26
|
Zhu Z, Zhu C, Hu C, Liu B. Facile fabrication of BiOIO 3/MIL-88B heterostructured photocatalysts for removal of pollutants under visible light irradiation. J Colloid Interface Sci 2021; 607:595-606. [PMID: 34509734 DOI: 10.1016/j.jcis.2021.08.183] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 08/26/2021] [Accepted: 08/27/2021] [Indexed: 02/04/2023]
Abstract
In this work, a Z-scheme heterojunction of BiOIO3/MIL-88B was constructed via two steps solvothermal method. Various characterization techniques showed that this Z-scheme heterojunction is an effective strategy to promote spatial charge separation, and the catalytic performance was evaluated by degrading simulated organic pollutants. Herein, the BiOIO3/MIL-88B composites exhibited an exceptional removal rate for Reactive Blue 19 and tetracycline hydrochloride (TC) under visible light irradiation, which was approximately 3.28 and 4.22 times higher than the pristine BiOIO3, respectively. Additionally, the analysis of photocatalysis mechanism showed that the active species O2- and OH could strongly affect the degradation of tetracycline hydrochloride (TC) in the studied system. Furthermore, the degradation process of TC was tracked and detected by identifying intermediates produced in the reaction system. It is anticipated that this research can deepen the understanding of BiOIO3/MIL-88B heterojunction structure to remove organic contaminants and provide a strategy for applying photocatalytic technology in the practical industry.
Collapse
|
27
|
Yang W, Yang Z, Shao L, Li S, Liu Y, Xia X. Photocatalytic reduction of Cr(VI) over cinder-based nanoneedle in presence of tartaric acid: Synergistic performance and mechanism. J Environ Sci (China) 2021; 107:194-204. [PMID: 34412782 DOI: 10.1016/j.jes.2021.02.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 06/13/2023]
Abstract
Cr(VI) is a common heavy metal ion, which will seriously harm human body and environment. Therefore, the removal of Cr(VI) has become an attractive topic. In this work, cinder was used as a raw material to synthesize a nanoneedle material: γ-(AlOOH@FeOOH) (γ-Al@Fe). The physicochemical properties of γ-Al@Fe were thoroughly characterized, and its effectiveness as a catalyst for photocatalytic reduction of Cr(VI) was evaluated. The results showed that Cr(VI) could be efficiently reduced by γ-Al@Fe in the presence of tartaric acid (TA) under visible light. The variable factors on the reaction were investigated in detail, and the results showed that under optimal conditions (γ-Al@Fe 0.4 g/L, TA 0.6 g/L, pH 2), Cr(VI) was completely reduced within 7 min. Besides, scavenger experiments and EPR proved that O2• - and CO2• - played a significant role in the photocatalytic reduction of Cr(VI). TA acts as a sacrificial agent to trap the holes and generate strong reducing free radicals: CO2• -. Dissolving O2 could react with electrons to generate O2• -. This work discussed the performance and mechanism of photocatalytic reduction of Cr(VI) in detail, which provided a new idea for the resource utilization of solid waste and the treatment of heavy metal sewage.
Collapse
|
28
|
Wu Y, Zhao X, Huang S, Li Y, Zhang X, Zeng G, Niu L, Ling Y, Zhang Y. Facile construction of 2D g-C 3N 4 supported nanoflower-like NaBiO 3 with direct Z-scheme heterojunctions and insight into its photocatalytic degradation of tetracycline. JOURNAL OF HAZARDOUS MATERIALS 2021; 414:125547. [PMID: 33676258 DOI: 10.1016/j.jhazmat.2021.125547] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 02/10/2021] [Accepted: 02/25/2021] [Indexed: 06/12/2023]
Abstract
Photocatalytic oxidation using solar energy is a promising green technology to degrade antibiotic contaminants. Herein, a 2D g-C3N4 supported nanoflower-like NaBiO3 with direct Z-scheme heterojunction was synthesized via a facile hydrothermal approach, and the photocatalytic performance of g-C3N4/NaBiO3 was remarkable better than that of g-C3N4 and NaBiO3 for tetracycline degradation under visible light. Photoinduced electrons accumulated on the conduction band of g-C3N4 and holes gathered on the valence band of NaBiO3, which was more suitable for generating superoxide and hydroxyl radicals. Meanwhile, the built-in electric field between g-C3N4 and NaBiO3 was proved by their different work functions based on DFT calculations, which enhanced the charges separation. The formed radicals were determined by ESR, and their role in the degradation of tetracycline was examined by the active species trapping test. Moreover, the sites attacked by free radicals and degradation pathways for tetracycline were inferred by the results of Gaussian 09 program and HPLC-MS. The effects of water matrix and three other organic contaminants was further studied for actual use evaluation. Importantly, the prepared g-C3N4/NaBiO3 showed stable photodegradation activity for eight cycles. This work not only provides a promising photocatalyst, but also gets insight into the photocatalytic removal of tetracycline.
Collapse
|
29
|
Mohammad A, Khan ME, Cho MH, Yoon T. Graphitic‑carbon nitride based mixed-phase bismuth nanostructures: Tuned optical and structural properties with boosted photocatalytic performance for wastewater decontamination under visible-light irradiation. NANOIMPACT 2021; 23:100345. [PMID: 35559846 DOI: 10.1016/j.impact.2021.100345] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 07/20/2021] [Accepted: 08/02/2021] [Indexed: 06/15/2023]
Abstract
To enhance the activities of advanced semiconductor photocatalysts, the charge carriers must be separated effectively. One strategy for achieving this is the use of heterogeneous structures, which can be prepared by hydrothermal synthesis and post-synthetic thermal and ultrasonic treatment. Herein, we report a mixed-phase composite of basic bismuth nitrate/pentabismuth heptaoxide nitrate (PC) prepared by hydrothermal synthesis under basic conditions and post-synthetic thermal treatment. In addition, sulfur-doped-graphitic carbon nitride (S-g-C3N4) was prepared and combined with PC in different ratios, denoted as PC-1, PC-2, and PC-3, using sonication-assisted treatment. The characterization of these catalysts confirmed the formation of mixed basic bismuth nitrate/pentabismuth heptaoxide nitrate phases and the composite nanostructure. The developed nanostructure showed interesting morphological features, for example, layered sheets of S-g-C3N4. The prepared PCs were tested for their visible light responsiveness for the photocatalytic degradation of a representative organic dye (Rhodamine B). We found that the modified photocatalysts showed superior activity to that of pristine PC. The optimal photocatalyst (PC-3) was also used to degrade methylene blue and Congo red, achieving 99% degradation. Thus, we present not only an efficient photocatalyst but also insights into the post-synthetic modification of basic bismuth nitrate/pentabismuth heptaoxide nitrate with stable carbon-based nanostructures.
Collapse
|
30
|
Liu W, Li Z, Kang Q, Wen L. Efficient photocatalytic degradation of doxycycline by coupling α-Bi 2O 3/g-C 3N 4 composite and H 2O 2 under visible light. ENVIRONMENTAL RESEARCH 2021; 197:110925. [PMID: 33737075 DOI: 10.1016/j.envres.2021.110925] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/02/2021] [Accepted: 02/19/2021] [Indexed: 05/26/2023]
Abstract
Antibiotic pollutants have posed a huge threat to the ecological environment and human health. In this work, α-Bi2O3/g-C3N4 composite was prepared and coupled with H2O2 for the rapid and efficient degradation of doxycycline (DOX) in water under visible light irradiation. The composite exhibited enhanced photocatalytic activity and 80.5% of DOX could be degraded in 120 min. The addition of H2O2 significantly improved the degradation efficiency of DOX under visible light, resulting in 79.0% of it degraded within 30 min, and the degradation rate constant of DOX was 3.6 times than that without H2O2. On the one hand, the Z-scheme heterojunction of α-Bi2O3/g-C3N4 promoted the separation rate of photogenerated electron-hole pairs, thereby enhancing the photocatalytic activity of the composite. On the other hand, the improvement of photocatalytic efficiency also benefited from the extra hydroxyl radicals generated by the reaction of photogenerated electrons with H2O2 in the photocatalytic system. Free radicals trapping experiments and electron spin resonance tests proved that played prominent role in the degradation process. After adding H2O2, OH also became important active species. Cyclic degradation experiments demonstrated the recyclability of the composite photocatalyst in DOX elimination applications. This work provides an efficient, clean, and recyclable purification strategy for removing antibiotic contaminants from water.
Collapse
|
31
|
Scimone A, Redfern J, Patiphatpanya P, Thongtem T, Ratova M, Kelly P, Verran J. Development of a rapid method for assessing the efficacy of antibacterial photocatalytic coatings. Talanta 2021; 225:122009. [PMID: 33592748 DOI: 10.1016/j.talanta.2020.122009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 12/08/2020] [Accepted: 12/12/2020] [Indexed: 11/28/2022]
Abstract
Visible-light activated photocatalytic coatings may represent an attractive antimicrobial solution in domains such as food, beverage, pharmaceutical, biomedical and wastewater remediation. However, testing methods to determine the antibacterial effects of photocatalytic coatings are limited and require specialist expertise. This paper describes the development of a method that enables rapid screening of coatings for photocatalytic-antibacterial activity. Relying on the ability of viable microorganisms to reduce the dye resazurin from a blue to a pink colour, the method relates the time taken to detect this colour change with number of viable microorganisms. The antibacterial activity of two photocatalytic materials (bismuth oxide and titanium dioxide) were screened against two pathogenic organisms (Escherichia coli and Klebsiella pneumoniae) that represent potential target microorganisms using traditional testing and enumeration techniques (BS ISO 27447:2009) and the novel rapid method. Bismuth oxide showed excellent antibacterial activity under ambient visible light against E. coli, but was less effective against K. pneumoniae. The rapid method showed excellent agreement with existing tests in terms of number of viable cells recovered. Due to advantages such as low cost, high throughput, and less reliance on microbiological expertise, this method is recommended for researchers seeking an inexpensive first-stage screen for putative photocatalytic-antibacterial coatings.
Collapse
|
32
|
Ghanbari M, Salavati-Niasari M. Copper iodide decorated graphitic carbon nitride sheets with enhanced visible-light response for photocatalytic organic pollutant removal and antibacterial activities. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 208:111712. [PMID: 33396043 DOI: 10.1016/j.ecoenv.2020.111712] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 11/18/2020] [Accepted: 11/20/2020] [Indexed: 06/12/2023]
Abstract
The photocatalytic process is an environmentally-friendly procedure that has been well known in the destruction of organic pollutants in water. The multiple semiconductor heterojunctions are broadly applied to enhance the photocatalytic performances in comparison to the single semiconductor. Polymeric semiconductors have received much attention as inspiring candidates owing to their adjustable optical absorption features and simply adaptable electronic structure. The shortcomings of the current photocatalytic system, which restricts their technical applications incorporate fast charge recombination, low-utilization of visible radiation, and low immigration capability of the photo-induced electron-hole. This paper indicates the novel fabrication of new CuI/g-C3N4 nanocomposite by hydrothermal and ultrasound-assisted co-precipitation methods. The structure, shape, and purity of the products were affected by different weight percentages and fabrication processes. Electron microscope unveils that CuI nanoparticles are distributed on g-C3N4. The bandgap of pure carbon nitride is estimated at 2.70 eV, and the bandgap of the nanocomposite has increased to 2.8 eV via expanding the amount of CuI. The CuI/C3N4 nanocomposite has a great potential to degrade cationic and anionic dyes in high value because of its appropriate bandgap. It can be a great catalyst for water purification. The photocatalytic efficiency is affected by multiple factors such as types of dyes, fabrication methods, the light sources, mass ratios, and scavengers. The fabricated CuI/C3N4 nanocomposite exposes higher photocatalytic performance than the pure C3N4 and CuI. The photocatalytic efficiency of nanocomposite is enhanced by enhancing the amount of CuI. Besides, the fabricated CuI/C3N4 revealed remarkable reusability without the obvious loss of photocatalytic activity. The antibacterial activity of the specimens reveals that the highest antimicrobial activities are revealed against P. aeruginosa and E. coli. These results prove that the nanocomposite possesses high potential for killing bacteria, and it can be nominated as a suitable agent against bacteria.
Collapse
|
33
|
Benabbas K, Zabat N, Hocini I. Facile synthesis of Fe 3O 4/CuO a core-shell heterostructure for the enhancement of photocatalytic activity under visible light irradiation. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:4329-4341. [PMID: 32944857 DOI: 10.1007/s11356-020-10749-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 09/06/2020] [Indexed: 06/11/2023]
Abstract
A magnetically separable Fe3O4/CuO core-shell heterostructure photocatalyst was synthesized by hydrothermal method. The obtained photocatalyst was characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and UV-visible diffuse reflectance (UV-DRS). The obtained photocatalyst was used for the degradation of azo dye Direct Red 89 (DR89), under visible light irradiation provided by fluorescent lamp of 100 W in the presence of 7 mL of H2O2 (30%); the results of the photocatalytic activity for Fe3O4/CuO photocatalyst showed that in the presence of 0.75 g dispersed in 250 mL of 40 mg/L of DR89 dye at pH 6 the dye was completely removed after 240 min. Moreover, the photocatalytic activity of the prepared Fe3O4/CuO was enhanced 11 and 9 times compared with the pure Fe3O4 or CuO. The effect of initial dye concentrations on the photocatalytic activity was studied in the range of 20-60 mg/L, and the results showed that the catalyst has a good photocatalytic activity of 89% even at high concentration (60 mg/L). Furthermore, the catalyst maintained its activity after 5 cycles, and its paramagnetic property facilitates its recovery. The excellent photodegradation activity of Fe3O4/CuO was attributed to the low band gap of the catalyst equal to 1.54 eV and the enhancement of light absorption in visible range of 330-780 nm, but also to a better charge carriers separation, due to the presence of Fe3O4 that reduces electron/hole recombination.
Collapse
|
34
|
Orooji Y, Ghanbari M, Amiri O, Salavati-Niasari M. Facile fabrication of silver iodide/graphitic carbon nitride nanocomposites by notable photo-catalytic performance through sunlight and antimicrobial activity. JOURNAL OF HAZARDOUS MATERIALS 2020; 389:122079. [PMID: 32062394 DOI: 10.1016/j.jhazmat.2020.122079] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/08/2020] [Accepted: 01/11/2020] [Indexed: 05/24/2023]
Abstract
Silver iodide/graphitic carbon nitride nanocomposites have been successfully fabricated through sonication-assisted deposition-precipitation route at room temperature and hydrothermal method. Varied mass ratios and preparation processes can modify the structure, purity, shape, and scale of specimens. The purity of the product was confirmed by Energy Dispersive X-Ray Spectroscopy (EDS) and X-ray crystallography. The morphology and size of specimens could be observed with transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). The bandgap was evaluated around 2.82 eV for pure g-C3N4. The bandgap has reduced to 2.70 eV by increasing the quantity of silver iodide in the nanocomposites. The photocatalytic activity of AgI/C3N4 has been studied over the destruction of rhodamine B (RhB) and methyl orange (MO) through visible radiation due to their suitable bandgap. The as-prepared AgI/C3N4 nanocomposites photocatalyst revealed better photocatalytic behavior than the genuine AgI and C3N4 which ascribed to synergic impacts at the interconnection of C3N4 and AgI. Furthermore, these nanocomposites have great potential for being a great antibacterial agent.
Collapse
|
35
|
Wu M, He X, Jing B, Wang T, Wang C, Qin Y, Ao Z, Wang S, An T. Novel carbon and defects co-modified g-C 3N 4 for highly efficient photocatalytic degradation of bisphenol A under visible light. JOURNAL OF HAZARDOUS MATERIALS 2020; 384:121323. [PMID: 31586913 DOI: 10.1016/j.jhazmat.2019.121323] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 09/14/2019] [Accepted: 09/25/2019] [Indexed: 06/10/2023]
Abstract
Graphite carbon nitride (g-C3N4, CN) is considered as a promising semiconductor for environmental catalysis. However, pure CN can not meet the requirements for actual applications due to its high recombination rate of photogenerated electron-hole pairs and a relatively large band gap preventing full utilization of solar energy. In this work, we report synthesis of a novel carbon and defects co-modified g-C3N4 (CxCN) by calcination of melamine activated by oxalic. This new catalyst CxCN has porous structure with much higher surface areas compared with pristine CN. UV-vis analysis and DFT calculations show that CxCN has a lower bandgap for enhancing visible light adsorption compared with CN. Photoluminescence (PL) and photoelectrochemical analyses show that CxCN has a low recombination rate of photogenerated electron-hole pairs, which improves the utilization of solar energy. As a result, CxCN samples show high efficiency for the degradation of bisphenol A (BPA) under visible light irradiation, where the best catalyst of CxCN (C1.0CN) samples shows about 22 times higher photocatalytic degradation rate than that of CN. Moreover, C1.0CN shows high mineralization rate and can degrade BPA into CO2 and H2O by the generated active species, like superoxide radicals (O2-) and holes (h+).
Collapse
|
36
|
Zhang Z, Yu J, Ma L, Sun Y, Wang P, Wang T, Peng S. Preparation of the plasmonic Ag/AgBr/ZnO film substrate for reusable SERS detection: Implication to the Z-scheme photocatalytic mechanism. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020; 224:117381. [PMID: 31412311 DOI: 10.1016/j.saa.2019.117381] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 06/25/2019] [Accepted: 07/12/2019] [Indexed: 06/10/2023]
Abstract
In this work, a novel Ag/AgBr/ZnO SERS substrate was prepared by calcinating spin-coated zinc acetate on glass slides in the presence of ethanolamine (EA), followed by the process of impregnating-precipitation-photoreduction treatment. The SERS performances of Ag/AgBr/ZnO substrates were evaluated using aqueous crystal violet (CV) and Rhodamine 6G (R6G) as target analytes. The effects of initial immersion precursor concentration and irradiation time on the SERS performance were systematically studied. The as-prepared SERS substrate exhibited good chemical detection sensitivity, reproducibility and reusability. The optimal Ag/AgBr/ZnO (10 mM-30 min) substrates were capable of detecting 10-12 M CV and 10-11 M R6G aqueous solutions. The quantitative detection by the SERS substrate was investigated by constructing a linear corresponding calibration plot. The Ag/AgBr/ZnO SERS substrate was regenerated by a simple visible light driven photocatalytic process. A plausible Z-scheme visible light photocatalytic mechanism seems to account for the Ag-ZnO-AgBr system. This SERS substrate can be separated from the reaction easily, and the results indicated that the film was reusable for eight times without significantly losing the SERS efficiency, each time accompanied by a simple photo-driven regeneration. This study reveals that the Ag/AgBr/ZnO film on glass is practically applicable as an ultra-highly sensitive SERS substrate that can be readily regenerated.
Collapse
|
37
|
Wang L, Bian Z. Photocatalytic degradation of paracetamol on Pd-BiVO 4 under visible light irradiation. CHEMOSPHERE 2020; 239:124815. [PMID: 31526994 DOI: 10.1016/j.chemosphere.2019.124815] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 09/02/2019] [Accepted: 09/07/2019] [Indexed: 05/09/2023]
Abstract
In this study, Pd-BiVO4 bearing highly dispersed Pd nanoparticles was prepared from pure BiVO4 using an impregnation method. The pure BiVO4 and Pd-BiVO4 catalysts were characterized by X-ray diffraction, scanning electron microscopy, UV-visible diffuse reflection, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results showed that the prepared catalysts had a monoclinic scheelite structure and exhibited a flake-like morphology. Pd-BiVO4 showed a distinct response in the visible light region, with an extended absorption edge at 550 nm. According to the Scherrer formula, the nanocrystal particle sizes of the BiVO4 and Pd-BiVO4 catalysts were 35 and 28 nm, respectively. Highly dispersed Pd nanoparticles with sizes of 2.5 ± 0.5 nm were observed on the BiVO4 surface. Two Pd valence states, Pd(II) and Pd(0), were identified in a 2:1 ratio. Pd-BiVO4 exhibited excellent activity for paracetamol (PCT) degradation, with 100% removal achieved in 1 h under visible light irradiation. During degradation, the mineralization ratio reached up to 40% total organic carbon removal. Two highly active species, namely, hydroxyl and superoxide radicals, were determined by electron spin resonance (ESR). Furthermore, the potential degradation of PCT in this system was proposed based on intermediate information obtained using HPLC-MS and Gauss analysis. The high dispersion and small size of Pd nanoparticles might favor the removal of emerging contaminants using the Pd-BiVO4 photocatalytic system.
Collapse
|
38
|
Hu Z, Cai X, Wang Z, Li S, Wang Z, Xie X. Construction of carbon-doped supramolecule-based g-C 3N 4/TiO 2 composites for removal of diclofenac and carbamazepine: A comparative study of operating parameters, mechanisms, degradation pathways. JOURNAL OF HAZARDOUS MATERIALS 2019; 380:120812. [PMID: 31326838 DOI: 10.1016/j.jhazmat.2019.120812] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 06/11/2019] [Accepted: 06/21/2019] [Indexed: 06/10/2023]
Abstract
An eco-friendly 2D heterojunction photocatalyst composites (BCCNT) consisting of carbon-doped supramolecule-based g-C3N4 (BCCN) layers and TiO2 nanoparticles has been fabricated via an in-situ method. Based on the SEM and XPS results affirmed that the coaction of doped carbon and supramolecule precursors lead to the different morphology of pure g-C3N4, C-doped g-C3N4 have improved the photodegradation diclofenac (DCF) and carbamazepine (CBZ). And the degradation efficiencies of DCF and CBZ could reach 98.92% and 99.77%, which were separately corresponded to 30 min (min) and 6 h (h) of LED lamp illumination. Additionally, the effects of catalysis dosage, solution pH, natural organic matter (NOM), inorganic anions (Cl-, SO42-, NO3-) and different water matrices were deeply investigated. The scavenger experiments demonstrated that •O2-, h+ were main active species under visible irradiation. Furthermore, the photodegradation pathways of DCF and CBZ were detected by high-resolution mass spectrometry (HRMS) instruments and three-dimensional excitation-emission matrix fluorescence spectra (3D EEMs). Eventually, the possible photocatalytic mechanisms of BCCNT were proposed.
Collapse
|
39
|
Su R, Ge S, Li H, Su Y, Li Q, Zhou W, Gao B, Yue Q. Synchronous synthesis of Cu 2O/Cu/rGO@carbon nanomaterials photocatalysts via the sodium alginate hydrogel template method for visible light photocatalytic degradation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 693:133657. [PMID: 31635004 DOI: 10.1016/j.scitotenv.2019.133657] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 07/27/2019] [Accepted: 07/27/2019] [Indexed: 06/10/2023]
Abstract
A series of Cu2O/Cu/rGO@carbon nanomaterial (Cu2O/Cu/rGO@CN) heterogeneous photocatalysts were successfully synthesized synchronously via a novel sodium alginate hydrogel method. Cu2O nanoparticles (~50nm) were synthesized by calcination under the protection of a nitrogen atmosphere. Cu nanoparticles (~6nm) inevitably appeared on the surface of Cu2O, thereby forming a Cu2O/Cu heterostructure which is known as a Schottky junction. Graphene oxide (GO) nanosheets were synchronously reduced in situ by sodium alginate during the synthesis process and eventually acted as a 3-D structure with the assistance of the hydrogel skeleton. Because of the 3-D rGO modification, both the adsorption capacity and the photocatalytic activity of Cu2O/Cu/rGO@CN were significantly improved. The rate of p-nitrochlorobenzene (p-NCB) degradation catalyzed by Cu2O/Cu/rGO@CN was ~1.97×10-2min-1, which was much higher than that of the degradation catalyzed by Cu2O/Cu@CN (~0.239×10-2min-1). This result could be attributed to the two-stage Cu2O/Cu/rGO heterostructure, which facilitated efficient electron-hole separation. This method has the advantages of nontoxic raw materials, facile synthesis and reduced auxiliary usage, providing a new technique for designing heterogeneous photocatalysts.
Collapse
|
40
|
Zhang L, Liu F, Xiao X, Zuo X, Nan J. Microwave synthesis of iodine-doped bismuth oxychloride microspheres for the visible light photocatalytic removal of toxic hydroxyl-contained intermediates of parabens: catalyst synthesis, characterization, and mechanism insight. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:28871-28883. [PMID: 31385253 DOI: 10.1007/s11356-019-06074-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Accepted: 07/25/2019] [Indexed: 06/10/2023]
Abstract
The iodine-doped bismuth oxychloride (I-doped BiOCl) microspheres are synthesized as the visible light photocatalysts for the photocatalytic removal of three toxic hydroxyl-contained intermediates of parabens. With the aid of the unique heating mode of microwave method, the I-doped BiOCl photocatalysts with tunable iodine contents and dispersed energy bands, instead of a mixture of BiOI and BiOCl or solid solution, are synthesized under the controllable conditions. Due to the stretched architectures, high specific surface area, and effective separation of photogenerated carriers, they exhibit high activity to the photocatalytic degradation of methyl 2,4-dihydroxybenzoate (MDB), methyl 3,4-dihydroxybenzoate (MDHB), and ethyl 2,4-dihydroxybenzoate (EDB). As a typical result, it is indicated that though MDB as the most difficult intermediate of parabens to be degraded, a 91.2% removal ratio can still be achieved over the I-doped BiOCl with an energy band of 2.79 eV within 60 min. In addition, it is also confirmed that these photocatalysts remain stable throughout the photocatalytic reaction and can be reused, and more importantly, the photogenerated h+ and •O2- are the key reactive species, while •OH plays a negligible role in the photocatalytic reaction. Resorcinol was identified as the main photodegraded intermediate. These results demonstrate that this photocatalytic system not only exhibit a high efficiency but also avoid the consequent secondary pollutions due to the no formation of complex hydroxyl derivatives.
Collapse
|
41
|
Yi C, Liao Q, Deng W, Huang Y, Mao J, Zhang B, Wu G. The preparation of amorphous TiO 2 doped with cationic S and its application to the degradation of DCFs under visible light irradiation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 684:527-536. [PMID: 31154225 DOI: 10.1016/j.scitotenv.2019.05.338] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 05/22/2019] [Accepted: 05/22/2019] [Indexed: 06/09/2023]
Abstract
An amorphous S-doping TiO2 catalyst [S-TiO2 (300)] with visible light catalytic activity was successfully prepared via a sol-gel method with low-temperature calcination (300 °C) using thiourea as the sulfur source. The S-TiO2 (300) catalyst showed great performance in degrading the recalcitrant pharmaceutical, diclofenac (DCF). 93% of the target pollutant DCF degraded in 4 h under visible light irradiation. Both the amorphous form of the catalyst and cationic S-doping (with a coordinated structure) contributed to narrowing the band gap. As a result, the photocatalytic activity of S-TiO2 (300) was significantly enhanced under visible light irradiation. In addition, oxidative species such as photogenic cavitation (h+), OH and O2- were proved to participate in the photodegradation process, attacking COOH group and NH bond, degraded DCF into low molecule organic gradually.
Collapse
|
42
|
Chen CR, Zeng HY, Yi MY, Xiao GF, Zhu RL, Cao XJ, Shen SG, Peng JW. Fabrication of Ag 2O/Ag decorated ZnAl-layered double hydroxide with enhanced visible light photocatalytic activity for tetracycline degradation. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 172:423-431. [PMID: 30735974 DOI: 10.1016/j.ecoenv.2019.01.080] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 01/17/2019] [Accepted: 01/19/2019] [Indexed: 06/09/2023]
Abstract
The photocatalytic performance of layered double hydroxides (LDH) is usually confined to the slow interface mobility and high recombination rate of photogenerated electron-hole pairs in material. To overcome the low photocatalytic efficiency, novel Ag2O/Ag decorated LDH (LDH-Ag2O/Ag) was successfully synthesized by depositing Ag2O on the surface of LDH and then converted to Ag° nanoparticles in the right position after heat treatment. The as-synthesized LDH-Ag2O/Ag composites were characterized by Powder X-ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectra (UV-vis DRS), photoluminescence spectra (PL) and transient photocurrent (TPC) analysis. Compared with virgin LDH, the photocatalytic activities of LDH-Ag2O/Ag composites were enhanced significantly. The optimum photocatalytic efficiency of LDH-Ag10 (0.0184 min-1) was nearly 46 times higher than that of virgin LDH (0.0004 min-1). The result of active species trapping experiments indicated that •OH, h+, and •O2- have an effect on the TC degradation, where •OH played the predominant role during the photocatalytic process. The possible photocatalytic mechanisms involving the charge transfer pathway and reactive species generation during the process of TC degradation were also discussed. The improved photocatalytic activity of LDH-Ag2O/Ag could be attributed to the synergetic effect between LDH and Ag2O/Ag that extended visible light range and reduced photogenerated charge carriers recombination.
Collapse
|
43
|
Hong S, Ratpukdi T, Sungthong B, Sivaguru J, Khan E. A sustainable solution for removal of glutaraldehyde in saline water with visible light photocatalysis. CHEMOSPHERE 2019; 220:1083-1090. [PMID: 33395795 DOI: 10.1016/j.chemosphere.2018.12.216] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 12/25/2018] [Accepted: 12/31/2018] [Indexed: 06/12/2023]
Abstract
Glutaraldehyde (GA) is the most common biocide used in unconventional oil and gas production. Photocatalytic degradation of GA in brine simulating oil and gas produced water using Ag/AgCl/BiOCl composite as a photocatalyst with visible light was investigated. Removal of GA at 0.1 mM in 200 g/L NaCl solution at pH 7 was 90% after 75 min irradiation using 5 g/L of the photocatalyst. The GA removal followed pseudo-first order reaction with a rate constant of 0.0303 min-1. At pH 5 or at 300 g/L NaCl, the photocatalytic removal of GA was almost completely inhibited. Similar inhibitions were observed when adding dissolved organic carbon (from humic acid) at 10 and 200 mg/L, or Br- at 120 mg/L to the system. The removal rate of GA markedly increased with increasing pH (5-9), photocatalyst loading (2-8 g/L) and under 350 nm UV (compared to visible light). On the contrary, the removal rate of GA markedly decreased with increasing NaCl and initial GA concentrations (0-300 g/L for NaCl and 0.1-0.4 mM for GA). A quenching experiment was also conducted; electron holes (h+) and superoxide () were found as the main reactive species responsible for the removal of GA while OH had a very limited effect.
Collapse
|
44
|
Yu L, Wang L, Sun X, Ye D. Enhanced photocatalytic activity of rGO/TiO 2 for the decomposition of formaldehyde under visible light irradiation. J Environ Sci (China) 2018; 73:138-146. [PMID: 30290862 DOI: 10.1016/j.jes.2018.01.022] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 01/17/2018] [Accepted: 01/22/2018] [Indexed: 06/08/2023]
Abstract
Due to the low concentration of indoor air contaminants, photocatalytic technology shows low efficiency for indoor air purification. The application of TiO2 for photocatalytic removal of formaldehyde is limited, because TiO2 can only absorb ultraviolet (UV) light. Immobilization of TiO2 nanoparticles on the surface of graphene can improve the visible light photocatalytic activity and the adsorption capacity. In this study, rGO (reduced graphene oxide)/TiO2 was synthesized through a hydrothermal method using titanium tetrabutoxide and graphene oxide as precursors, and was used for the degradation of low concentration formaldehyde in indoor air under visible light illumination. Characterization of the crystalline structure and morphology of rGO/TiO2 revealed that most GO was reduced to rGO during the hydrothermal treatment, and anatase TiO2 nanoparticles (with particle size of 15-30nm) were dispersed well on the surface of the rGO sheets. rGO/TiO2 exhibited excellent photocatalytic activity for degradation of formaldehyde in indoor air and this can be attributed to the role of rGO, which can act as the electron sink and transporter for separating photo-generated electron-hole pairs through interfacial charge transfer. Furthermore, rGO could adsorb formaldehyde molecules from air to produce a high concentration of formaldehyde on the surface of rGO/TiO2. Under visible light irradiation for 240min, the concentration of formaldehyde could be reduced to 58.5ppbV. rGO/TiO2 showed excellent moisture-resistance behavior, and after five cycles, rGO/TiO2 maintained high photocatalytic activity for the removal of formaldehyde (84.6%). This work suggests that the synthesized rGO/TiO2 is a promising photocatalyst for indoor formaldehyde removal.
Collapse
|
45
|
Stucchi M, Elfiad A, Rigamonti M, Khan H, Boffito DC. Water treatment: Mn-TiO 2 synthesized by ultrasound with increased aromatics adsorption. ULTRASONICS SONOCHEMISTRY 2018; 44:272-279. [PMID: 29680612 DOI: 10.1016/j.ultsonch.2018.01.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 01/16/2018] [Accepted: 01/26/2018] [Indexed: 05/20/2023]
Abstract
Pharma-products are mostly single or multiple cyclic compounds. They pollute surface water and are persistent in the aquatic ecosystem. When irradiated by UV light, TiO2 catalysts cleave or degrade organic contaminants in water. Removal of organics by photocatalysis results from a synergistic effect of adsorption and photocatalysis. Synthesis of catalysts by ultrasound (US) produces high surface area and porous solids. Here, we synthesized Mn-doped TiO2 with a US-assisted sol-gel method. Compared to the classical synthesis, US increased the BET surface area from 83 m2 g-1 to 90 m2 g-1 in the Mn-TiO2 sample and from 9.0 m2 g-1 to 53 m2 g-1 in the control TiO2. Accordingly, acetaminophen and amoxicillin adsorption increased from 44% to 52%, and from 34% to 94% for the Mn-TiO2 obtained in absence and presence of US, respectively. When in a mixture, the two drugs strongly compete for adsorption on TiO2.
Collapse
|
46
|
Li Y, Sun Y, Ho W, Zhang Y, Huang H, Cai Q, Dong F. Highly enhanced visible-light photocatalytic NO x purification and conversion pathway on self-structurally modified g-C 3N 4 nanosheets. Sci Bull (Beijing) 2018; 63:609-620. [PMID: 36658881 DOI: 10.1016/j.scib.2018.04.009] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 04/02/2018] [Accepted: 04/10/2018] [Indexed: 01/21/2023]
Abstract
The unmodified graphitic carbon nitride (g-C3N4) suffers from low photocatalytic activity because of the unfavourable structure. In the present work, we reported a simple self-structural modification strategy to optimize the microstructure of g-C3N4 and obtained graphene-like g-C3N4 nanosheets with porous structure. In contrast to traditional thermal pyrolysis preparation of g-C3N4, the present thermal condensation was improved via pyrolysis of thiourea in an alumina crucible without a cover, followed by secondary heat treatment. The popcorn-like formation and layer-by-layer thermal exfoliation of graphene-like porous g-C3N4 was proposed to explain the formation mechanism. The photocatalytic removal performance of both NO and NO2 with the graphene-like porous g-C3N4 for was significantly enhanced by self-structural modification. Trapping experiments and in-situ diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) measurement were conducted to detect the active species during photocatalysis and the conversion pathway of g-C3N4 photocatalysis for NOx purification was revealed. The photocatalytic activity of graphene-like porous g-C3N4 was highly enhanced due to the improved charge separation and increased oxidation capacity of the O2- radicals and holes. This work could not only provide a novel self-structural modification for design of highly efficient photocatalysts, but also offer new insights into the mechanistic understanding of g-C3N4 photocatalysis.
Collapse
|
47
|
Wang H, He W, Dong X, Wang H, Dong F. In situ FT-IR investigation on the reaction mechanism of visible light photocatalytic NO oxidation with defective g-C 3N 4. Sci Bull (Beijing) 2018; 63:117-125. [PMID: 36658923 DOI: 10.1016/j.scib.2017.12.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Revised: 11/10/2017] [Accepted: 12/05/2017] [Indexed: 01/21/2023]
Abstract
The g-C3N4 with different structures was prepared by heat treatment using urea (CN-U) and thiourea (CN-T) as precursors under the same conditions. The microstructure and optical properties of the photocatalyst were analyzed with advanced tools. The results showed that the CN-U has a porous structure, a high specific surface area and a wide band gap in comparison with CN-T. The in situ FT-IR technique was used to monitor the adsorption and reaction process of visible photocatalytic NO oxidation on g-C3N4. The corresponding reaction mechanism was proposed based on the results of reaction intermediate observation and electron paramagnetic resonance (EPR) radical scavenging. It was revealed that (1) the presence of defective sites favored the adsorption of gas molecules and electronically compensated it leading to promoted formation of the final products; (2) the high separation efficiency of photogenerated electron-hole pairs enhanced the production of radicals during the photocatalytic reaction; (3) the hydroxyl radicals (OH) are not selective for the decomposition of pollutants, which are favorable to the complete oxidation of the reaction intermediates. The above three aspects are the main reasons for the CN-U possessing the efficient visible light photocatalytic activity. The present work could provide new insights and methods for understanding the mechanism of photocatalysis.
Collapse
|
48
|
Stucchi M, Bianchi CL, Argirusis C, Pifferi V, Neppolian B, Cerrato G, Boffito DC. Ultrasound assisted synthesis of Ag-decorated TiO 2 active in visible light. ULTRASONICS SONOCHEMISTRY 2018; 40:282-288. [PMID: 28946426 DOI: 10.1016/j.ultsonch.2017.07.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 07/08/2017] [Accepted: 07/08/2017] [Indexed: 05/12/2023]
Abstract
Titanium dioxide is the most popular photocatalyst to degrade organic pollutants in air, as well as in water. The principal drawback preventing its commercial application lies in its limited absorption of the visible light (400-700nm), while it is active under UV irradiation (≤387nm). Supporting noble metals in the form of nanoparticles on TiO2 increases its activity in the visible range. However, both the synthesis of noble metal nanoparticles and their deposition on TiO2 are multi-step processes that often require organic solvents. Here, we deposit Ag nanoparticles from AgNO3 on the surface of micrometric TiO2 with H2O as a solvent and under ultrasound irradiation at 30Wcm-2. Ultrasound increases the surface amount of Ag on TiO2 with heterogeneous size distribution of Ag nanoparticles, which are bigger and overlaid (1-20nm vs. 0.5-3nm) compared to the sample obtained in traditional conditions (TEM images). While this change in morphology had no effect on acetone photodegradation under UV light, the 5%, 10%, and 20% Ag-TiO2 degraded 17%, 20% and 24% acetone under visible light, respectively. The 10% by weight Ag-TiO2 sample obtained in absence of ultrasound only degraded 14% acetone in 6h, while the bare TiO2 was not active.
Collapse
|
49
|
Al-Saadi MJ, Al-Harthi SH, Kyaw HH, Myint MT, Bora T, Laxman K, Al-Hinai A, Dutta J. Influence of Atomic Hydrogen, Band Bending, and Defects in the Top Few Nanometers of Hydrothermally Prepared Zinc Oxide Nanorods. NANOSCALE RESEARCH LETTERS 2017; 12:22. [PMID: 28063141 PMCID: PMC5218952 DOI: 10.1186/s11671-016-1800-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Accepted: 11/28/2016] [Indexed: 05/22/2023]
Abstract
We report on the surface, sub-surface (top few nanometers) and bulk properties of hydrothermally grown zinc oxide (ZnO) nanorods (NRs) prior to and after hydrogen treatment. Upon treating with atomic hydrogen (H*), upward and downward band bending is observed depending on the availability of molecular H2O within the structure of the NRs. In the absence of H2O, the H* treatment demonstrated a cleaning effect of the nanorods, leading to a 0.51 eV upward band bending. In addition, enhancement in the intensity of room temperature photoluminescence (PL) signals due to the creation of new surface defects could be observed. The defects enhanced the visible light activity of the ZnO NRs which were subsequently used to photocatalytically degrade aqueous phenol under simulated sunlight. On the contrary, in the presence of H2O, H* treatment created an electronic accumulation layer inducing downward band bending of 0.45 eV (~1/7th of the bulk ZnO band gap) along with the weakening of the defect signals as observed from room temperature photoluminescence spectra. The results suggest a plausible way of tailoring the band bending and defects of the ZnO NRs through control of H2O/H* species.
Collapse
|
50
|
Zhang J, Yuan X, Jiang L, Wu Z, Chen X, Wang H, Wang H, Zeng G. Highly efficient photocatalysis toward tetracycline of nitrogen doped carbon quantum dots sensitized bismuth tungstate based on interfacial charge transfer. J Colloid Interface Sci 2017; 511:296-306. [PMID: 29031149 DOI: 10.1016/j.jcis.2017.09.083] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 08/22/2017] [Accepted: 09/21/2017] [Indexed: 12/11/2022]
Abstract
In this study, a novel N-CQDs/Bi2WO6 was synthesized through a facile hydrothermal method. Multiple techniques were applied to investigate the structures, morphologies, optical and electronic properties and photocatalytic performance of as-prepared samples. The results indicated that the hybrid materials were formed with N-CQDs attached on the surface of sphere-like Bi2WO6. The photocatalytic activity of N-CQDs/Bi2WO6 materials was evaluated sufficiently by using tetracycline (TC) as target organic pollutant. N-CQDs/Bi2WO6-5 displayed superior photocatalytic efficiency with nearly 97% removal of TC in 25min and 86.37% mineralization in 90min. The degradation reaction coefficient (kobs) was approximately two times higher than pure Bi2WO6 as a result of the synergistic effects of N-CQDs and Bi2WO6. Increased light harvesting capacity, excellent electron transfer ability and improved molecular oxygen activation ability were obtained in N-CQDs/Bi2WO6 hybrid materials caused by N-CQDs. The present study demonstrated that N-CQDs modification was an effective way to improve photocatalytic efficiency, which can be extended to a general strategy for other semiconductors. The study indicated that novel N-CQDs/Bi2WO6 has a great potential for rapid and efficient treatment of organic pollutants in water.
Collapse
|