@article {JI2021129605,
	title = {Experimental evidences and theoretical calculations on phenanthrene degradation in a solar-light-driven photocatalysis system using silica aerogel supported TiO2 nanoparticles: Insights into reactive sites and energy evolution},
	journal = {Chemical Engineering Journal},
	volume = {419},
	year = {2021},
	pages = {129605},
	abstract = {Quantitative identification on reactive sites of target organic molecule during photocatalysis can help to get deep insight into the pollutant degradation pathway and energy evolution process. In this study, a new class of silica aerogel supported TiO2 (TiO2/SiO2) photocatalysts were fabricated via a two-step approach, and applied for adsorption and photocatalytic degradation of phenanthrene. Anatase crystalline structure was formed upon calcination at 400 and 600~{\textdegree}C, while mixed crystal interphases of anatase and rutile were generated at 800~{\textdegree}C (anatase:rutile~=~0.67:0.33). The higher calcination temperature resulted in better crystallinity of TiO2, higher photocatalytic activity, and reduced adsorption affinity toward phenanthrene. TiO2/SiO2-800 (TiO2/SiO2 calcined at 800~{\textdegree}C) showed minimal phenanthrene uptake (~5.2\%) but the strongest photocatalytic activity, and it was able to completely degrade phenanthrene within 3~h. The SiO2 aerogel component in the composite enabled the pre-concentration of phenanthrene on the photoactive sites, while the nanoscale mixed-phases of anatase and rutile of TiO2/SiO2-800 act as an efficient transfer medium for photo-induced charge carriers. Moreover, the formed Ti{\textendash}O{\textendash}Si linkage in TiO2/SiO2-800 induced formation of Ti3+ under solar light irradiation, promoting photoexcited electron trap and separation of electron-hole pairs. Based on the degraded phenanthrene intermediates/products, theoretical calculations according to the density functional theory (DFT) reveal that the atoms of phenanthrene with high electrophilic Fukui index (f -) are the most reactive sites towards the radicals. Potential energy surface profile for phenanthrene degradation further reveals the intermediates energy evaluation via radicals attack.},
	keywords = {Density functional theory, Organic pollutants, Photocatalysis, Reactive sites, TiO nanoparticles},
	issn = {1385-8947},
	doi = {http://doi.org/10.1016/j.cej.2021.129605},
	url = {http://www.sciencedirect.com/science/article/pii/S138589472101192X},
	author = {Ji, Haodong and Liu, Wen and Fengbin Sun and Taobo Huang and Long Chen and Yue Liu and Juanjuan Qi and Chenghan Xie and Zhao, Dongye}
}