影响却被忽视了,这与最终的环境效益有关。在此,通过原位表征和理论计算技术的协同应用,揭示了难以捉摸的NO 3 -转化机制。发现表面 NO 3 中的 N-O 键可以被 NO 分子激活,这是由于 NO 中的 N 和 NO 3 – 中的 O 之间的 2p 轨道的显着重叠引起的。然后,光生电子(e -) 被 NO 捕获,通过 NO 3 + NO → 2NO 2 路线在光照射下驱动 NO 3 的转化。另外,尽管光生空穴(h +)和羟基自由基(OH•)可以氧化成NO NO 3 -,NO产生的速率3 -比光化学转化的慢得多的NO - 。对照实验结果表明NO -是引发表面NO 3 -分解的关键物质。这项工作阐明了反应物对表面 NO 3 的影响光催化 NOx 氧化过程中的转化,为光化学 NO 3 转化途径提供了综合机制。
更新日期:2021-10-12
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