Enhanced photo-Fenton degradation of tetracycline using TiO2-coated α-Fe2O3 core–shell heterojunction

Zheng, Xiaogang; Fu, Wendi; Kang, Fuyan; Peng, Hao; Wen, Jing

doi:10.1016/j.jiec.2018.07.024

Cited by 93 publications

(23 citation statements)

References 69 publications

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“…The degradation efficiency retention compared to the first usage is only 59.6% and 66.7% for TiO 2 @400-Fe 2 O 3 and TiO 2 @800-Fe 2 O 3 , respectively. It may be ascribed to the fact that stability of Fe 2 O 3 during photocatalytic reactions is reduced due to photo-corrosion 42,65 . ALD coatings have been widely used as surface protection layer to protect active materials from photo-corrosion 53,54 .…”

Section: Methodsmentioning

confidence: 99%

Enhanced visible light photocatalytic activity of Fe2O3 modified TiO2 prepared by atomic layer deposition

Cao

Zhao

et al. 2020

Sci Rep

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In this work, commercial anatase TiO 2 powders were modified using ultrathin Fe 2 o 3 layer by atomic layer deposition (ALD). The ultrathin Fe 2 o 3 coating having small bandgap of 2.20 eV can increase the visible light absorption of tio 2 supports, at the meantime, Fe 2 o 3 /tio 2 heterojunction can effectively improve the lifetime of photogenerated electron-hole pairs. Results of ALD Fe 2 o 3 modified TiO 2 catalyst, therefore, showed great visible light driven catalytic degradation of methyl orange compared to pristine tio 2. A 400 cycles of ALD Fe 2 o 3 (~ 2.6 nm) coated TiO 2 powders exhibit the highest degradation efficiency of 97.4% in 90 min, much higher than pristine TiO 2 powders of only 12.5%. Moreover, an ultrathin ALD Al 2 o 3 (~ 2 nm) was able to improve the stability of Fe 2 o 3-tio 2 catalyst. These results demonstrate that ALD surface modification with ultrathin coating is an extremely powerful route for the applications in constructing efficient and stable photocatalysts. A rapid industrial development driven by unsustainable technology advances can cause plenty of industrial sewage, spreading chemical hazards into water resources. As a result, water pollution has emerged as one of the most serious environmental issues worldwide 1-4. Photocatalytic oxidation technology has shown great prospects in removing the toxic and harmful contaminants in aqueous environment 5-7. Semiconductors (e.g. TiO 2 , ZnO, SnO 2) have been widely researched for organic pollutant degradation, however, the large band gap hinders their practical applications 8-12. For example, TiO 2 with band gap of 3.2 eV can only absorb the ultraviolet light, accounting for only 4-5% of entire solar spectrum 13. Therefore, various visible light sensitive photocatalysts has also been widely explored, such as g-C 3 N 4 , BiVO 4 , CdSe, Bi 2 WO 6 14-19. On the other hand, TiO 2 is recognized as one of the excellent materials owning to its good inertness, eco-friendly, low cost, strong oxidizing power, and long-term stability against photo and chemical corrosion 9,13,20-22. Thus, plenty of works have been made to extend the absorption spectrum of TiO 2 to visible light so to make a full use of solar spectrum. Several different approaches can be employed, including doping 23-26 and coupling with small band gap semiconductors or metals 27-30. Small band gap semiconductors not only increase the absorption of visible light but also inhibit photogenerated electrons-holes recombination when constructed as a semiconductor/semiconductor heterojunction structure, thus improving the photocatalytic performance dramatically 31. Therefore, various TiO 2 based heterojunction photocatalysts have been proposed for visible light photocatalysis, including NiO/TiO 2 32,33

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Section: Methodsmentioning

confidence: 99%

Enhanced visible light photocatalytic activity of Fe2O3 modified TiO2 prepared by atomic layer deposition

Cao

Zhao

et al. 2020

Sci Rep

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“…In another study, the core-shell structured α-Fe 2 O 3 (with TiO 2 shell of around 15 nm) exhibited 100% TC removal in 90 min. [41]. The degradation improvement was ascribed to the addition of H 2 O 2 in the system, which generated more ROS than by the common photocatalytic mechanisms described above [41].…”

Section: Tio 2 /Fe 2 Omentioning

confidence: 96%

“…[41]. The degradation improvement was ascribed to the addition of H 2 O 2 in the system, which generated more ROS than by the common photocatalytic mechanisms described above [41]. Hence, the contribution of H 2 O 2 in such a system can be described through restraining e − /h + recombination and increasing HO• generation in the system, as in Equation 1 [42,43].…”

Section: Tio 2 /Fe 2 Omentioning

confidence: 99%

“…[41]. The degradation improvement was ascribed to the addition of H2O2 in the system, which generated more ROS than by the common photocatalytic mechanisms described above [41]. Hence, The photocatalytic degradation of the pharmaceutical tetracycline (TC) and its derivatives, such as oxytetracycline (OTC), using TiO 2 /Fe 2 O 3 materials has also been reported.…”

Section: Tio 2 /Fe 2 Omentioning

confidence: 99%

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Recent Achievements in Development of TiO2-Based Composite Photocatalytic Materials for Solar Driven Water Purification and Water Splitting

et al. 2020

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Clean water and the increased use of renewable energy are considered to be two of the main goals in the effort to achieve a sustainable living environment. The fulfillment of these goals may include the use of solar-driven photocatalytic processes that are found to be quite effective in water purification, as well as hydrogen generation. H2 production by water splitting and photocatalytic degradation of organic pollutants in water both rely on the formation of electron/hole (e−/h+) pairs at a semiconducting material upon its excitation by light with sufficient photon energy. Most of the photocatalytic studies involve the use of TiO2 and well-suited model compounds, either as sacrificial agents or pollutants. However, the wider application of this technology requires the harvesting of a broader spectrum of solar irradiation and the suppression of the recombination of photogenerated charge carriers. These limitations can be overcome by the use of different strategies, among which the focus is put on the creation of heterojunctions with another narrow bandgap semiconductor, which can provide high response in the visible light region. In this review paper, we report the most recent advances in the application of TiO2 based heterojunction (semiconductor-semiconductor) composites for photocatalytic water treatment and water splitting. This review article is subdivided into two major parts, namely Photocatalytic water treatment and Photocatalytic water splitting, to give a thorough examination of all achieved progress. The first part provides an overview on photocatalytic degradation mechanism principles, followed by the most recent applications for photocatalytic degradation and mineralization of contaminants of emerging concern (CEC), such as pharmaceuticals and pesticides with a critical insight into removal mechanism, while the second part focuses on fabrication of TiO2-based heterojunctions with carbon-based materials, transition metal oxides, transition metal chalcogenides, and multiple composites that were made of three or more semiconductor materials for photocatalytic water splitting.

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“…Photocatalysis, as a potential route to relieving environmental and energy issues, has been intensively applied for pollutant degradation [1][2][3][4], water splitting [5][6][7], and solar energy conversion [8][9][10][11]. As a typical metal sulfide, ZnS, which has a large band gap (3.6~3.8 eV), exhibits excellent photocatalytic capacity, owing to its strong oxidation and high negative potentials of excited electrons [12,13].…”

Section: Introductionmentioning

confidence: 99%

N-Doped Carbon-Coated ZnS with Sulfur-Vacancy Defect for Enhanced Photocatalytic Activity in the Visible Light Region

et al. 2019

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In this work, N-doped carbon-coated ZnS with a sulfur-vacancy defect (ZnS@N-C) was performed for the visible-light-driven photodegradation of tetracycline hydrochloride (TCH). The obtained ZnS@N-C exhibited enhanced photocatalytic activity compared with ZnS for TCH removal. Among these ZnS@N-C composites, ZnS@N-C-3 with N-doped content of 3.01% (100 nm) presented the best visible-light photocatalytic activity and superior long-term photocatalytic stability after five cycle times for TCH removal in the visible light region. This may be ascribed to the interface between the N-doped carbon shell and ZnS with a sulfur-vacancy defect for efficient charge transfer and the restrained recombination of charge carriers. Electron spin resonance (ESR) results indicate that the ·O 2 radical plays a crucial role in the enhanced photocatalytic activity of ZnS@N-C-3. Nanomaterials 2019, 9, 1657 2 of 13 composites between carbon and semiconductors. To further enhance the electron transfer and extend the visible light harvesting region, carbon doped with N atoms can adjust the work function of carbon and induce charge delocalization [23-26]. Hsu et al. have reported that sandwich-like hydrogenated C-doped anatase TiO 2 nanocrystals/N-doped carbon dots@layer/rutile TiO 2 nanorod arrays have exhibited efficient photoelectron-chemical activity of water oxidation [27]. This may be attributed to the N-doped carbon dots being the photosensitizer of long wavelength light-harvesting and the N-doped carbon layer being the conductive layer of charge transport toward the current collector. Wang et al. have also confirmed that N-doped carbon dots/g-C 3 N 4 can enhance visible-light photo-degradation activity for indomethacin due to the efficient charge separation and band gap narrowing of N-doped carbon dots [28]. Core-shell structured ZnO@N-doped carbon can efficiently adsorb and photodegrade methylene blue in the visible light region [29]. Electrons generated from nitrogen are transferred from the N-doped carbon surface to adsorbed oxygen, forming reactive radicals in the photocatalytic system [30-34]. In addition, surface polarity of N-doped carbon can promote dispersion in aqueous solution. However, few works have focused on the enhanced photocatalytic activity of ZnS with sulfur-vacancy defects using N-doped carbon coating. This work focuses on the synthesis of ZnS with an N-doped carbon coating (ZnS@N-C) and its sulfur-vacancy effect on visible-light photocatalytic activity for the removal of tetracycline hydrochloride (TCH). Reported photocatalysts such as CuInS 2 /Mg(OH) 2 [35], ZnIn 2 S 4 /BiPO 4 [36], AgBr/Bi 2 WO 6 [37], BiOI/g-C 3 N 4 /CeO 2 [38], and TiO 2 / BiOCl [39] are efficient heterojunctions for the visible-light-driven degradation of TCH. Differently from these compositions, N-doped carbon serves as the electron capture, facilitating the separation of electron-hole pairs. In this strategy, N-doped carbon is generated from the decomposition of cyanamide and coated on the surface of ZnS nano-particles, which are further tr...

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Enhanced photo-Fenton degradation of tetracycline using TiO2-coated α-Fe2O3 core–shell heterojunction

Cited by 93 publications

References 69 publications

Enhanced visible light photocatalytic activity of Fe2O3 modified TiO2 prepared by atomic layer deposition

Enhanced visible light photocatalytic activity of Fe2O3 modified TiO2 prepared by atomic layer deposition

Recent Achievements in Development of TiO2-Based Composite Photocatalytic Materials for Solar Driven Water Purification and Water Splitting

N-Doped Carbon-Coated ZnS with Sulfur-Vacancy Defect for Enhanced Photocatalytic Activity in the Visible Light Region

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