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Oluwole AO, Olatunji OS. Enhanced photocatalytic degradation of naproxen in aqueous matrices using reduced graphene oxide (rGO) decorated binary BSO/g-C3N4 heterojunction nanocomposites. CHEMICAL ENGINEERING JOURNAL ADVANCES 2022. [DOI: 10.1016/j.ceja.2022.100417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Koo PL, Choong ZY, Gasim MF, Khoerunnisa F, Jaafar NF, Saputra E, Oh WD. Promotional effect of Ca doping on Bi 2Fe 4O 9 as peroxymonosulfate activator for gatifloxacin removal. CHEMOSPHERE 2022; 307:135619. [PMID: 35835247 DOI: 10.1016/j.chemosphere.2022.135619] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 06/21/2022] [Accepted: 07/03/2022] [Indexed: 06/15/2023]
Abstract
A series of Ca-doped bismuth ferrite was prepared at various %w/w of Ca via a facile hydrothermal method to obtain Bi2XCa2(1-X)Fe4O9 (denoted as BFOCa-X, where X = 1, 0.95, 0.90, 0.80, 0.50). The BFOCa-X catalysts were characterized, and the results showed that they consist of pure phase BFO with nanosheet-like morphology. The as-prepared BFOCa-X catalysts were used as peroxymonosulfate (PMS) activator for gatifloxacin (GAT) removal. It was found that the catalytic activity decreased in the following order: BFOCa-0.8 (90.2% GAT removal efficiency in 45 min, kapp = 0.084 min-1)>BFOCa-0.95 > BFOCa-0.9 > BFOCa-0.5 > BFO indicating that BFOCa-0.8 has the optimized active sites for catalysis. The Ca dopant contributed to the increased oxygen vacancies and surface hydroxyl groups, promoting the catalytic PMS activation process. The kapp value increased gradually with increasing catalyst loading and PMS dosage while pH 9 presented the highest GAT removal rate. The GAT degradation rate was inhibited by PO43-, humic acid and NH4+ but promoted in the presence of Cl-, NO3- and HCO3-. It was also found that the GAT can undergo several degradation pathways in the catalytic PMS system, which eventually mineralized into innocuous compounds. The dominant reactive oxygen species (ROS) were identified using chemical scavengers, revealing that SO4•-, 1O2 and •OH contributed significantly to GAT degradation. Based on the XPS study, PMS was activated by the Fe2+/Fe3+ redox cycling and oxygen vacancies to produce SO4•-/•OH and 1O2, respectively. Overall, the BFOCa-0.8 also showed excellent reusability up to at least 4 cycles with low Bi and Fe leaching (<7 and 62 μg L-1, respectively), indicating that it has promising potential for application as PMS activator for antibiotics removal.
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Affiliation(s)
- Pooi-Ling Koo
- School of Chemical Sciences, Universiti Sains Malaysia, 11800, Penang, Malaysia
| | - Zheng-Yi Choong
- School of Chemical Sciences, Universiti Sains Malaysia, 11800, Penang, Malaysia
| | | | - Fitri Khoerunnisa
- Department of Chemistry, Indonesia University of Education, Setiabudhi 229, Bandung, 40154, Indonesia
| | - Nur Farhana Jaafar
- School of Chemical Sciences, Universiti Sains Malaysia, 11800, Penang, Malaysia
| | - Edy Saputra
- Department of Chemical Engineering, Universitas Riau, Pekanbaru, 28293, Indonesia.
| | - Wen-Da Oh
- School of Chemical Sciences, Universiti Sains Malaysia, 11800, Penang, Malaysia.
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Lin J, Tian W, Zhang H, Duan X, Sun H, Wang H, Fang Y, Huang Y, Wang S. Carbon nitride-based Z-scheme heterojunctions for solar-driven advanced oxidation processes. JOURNAL OF HAZARDOUS MATERIALS 2022; 434:128866. [PMID: 35413519 DOI: 10.1016/j.jhazmat.2022.128866] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/25/2022] [Accepted: 04/02/2022] [Indexed: 06/14/2023]
Abstract
Solar-driven advanced oxidation processes (AOPs) via direct photodegradation or indirect photocatalytic activation of typical oxidants, such as hydrogen peroxide (H2O2), peroxymonosulfate (PMS), and peroxydisulfate (PDS), have been deemed to be an efficient technology for wastewater remediation. Artificial Z-scheme structured materials represent a promising class of photocatalysts due to their spatially separated charge carriers and strong redox abilities. Herein, we summarize the development of metal-free graphitic carbon nitride (g-C3N4, CN)-based direct and indirect Z-scheme photocatalysts for solar-driven AOPs in removing organic pollutants from water. In the work, the classification of AOPs, definition and validation of Z-schemes are summarized firstly. The innovative engineering strategies (e.g., morphology and dimensionality control, element doping, defect engineering, cocatalyst loading, and tandem Z-scheme construction) over CN-based direct Z-scheme structure are then examined. Rational design of indirect CN-based Z-scheme systems using different charge mediators, such as solid conductive materials and soluble ion pairs, is further discussed. Through examining the relationship between the Z-scheme structure and activity (charge transfer and separation, light absorption, and reaction kinetics), we aim to provide more insights into the construction strategies and structure modification on CN-based Z-schemes towards improving their catalytic performances in AOPs. Lastly, limitations, challenges, and perspectives on future development in this emerging field are proposed.
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Affiliation(s)
- Jingkai Lin
- School of Chemical Engineering and Advanced Materials, The University of Adelaide, North Terrace, Adelaide, SA 5005, Australia
| | - Wenjie Tian
- School of Chemical Engineering and Advanced Materials, The University of Adelaide, North Terrace, Adelaide, SA 5005, Australia
| | - Huayang Zhang
- School of Chemical Engineering and Advanced Materials, The University of Adelaide, North Terrace, Adelaide, SA 5005, Australia.
| | - Xiaoguang Duan
- School of Chemical Engineering and Advanced Materials, The University of Adelaide, North Terrace, Adelaide, SA 5005, Australia
| | - Hongqi Sun
- School of Science, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA 6027, Australia
| | - Hao Wang
- Center for Future Materials, University of Southern Queensland, Toowoomba 4350, Australia
| | - Yanfen Fang
- College of Biological and Pharmaceutical Sciences, Three Gorges University, Hubei 443002, China
| | - Yingping Huang
- College of Biological and Pharmaceutical Sciences, Three Gorges University, Hubei 443002, China
| | - Shaobin Wang
- School of Chemical Engineering and Advanced Materials, The University of Adelaide, North Terrace, Adelaide, SA 5005, Australia.
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Keerthana SP, Yuvakkumar R, Senthil Kumar P, Ravi G, Hong SI, Velauthapillai D. Investigation of pure and g-C 3N 4 loaded CdWO 4 photocatalytic activity on reducing toxic pollutants. CHEMOSPHERE 2022; 291:133090. [PMID: 34856234 DOI: 10.1016/j.chemosphere.2021.133090] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 10/22/2021] [Accepted: 11/25/2021] [Indexed: 05/07/2023]
Abstract
A facile synthesis of pristine and g-C3N4 loaded CdWO4 (Cadmium Tungstate) were reported and analyzed the effect of pollutants removal in wastewater. The samples were characterized and the morphology of the pristine sample showed the nanostructures with high cluster of layer formed. While adding PEG (Polyethylene glycol), the surface has exhibited less agglomeration and in g-C3N4 added sample the agglomeration was intensely reduced and nanostructures have been clearly found. Photocatalytic performance on cationic dye was investigated under visible light. The efficiency calculated for g-C3N4- CdWO4 sample was 85% for MB. The C/C0 plot gives better degradation. The kinetic study revealed pseudo first order reaction. The g-C3N4-CdWO4 sample exhibited higher "k" value which proved best efficiency on removing the pollutant. g-C3N4-CdWO4 sample will make better reduction on toxic pollutants and be a good candidate in futuristic applications. By carbon based derivates inclusion with photo active materials, the morphology and surface area was greatly improved and it enhances activity of host material and it will be the promising material for industrial applications.
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Affiliation(s)
- S P Keerthana
- Department of Physics, Alagappa University, Karaikudi, 630 003, Tamil Nadu, India
| | - R Yuvakkumar
- Department of Physics, Alagappa University, Karaikudi, 630 003, Tamil Nadu, India.
| | - P Senthil Kumar
- Department of Chemical Engineering, Sri Sivasubramaniya Nadar College of Engineering, Chennai, 603110, India; Centre of Excellence in Water Research (CEWAR), Sri Sivasubramaniya Nadar College of Engineering, Chennai, 603110, India.
| | - G Ravi
- Department of Physics, Alagappa University, Karaikudi, 630 003, Tamil Nadu, India
| | - S I Hong
- Department of Materials Science and Engineering, Chungnam National University, Daejeon, South Korea
| | - Dhayalan Velauthapillai
- Faculty of Engineering and Science, Western Norway University of Applied Sciences, Bergen, 5063, Norway
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Bahadur A, Iqbal S, Alsaab HO, Awwad NS, Ibrahium HA. Designing a novel visible-light-driven heterostructure Ni-ZnO/S-g-C 3N 4 photocatalyst for coloured pollutant degradation. RSC Adv 2021; 11:36518-36527. [PMID: 35494399 PMCID: PMC9043585 DOI: 10.1039/d0ra09390d] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 11/08/2021] [Indexed: 01/25/2023] Open
Abstract
In this study, photocorrosion of ZnO is inhibited by doping Ni in the ZnO nanostructure and electron-hole recombination was solved by forming a heterostructure with S-g-C3N4. Ni is doped into ZnO NPs from 0 to 10% (w/w). Among the Ni-decorated ZnO NPs, 4% Ni-doped ZnO NPs (4NZO) showed the best performance. So, 4% Ni-ZnO was used to form heterostructure NCs with S-g-C3N4. NZO NPs were formed by the wet co-precipitation route by varying the weight percentage of Ni (0-10% w/w). Methylene blue (MB) was used as a model dye for photocatalytic studies. For the preparation of the 4NZO-x-SCN nanocomposite, 4NZO NPs were formed in situ in the presence of various concentrations of S-g-C3N4 (10-50% (w/w)) by using the coprecipitation route. The electron spin resonance (ESR) and radical scavenger studies showed that O2 - and OH free radicals were the main reactive species that were responsible for MB photodegradation.
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Affiliation(s)
- Ali Bahadur
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University Seoul 08826 South Korea
| | - Shahid Iqbal
- Department of Chemistry, School of Natural Sciences (SNS), National University of Science and Technology (NUST) H-12 Islamabad 46000 Pakistan
| | - Hashem O Alsaab
- Department of Pharmaceutics and Pharmaceutical Technology, Taif University P. O. Box 11099 Taif 21944 Saudi Arabia
| | - Nasser S Awwad
- Research Center for Advanced Materials Science (RCAMS), King Khalid University P. O. Box 9004 Abha 61413 Saudi Arabia
| | - Hala A Ibrahium
- Research Center for Advanced Materials Science (RCAMS), King Khalid University P. O. Box 9004 Abha 61413 Saudi Arabia.,Department of Semi Pilot Plant, Nuclear Materials Authority P. O. Box 530, El Maadi Egypt
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Han Y, Zhou J, Wang L, Xing L, Xue Z, Jiao Y, Pang Y. Redox-active nanostructure electrode of Mn/Ni bimetal organic frameworks anchoring on multi-walled carbon nanotubes for advanced supercapacitor. J Electroanal Chem (Lausanne) 2021. [DOI: 10.1016/j.jelechem.2021.114993] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Xu T, Geng Z, Su Y. A Potential Plasmonic Biosensor Based Asymmetric Metal Ring Cavity with Extremely Narrow Linewidth and High Sensitivity. SENSORS 2021; 21:s21030752. [PMID: 33499375 PMCID: PMC7865613 DOI: 10.3390/s21030752] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/14/2021] [Accepted: 01/20/2021] [Indexed: 01/28/2023]
Abstract
To achieve high sensitivity and multi-mode sensing characteristics based on the plasmon effect, we explored a high-sensitivity refractive index sensor structure with narrow linewidth and high absorption characteristics based on theoretical analysis. The sensor structure is composed of periodic asymmetric ring cavity array, spacer layer and metal thin-film layer. The reflection spectrum of this structure shows six resonance modes in the wavelength range from visible to near-infrared. The sensor performance was optimized based on the change of the sensor structure parameters combining the simulation data, and the results shown that this kind of asymmetric laminated structure sensor has good sensing performance. In theory, it can be combined with microfluidic technology to achieve sensing detection of diverse test samples, multi-mode and multi-component, which has great potential in the field of biosensing.
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Affiliation(s)
- Tianping Xu
- College of Science, Minzu University of China, Beijing 100081, China;
| | - Zhaoxin Geng
- School of Information Engineering, Minzu University of China, Beijing 100081, China
- State Key Laboratory for Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China;
- Correspondence: ; Tel.: +86-10-8230-4531
| | - Yue Su
- State Key Laboratory for Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China;
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Abstract
Graphitic carbon nitride (g-C3N4) was supported on SrAl2O4:Eu,Dy-SiO2 by a colloidal-sol coating method to improve its light absorption property. Transmission electron microscopy (TEM) revealed that the nanoparticles of g-C3N4 were coated on sub-micron phosphor particles and nanoscale surface roughness was imparted by the SiO2-binder. Photoluminescence (PL) spectrum of the g-C3N4 supported on SrAl2O4:Eu,Dy exhibited a broadband emission from 400 to 650 nm. Increasing silica-binder in the g-C3N4/SrAl2O4:Eu,Dy composites suppressed the PL emission peak at 525 nm for SrAl2O4:Eu,Dy. Photocatalytic degradation activity was evaluated with 5 ppm methylene blue (MB) solutions under germicidal ultraviolet (UV) and visible (Vis) solar light illuminations. The UV/Vis photocatalytic efficiency was improved by supporting g-C3N4 on the SrAl2O4:Eu,Dy phosphor and with the addition of SiO2 as a binder. In addition, low silica addition effectively improved the adhesiveness of the g-C3N4 coating on the SrAl2O4:Eu,Dy surface. Recyclability tests of photocatalysis for the SrAl2O4:Eu,Dy-0.01M SiO2/50wt% g-C3N4 composites exhibited a remarkable stability by maintaining the degradation efficiencies above 90% in four cycles. Therefore, the composite of g-C3N4-supported SrAl2O4:Eu,Dy-SiO2 is a prospective photocatalyst activating under UV/Vis light irradiation for the elimination of environmental pollutants.
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Wang Y, Jiang F, Chen J, Sun X, Xian T, Yang H. In Situ Construction of CNT/CuS Hybrids and Their Application in Photodegradation for Removing Organic Dyes. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E178. [PMID: 31968569 PMCID: PMC7022525 DOI: 10.3390/nano10010178] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 01/13/2020] [Accepted: 01/17/2020] [Indexed: 11/26/2022]
Abstract
Herein, a coprecipitation method used to synthesize CuS nanostructures is reported. By varying the reaction time and temperature, the evolution of the CuS morphology between nanoparticles and nanoflakes was investigated. It was found that CuS easily crystallizes into sphere-/ellipsoid-like nanoparticles within a short reaction time (0.5 h) or at a high reaction temperature (120 °C), whereas CuS nanoflakes are readily formed at a low reaction temperature (20 °C) for a long time (12 h). Photodegradation experiments demonstrate that CuS nanoflakes exhibit a higher photodegradation performance than CuS nanoparticles for removing rhodamine B (RhB) from aqueous solution under simulated sunlight irradiation. Carbon nanotubes (CNTs) were further used to modify the photodegradation performance of a CuS photocatalyst. To achieve this aim, CNTs and CuS were integrated to form CNT/CuS hybrid composites via an in situ coprecipitation method. In the in situ constructed CNT/CuS composites, CuS is preferably formed as nanoparticles, but cannot be crystallized into nanoflakes. Compared to bare CuS, the CNT/CuS composites manifest an obviously enhanced photodegradation of RhB; notably, the 3% CNT/CuS composite with CNT content of 3% showed the highest photodegradation performance (η = 89.4% for 120 min reaction, kapp = 0.01782 min-1). To make a comparison, CuS nanoflakes and CNTs were mechanically mixed in absolute alcohol and then dried to obtain the 3% CNT/CuS-MD composite. It was observed that the 3% CNT/CuS-MD composite exhibited a slightly higher photodegradation performance (η = 92.4%, kapp = 0.0208 min-1) than the 3% CNT/CuS composite, which may be attributed to the fact that CuS maintains the morphology of nanoflakes in the 3% CNT/CuS-MD composite. The underlying enhanced photocatalytic mechanism of the CNT/CuS composites was systematically investigated and discussed.
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Affiliation(s)
- Yanping Wang
- School of Science, Lanzhou University of Technology, Lanzhou 730050, China; (Y.W.); (F.J.)
| | - Fuchuan Jiang
- School of Science, Lanzhou University of Technology, Lanzhou 730050, China; (Y.W.); (F.J.)
| | - Jiafu Chen
- Ministry of Education Key Laboratory of Testing Technology for Manufacturing Process, Southwest University of Science and Technology, Mianyang 621010, China;
| | - Xiaofeng Sun
- College of Physics and Electronic Information Engineering, Qinghai Normal University, Xining 810008, China; (X.S.); (T.X.)
| | - Tao Xian
- College of Physics and Electronic Information Engineering, Qinghai Normal University, Xining 810008, China; (X.S.); (T.X.)
| | - Hua Yang
- School of Science, Lanzhou University of Technology, Lanzhou 730050, China; (Y.W.); (F.J.)
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Carbon Quantum Dots (CQDs) Decorated Bi2O3-x Hybrid Photocatalysts with Promising NIR-Light-Driven Photodegradation Activity for AO7. Catalysts 2019. [DOI: 10.3390/catal9121031] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In this work, Bi2O3-x with surface oxygen vacancies was prepared through the NaBH4 reduction of Bi2O3. After that, carbon quantum dots (CQDs) were deposited onto the surface of the Bi2O3-x to obtain a series of the CQDs/Bi2O3-x composites. The HRTEM and XPS characterizations of the CQDs/Bi2O3-x composites suggest that the thickness of surface oxygen vacancies could be adjusted by changing the concentration of NaBH4 solution, and the intimate contact between CQDs and the Bi2O3-x is achieved. Acid orange 7 (AO7) was adopted as the target reactant for investigating the photocatalytic degradation activities of the CQDs/Bi2O3-x composites under simulated sunlight and NIR light irradiation. It is found that the photocatalytic activities of the samples are closely related to the concentration of NaBH4 and content of CQDs. The Bi2O3-x samples exhibit enhanced simulated-sunlight-driven photocatalytic activity compared with Bi2O3. Specifically, the optimal degradation efficiency of AO7 is achieved over the 3R-Bi2O3-x (concentration of NaBH4: 3 mmol/L), which is 1.38 times higher than the degradation AO7 efficiency over Bi2O3. After the decoration of the 3R-Bi2O3-x surface with CQDs, the simulated-sunlight-driven photocatalytic activity of the CQDs/Bi2O3-x composite could be further enhanced. Among the samples, the 15C/3R-Bi2O3-x sample reveals the highest photocatalytic activity, leading to an AO7 degradation percentage of ~97% after 60 min irradiation. Different from Bi2O3 and the 3R-Bi2O3-x, the 15C/3R-Bi2O3-x sample also exhibits near-infrared (NIR)-light-driven photocatalytic degradation activity. In addition, the intrinsic photocatalytic activity of CQDs/Bi2O3-x composite was further confirmed by the degradation of phenol under simulated sunlight and NIR light irradiation. The photocurrent response and electrochemical impedance spectroscopy (EIS) measurements confirm the efficient migration and separation of photogenerated charges in the CQDs/Bi2O3-x samples. The •OH and h+ are proved to be the main reactive species in the simulated sunlight and NIR light photocatalytic processes over the CQDs/Bi2O3-x composites. According to the above experiments, the photocatalytic degradation mechanisms of the CQDs/Bi2O3-x composites under simulated sunlight and NIR light illumination were proposed.
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Ranjith KS, Satilmis B, Huh YS, Han YK, Uyar T. Highly selective surface adsorption-induced efficient photodegradation of cationic dyes on hierarchical ZnO nanorod-decorated hydrolyzed PIM-1 nanofibrous webs. J Colloid Interface Sci 2019; 562:29-41. [PMID: 31830629 DOI: 10.1016/j.jcis.2019.11.096] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 11/22/2019] [Accepted: 11/23/2019] [Indexed: 12/12/2022]
Abstract
Selectivity of catalysts toward harmful cationic pollutants in industrial wastewater remains challenging but is of crucial importance in environmental remediation processes. Here, we present a complex network of a hydrolyzed polymer of intrinsic microporosity (HPIM)-based electrospun nanofibrous web with surface functional decoration of ZnO nanorods (NRs) as a hierarchical platform for selective and rapid degradation of cationic dyes. Over a single species or binary mixtures, cationic dyes were selectively adsorbed by the HPIM surface, which then rapidly degraded under simultaneous photoirradiation through the ZnO NRs. Both HPIM and ZnO exhibited high electronegative surfaces, which induced the selectivity towards the cationic dyes and rapidly degraded the pollutants with the production of reactive oxygen species under photoirradiation. Further, as a free-standing web, the catalytic network could be easily separated and reused without any significant loss of catalytic activity after multiple cycles of use. The hierarchical platform of ZnO/HPIM-based heterostructures could be a promising catalytic template for selective degradation of synthetic dyes in mixed wastewater samples.
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Affiliation(s)
- Kugalur Shanmugam Ranjith
- Institute of Materials Science & Nanotechnology, Bilkent University, Ankara 06800, Turkey; Department of Energy and Material Engineering, Dongguk University, Seoul 04620, Republic of Korea.
| | - Bekir Satilmis
- Institute of Materials Science & Nanotechnology, Bilkent University, Ankara 06800, Turkey; Department of Medical Services and Techniques, Vocational School of Health Services, Kirsehir Ahi Evran University, Kirsehir 40100, Turkey
| | - Yun Suk Huh
- Department of Biological Engineering, Inha University, Incheon 22122, Republic of Korea
| | - Young-Kyu Han
- Department of Energy and Material Engineering, Dongguk University, Seoul 04620, Republic of Korea.
| | - Tamer Uyar
- Institute of Materials Science & Nanotechnology, Bilkent University, Ankara 06800, Turkey; Department of Fiber Science & Apparel Design, Cornell University, Ithaca, NY 14853, United States.
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Wang S, Yang H, Yi Z, Wang X. Enhanced photocatalytic performance by hybridization of Bi 2WO 6 nanoparticles with honeycomb-like porous carbon skeleton. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2019; 248:109341. [PMID: 31382192 DOI: 10.1016/j.jenvman.2019.109341] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 07/18/2019] [Accepted: 07/30/2019] [Indexed: 05/25/2023]
Abstract
In this work, we have assembled Bi2WO6 nanoparticles on the surface of honeycomb-like porous carbon skeleton (PCS) via a hydrothermal route to achieve a new type of PCS@Bi2WO6 hybrid composite photocatalysts. The PCS@Bi2WO6 hybrid structures are determined by SEM, TEM and XPS characterizations. UV-vis DRS investigation suggests an enhanced visible-light absorption of the PCS@Bi2WO6 composites. Transient photocurrent response, EIS and PL spectroscopy characterizations demonstrate that the composites exhibit an efficient separation of photoproduced electron/hole pairs. The photocatalytic performance of the composites were evaluated by using RhB as the model pollutant and simulated sunlight as the light source. It is revealed that the PCS@Bi2WO6 hybrid composites manifest much enhanced photocatalytic performance. The 5 wt%PCS@Bi2WO6 composite manifests the highest photocatalytic activity, which is ca. 2.1 times as large as that of bare Bi2WO6 nanoparticles. This can be mainly ascribed to two factors: (1) The photogenerated electron/hole pairs in Bi2WO6 are efficiently separated due to the electron transfer between Bi2WO6 and PCS; and (2) PCS induces enhanced visible-light absorption and the visible-light-excited electrons in PCS could also take part in the photocatalytic reactions.
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Affiliation(s)
- Siyuan Wang
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou, 730050, China
| | - Hua Yang
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou, 730050, China.
| | - Zao Yi
- Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology, Mianyang, 621010, China
| | - Xiangxian Wang
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou, 730050, China
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Yan Y, Yang H, Yi Z, Xian T, Wang X. Direct Z-scheme CaTiO 3@BiOBr composite photocatalysts with enhanced photodegradation of dyes. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:29020-29031. [PMID: 31388948 DOI: 10.1007/s11356-019-06085-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 07/26/2019] [Indexed: 05/25/2023]
Abstract
To efficiently separate photoexcited electron/hole pairs is one of the key points for achieving excellent photocatalysts with high photocatalytic performances. To achieve this aim, here we have assembled CaTiO3 (CTO) nanoparticles onto BiOBr microplates, thus constructing novel Z-scheme CTO@BiOBr heterojunction composite photocatalysts. Observation by scanning/transmission electron microscopy confirms the good decoration of CTO nanoparticles (15-50 nm) on the surface of BiOBr microplates (diameter 0.7-2.2 μm, thickness 70-110 nm). Simulated sunlight was used as the light source, and rhodamine B (RhB) in aqueous solution was used as the model pollutant to assess the photodegradation activity of the samples. It is demonstrated that the CTO@BiOBr composites with an appropriate CTO content exhibit much enhanced photodegradation performances. In particular, the 10%CTO@BiOBr composite with a CTO mass fraction of 10%, which photocatalyzes 99.9% degradation of RhB at 30 min of photocatalysis, has a photocatalytic activity which is about 1.8 and 23.6 times larger than that of bare BiOBr microplates and CTO nanoparticles, respectively. This can be explained as the result of the Z-scheme electron transfer and efficient separation of photoexcited electron/hole pairs, as evidenced by photoluminescence, photocurrent response, and electrochemical impedance spectroscopy investigations.
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Affiliation(s)
- Yuxiang Yan
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou, 730050, China
| | - Hua Yang
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou, 730050, China.
| | - Zao Yi
- Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology, Mianyang, 621010, China
| | - Tao Xian
- College of Physics and Electronic Information Engineering, Qinghai Normal University, Xining, 810008, China
| | - Xiangxian Wang
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou, 730050, China
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NaBH4-Reduction Induced Evolution of Bi Nanoparticles from BiOCl Nanoplates and Construction of Promising Bi@BiOCl Hybrid Photocatalysts. Catalysts 2019. [DOI: 10.3390/catal9100795] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In this work, we have synthesized BiOCl nanoplates (diameter 140–220 nm, thickness 60–70 nm) via a co-precipitation method, and then created Bi nanoparticles (diameter 35–50 nm) on the surface of BiOCl nanoplates via a NaBH4 reduction method. By varying the NaBH4 concentration and reaction time, the evolution of Bi nanoparticles was systematically investigated. It is demonstrated that with increasing the NaBH4 concentration (at a fixing reaction time of 30 min), BiOCl crystals are gradually reduced into Bi nanoparticles, and pure Bi nanoparticles are formed at 120 mM NaBH4 solution treatment. At low-concentration NaBH4 solutions (e.g., 10 and 30 mM), with increasing the reaction time, BiOCl crystals are partially reduced into Bi nanoparticles, and then the Bi nanoparticles return to form BiOCl crystals. At high-concentration NaBH4 solutions (e.g., 120 mM), BiOCl crystals are reduced to Bi nanoparticles completely with a short reaction time, and further prolong the treatment time leads to the transformation of the Bi nanoparticles into a two-phase mixture of BiOCl and Bi2O3 nanowires. The photodegradation performances of the samples were investigated by choosing rhodamine B (RhB) as the model pollutant and using simulated sunlight as the light source. It is demonstrated that an enhanced photodegradation performance can be achieved for the created Bi@BiOCl hybrid composites with appropriate NaBH4 treatment. The underlying photocatalytic mechanism was systematically investigated and discussed.
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Gebreslassie G, Bharali P, Chandra U, Sergawie A, Boruah PK, Das MR, Alemayehu E. Novel g-C3N4/graphene/NiFe2O4 nanocomposites as magnetically separable visible light driven photocatalysts. J Photochem Photobiol A Chem 2019. [DOI: 10.1016/j.jphotochem.2019.111960] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Construction of a CQDs/Ag 3PO 4/BiPO 4 Heterostructure Photocatalyst with Enhanced Photocatalytic Degradation of Rhodamine B under Simulated Solar Irradiation. MICROMACHINES 2019; 10:mi10090557. [PMID: 31450790 PMCID: PMC6780486 DOI: 10.3390/mi10090557] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 08/13/2019] [Accepted: 08/21/2019] [Indexed: 12/12/2022]
Abstract
A carbon quantum dot (CQDs)/Ag3PO4/BiPO4 heterostructure photocatalyst was constructed by a simple hydrothermal synthesis method. The as-prepared CQDs/Ag3PO4/BiPO4 photocatalyst has been characterized in detail by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible spectroscopy, and photoelectrochemical measurements. It is demonstrated that the CQDs/Ag3PO4/BiPO4 composite is constructed by assembling Ag3PO4 fine particles and CQDs on the surface of rice-like BiPO4 granules. The CQDs/Ag3PO4/BiPO4 heterostructure photocatalyst exhibits a higher photocatalytic activity for the degradation of the rhodamine B dye than that of Ag3PO4, BiPO4, and Ag3PO4/BiPO4. The synergistic effects of light absorption capacity, band edge position, separation, and utilization efficiency of photogenerated carriers play the key role for the enhanced photodegradation of the rhodamine B dye.
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17
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Di L, Xian T, Sun X, Li H, Zhou Y, Ma J, Yang H. Facile Preparation of CNT/Ag 2S Nanocomposites with Improved Visible and NIR Light Photocatalytic Degradation Activity and Their Catalytic Mechanism. MICROMACHINES 2019; 10:mi10080503. [PMID: 31366070 PMCID: PMC6723643 DOI: 10.3390/mi10080503] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 07/20/2019] [Accepted: 07/24/2019] [Indexed: 11/22/2022]
Abstract
In this work, a series of carbon nanotubes (CNT)/Ag2S hybrid nanocomposites were successfully prepared by a facile precipitation method. Transmission electron microscope (TEM) observation indicates that Ag2S nanoparticles with an average particle size of ~25 nm are uniformly anchored on the surface of CNT. The photocatalytic activities of the CNT/Ag2S nanocomposites were investigated toward the degradation of rhodamine B (RhB) under visible and near-infrared (NIR) light irradiation. It is shown that the nanocomposites exhibit obviously enhanced visible and NIR light photocatalytic activities compared with bare Ag2S nanoparticles. Moreover, the recycling photocatalytic experiment demonstrates that the CNT/Ag2S nanocomposites possess excellent photocatalytic stability. The photoelectrochemical and photoluminescence measurements reveal the efficient separation of photogenerated charges in the CNT/Ag2S nanocomposites. This is the dominant reason behind the improvement of the photocatalytic activity. Based on active species trapping experiments, the possible photocatalytic mechanism of CNT/Ag2S nanocomposites for dye degradation under visible and NIR light irradiation was proposed.
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Affiliation(s)
- Lijing Di
- College of Physics and Electronic Information Engineering, Qinghai Normal University, Xining 810008, China
| | - Tao Xian
- College of Physics and Electronic Information Engineering, Qinghai Normal University, Xining 810008, China.
| | - Xiaofeng Sun
- College of Physics and Electronic Information Engineering, Qinghai Normal University, Xining 810008, China
| | - Hongqin Li
- College of Physics and Electronic Information Engineering, Qinghai Normal University, Xining 810008, China
| | - Yongjie Zhou
- College of Physics and Electronic Information Engineering, Qinghai Normal University, Xining 810008, China
| | - Jun Ma
- College of Physics and Electronic Information Engineering, Qinghai Normal University, Xining 810008, China
| | - Hua Yang
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China
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Singh J, Sharma S, Aanchal, Basu S. Synthesis of Fe2O3/TiO2 monoliths for the enhanced degradation of industrial dye and pesticide via photo-Fenton catalysis. J Photochem Photobiol A Chem 2019. [DOI: 10.1016/j.jphotochem.2019.03.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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19
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Enhanced Photocatalytic Performance and Mechanism of Au@CaTiO 3 Composites with Au Nanoparticles Assembled on CaTiO 3 Nanocuboids. MICROMACHINES 2019; 10:mi10040254. [PMID: 30999566 PMCID: PMC6523114 DOI: 10.3390/mi10040254] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 04/05/2019] [Accepted: 04/15/2019] [Indexed: 12/28/2022]
Abstract
Using P25 as the titanium source and based on a hydrothermal route, we have synthesized CaTiO3 nanocuboids (NCs) with the width of 0.3–0.5 μm and length of 0.8–1.1 μm, and systematically investigated their growth process. Au nanoparticles (NPs) of 3–7 nm in size were assembled on the surface of CaTiO3 NCs via a photocatalytic reduction method to achieve excellent Au@CaTiO3 composite photocatalysts. Various techniques were used to characterize the as-prepared samples, including X-ray powder diffraction (XRD), scanning/transmission electron microscopy (SEM/TEM), diffuse reflectance spectroscopy (UV-vis DRS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Rhodamine B (RhB) in aqueous solution was chosen as the model pollutant to assess the photocatalytic performance of the samples separately under simulated-sunlight, ultraviolet (UV) and visible-light irradiation. Under irradiation of all kinds of light sources, the Au@CaTiO3 composites, particularly the 4.3%Au@CaTiO3 composite, exhibit greatly enhanced photocatalytic performance when compared with bare CaTiO3 NCs. The main roles of Au NPs in the enhanced photocatalytic mechanism of the Au@CaTiO3 composites manifest in the following aspects: (1) Au NPs act as excellent electron sinks to capture the photoexcited electrons in CaTiO3, thus leading to an efficient separation of photoexcited electron/hole pairs in CaTiO3; (2) the electromagnetic field caused by localized surface plasmon resonance (LSPR) of Au NPs could facilitate the generation and separation of electron/hole pairs in CaTiO3; and (3) the LSPR-induced electrons in Au NPs could take part in the photocatalytic reactions.
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Di L, Yang H, Xian T, Liu X, Chen X. Photocatalytic and Photo-Fenton Catalytic Degradation Activities of Z-Scheme Ag₂S/BiFeO₃ Heterojunction Composites under Visible-Light Irradiation. NANOMATERIALS (BASEL, SWITZERLAND) 2019; 9:E399. [PMID: 30857308 PMCID: PMC6473958 DOI: 10.3390/nano9030399] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 02/28/2019] [Accepted: 03/05/2019] [Indexed: 01/07/2023]
Abstract
Z-scheme Ag₂S/BiFeO₃ heterojunction composites were successfully prepared through a precipitation method. The morphology and microstructure characterization demonstrate that Ag₂S nanoparticles (30⁻50 nm) are well-decorated on the surfaces of polyhedral BiFeO₃ particles (500⁻800 nm) to form Ag₂S/BiFeO₃ heterojunctions. The photocatalytic and photo-Fenton catalytic activities of the as-derived Ag₂S/BiFeO₃ heterojunction composites were evaluated by the degradation of methyl orange (MO) under visible-light irradiation. The photocatalytic result indicates that the Ag₂S/BiFeO₃ composites exhibit much improved photocatalytic activities when compared with bare Ag₂S and BiFeO₃. The optimum composite sample was observed to be 15% Ag₂S/BiFeO₃ with an Ag₂S mass fraction of 15%. Furthermore, the addition of H₂O₂ can further enhance the dye degradation efficiency, which is due to the synergistic effects of photo- and Fenton catalysis. The results of photoelectrochemical and photoluminescence measurements suggest a greater separation of the photoexcited electron/hole pairs in the Ag₂S/BiFeO₃ composites. According to the active species trapping experiments, the photocatalytic and photo-Fenton catalytic mechanisms of the Ag₂S/BiFeO₃ composites were proposed and discussed.
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Affiliation(s)
- Lijing Di
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China.
- College of Physics and Electronic Information Engineering, Qinghai Normal University, Xining 810008, China.
| | - Hua Yang
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China.
| | - Tao Xian
- College of Physics and Electronic Information Engineering, Qinghai Normal University, Xining 810008, China.
| | - Xueqin Liu
- School of Science, Chongqing University of Technology, Chongqing 4000054, China.
| | - Xiujuan Chen
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China.
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Theoretical Investigation of a Highly Sensitive Refractive-Index Sensor Based on TM₀ Waveguide Mode Resonance Excited in an Asymmetric Metal-Cladding Dielectric Waveguide Structure. SENSORS 2019; 19:s19051187. [PMID: 30857160 PMCID: PMC6427475 DOI: 10.3390/s19051187] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 02/26/2019] [Accepted: 03/04/2019] [Indexed: 02/04/2023]
Abstract
This study proposes a highly sensitive refractive-index (RI) sensor based on a TM₀ waveguide mode resonance excited in an asymmetric metal-cladding dielectric waveguide structure, where the analyte serves as the guiding layer. By scanning the wavelength at fixed angles of incidence, the reflection spectra of the sensor were obtained. The results showed that the resonance wavelength redshifted dramatically with increases in the analyte RI, which indicates that this approach can be used to sense both the resonance wavelength and the analyte RI. Based on this approach, we investigated the sensing properties, including the sensitivity and figure of merit, at fixed incident angles of 60° and 45°, at which the sensitivity of the sensor reached 7724.9 nm/RIU (refractive index units) and 1339 nm/RIU, respectively. Compared with surface plasmon resonance sensors, which are based on a similar structure, the proposed sensor can accept a more flexible range of incident angles and a wider sensing range of analyte RI. This approach thus has tremendous potential for use in numerous sensing domains, such as biochemical and medical analyses.
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22
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Li X, Chen X, Yi Z, Zhou Z, Tang Y, Yi Y. Fabriction of ZnO Nanorods with Strong UV Absorption and Different Hydrophobicity on Foamed Nickel under Different Hydrothermal Conditions. MICROMACHINES 2019; 10:mi10030164. [PMID: 30818788 PMCID: PMC6472276 DOI: 10.3390/mi10030164] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 02/15/2019] [Accepted: 02/24/2019] [Indexed: 11/16/2022]
Abstract
ZnO nanorods have been grown on the surface of foamed nickel by a two-step method. Firstly, a layer of ZnO seed is sputtered on the surface of the foamed nickel by magnetron sputtering, and then the hydrothermal method is used to grow ZnO nanorods at different conditions (solution concentration, reaction time and reaction temperature). The results show that the morphology of ZnO nanorods is closely related to the solution concentration, reaction time, and reaction temperature. The energy band structure formed by the foamed nickel and ZnO seed layers and the growth mechanism of ZnO nanorods are discussed. The samples are characterized by Energy dispersive spectrometer (EDS), X-ray diffraction (XRD), and Raman spectroscopy. The absorption characteristics of samples to light are characterized by ultraviolet-to-visible (UV–VIS) absorption. The hydrophilicity of the samples is characterized by the static contact angle. By analyzing the performance characteristics of the samples at different conditions, we finally obtained the optimal growth parameters. At the optimal parameters, the morphology of the grown nanorods is regular, the ultraviolet band has strong absorption, and the surface of the samples forms a superhydrophobic surface.
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Affiliation(s)
- Xin Li
- Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology, Mianyang 621010, China.
- Sichuan Civil-Military Integration Institute, Mianyang 621010, China.
| | - Xifang Chen
- Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology, Mianyang 621010, China.
- Sichuan Civil-Military Integration Institute, Mianyang 621010, China.
| | - Zao Yi
- Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology, Mianyang 621010, China.
- Sichuan Civil-Military Integration Institute, Mianyang 621010, China.
| | - Zigang Zhou
- Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology, Mianyang 621010, China.
- Sichuan Civil-Military Integration Institute, Mianyang 621010, China.
| | - Yongjian Tang
- Sichuan Civil-Military Integration Institute, Mianyang 621010, China.
| | - Yougen Yi
- College of Physics and Electronics, Central South University, Changsha 410083, China.
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23
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Kamoun O, Mami A, Amara MA, Vidu R, Amlouk M. Nanostructured Fe,Co-Codoped MoO₃ Thin Films. MICROMACHINES 2019; 10:mi10020138. [PMID: 30791584 PMCID: PMC6412870 DOI: 10.3390/mi10020138] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 02/13/2019] [Accepted: 02/15/2019] [Indexed: 11/30/2022]
Abstract
Molybdenum oxide (MoO3) and Fe,Co-codoped MoO3 thin films obtained by spray pyrolysis have been in-depth investigated to understand the effect of Co and Fe codoping on MoO3 thin films. The effect of Fe and Co on the structural, morphological and optical properties of MoO3 thin films have been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray analysis (EDAX), optical and photoluminescence (PL) spectroscopy, and electropyroelectric methods. The XRD patterns demonstrated the formation of orthorhombic α-MoO3 by spray pyrolysis. SEM characterization has shown an increase in roughness of MoO3 thin films by Fe and Co doping. Optical reflectance and transmittance measurements have shown an increase in optical band gap with the increase in Fe and Co contents. Thermal conductivity and thermal diffusivity of Fe,Co-doped MoO3 were 24.10–25.86 Wm−1K−1 and 3.80 × 10−6–5.15 × 10−6 m2s−1, respectively. MoO3 thin films have shown PL emission. Doping MoO3 with Fe and Co increases emission in the visible range due to an increase number of chemisorbed oxygen atoms. The photodegradation of an aqueous solution of methylene blue (MB) depended on the content of the codoping elements (Fe,Co). The results showed that a degradation efficiency of 90% was observed after 60 min for MoO3: Fe 2%-Co 1%, while the degradation efficiency was about 35% for the undoped MoO3 thin film.
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Affiliation(s)
- Olfa Kamoun
- Department of Physics, University of Tunis El Manar, 2092 Tunis, Tunisia.
| | - Amel Mami
- UR Photothermy, Photothermal Laboratory, Preparatory Institute for Engineering Studies of Nabeul (IPEIN), 8000 Merazka, Nabeul, Tunisia.
| | | | - Ruxandra Vidu
- Department of Electrical Engineering and Computer Science, University of California, Davis, CA 95616, USA.
- Faculty of Materials Sciences, University Politehnica of Bucharest, UPB-ECOMET, 011061 Bucharest, Romania.
| | - Mosbah Amlouk
- Department of Physics, University of Tunis El Manar, 2092 Tunis, Tunisia.
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Zhao X, Yang H, Li R, Cui Z, Liu X. Synthesis of heterojunction photocatalysts composed of Ag 2 S quantum dots combined with Bi 4 Ti 3 O 12 nanosheets for the degradation of dyes. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:5524-5538. [PMID: 30607858 DOI: 10.1007/s11356-018-4050-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 12/19/2018] [Indexed: 06/09/2023]
Abstract
Facilitating the separation of photogenerated electron/hole pairs and widening the light-responsive region are crucial to enhance the overall photocatalytic performance of photocatalysts. To achieve this aim, here we have prepared Ag2S/Bi4Ti3O12 heterojunction composite photocatalysts by assembling Ag2S quantum dots onto the surface of Bi4Ti3O12 nanosheets. Transmission electron microscopy observation demonstrates that two types of Ag2S quantum dots separately with size of 40-70 and 7-17 nm are uniformly assembled onto the surface of large-sized Bi4Ti3O12 thin nanosheets. The as-prepared Ag2S/Bi4Ti3O12 heterojunction composites exhibit much enhanced light absorption (particularly in the visible and near-infrared region) and highly efficient separation of electrons and holes photogenerated in Bi4Ti3O12. Rhodamine B (RhB) aqueous solution was chosen as the target organic pollutant to evaluate the photocatalytic performance of the samples under simulated sunlight irradiation. It is found that the Ag2S/Bi4Ti3O12 heterojunction composites manifest significantly enhanced photocatalytic activity toward the RhB degradaton. In particular, the 15wt% Ag2S/Bi4Ti3O12 composite exhibits the highest photocatalytic activity, which is ca. 2.8 and 4.0 times higher than bare Bi4Ti3O12 and Ag2S, respectively. The enhanced photocatalytic activity of the composites can be explained as a result of the Z-scheme electron transfer from the conduction band of Bi4Ti3O12 to the valence band of Ag2S, and thus more photogenerated holes in the valence band of Bi4Ti3O12 and electrons in the conduction band of Ag2S are able to participate in the photocatalytic reactions. Active species trapping experiments were carried out, from which it is concluded that photogenerated holes and •O2- radicals play the dominant and secondary role in the photocatalysis, respectively.
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Affiliation(s)
- Xinxin Zhao
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou, 730050, China
- School of Science, Lanzhou University of Technology, Lanzhou, 730050, China
| | - Hua Yang
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou, 730050, China.
- School of Science, Lanzhou University of Technology, Lanzhou, 730050, China.
| | - Ruishan Li
- School of Science, Lanzhou University of Technology, Lanzhou, 730050, China
| | - Ziming Cui
- School of Science, Lanzhou University of Technology, Lanzhou, 730050, China
| | - Xueqin Liu
- School of Science, Chongqing University of Technology, Chongqing, 4000054, China
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Zhao X, Yang H, Cui Z, Wang X, Yi Z. Growth Process and CQDs-modified Bi₄Ti₃O 12 Square Plates with Enhanced Photocatalytic Performance. MICROMACHINES 2019; 10:E66. [PMID: 30669287 PMCID: PMC6356592 DOI: 10.3390/mi10010066] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 01/09/2019] [Accepted: 01/16/2019] [Indexed: 11/16/2022]
Abstract
Bi₄Ti₃O12 square plates were synthesized via a hydrothermal route, and their growth process was systematically investigated. Carbon quantum dots (CQDs) were prepared using glucose as the carbon source, which were then assembled on the surface of Bi₄Ti₃O12 square plates via a hydrothermal route with the aim of enhancing the photocatalytic performance. XRD (X-ray powder diffraction), SEM (scanning electron microscopy), TEM (transmission electron microscopy), UV-vis DRS (diffuse reflectance spectroscopy), XPS (X-ray photoelectron spectroscopy), FTIR (Fourier transform infrared spectroscopy), PL (photoluminescence) spectroscopy, EIS (electrochemical impedance spectroscopy) and photocurrent spectroscopy were used to systematically characterize the as-prepared samples. It is demonstrated that the decoration of CQDs on Bi₄Ti₃O12 plates leads to an increased visible light absorption, slightly increased bandgap, increased photocurrent density, decreased charge-transfer resistance, and decreased PL intensity. Simulated sunlight and visible light were separately used as a light source to evaluate the photocatalytic activity of the samples toward the degradation of RhB in aqueous solution. Under both simulated sunlight and visible light irradiation, CQDs@Bi₄Ti₃O12 composites with an appropriate amount of CQDs exhibit obviously enhanced photocatalytic performance. However, the decoration of excessive CQDs gives rise to a decrease in the photocatalytic activity. The enhanced photocatalytic activity of CQDs-modified Bi₄Ti₃O12 can be attributed to the following reasons: (1) The electron transfer between Bi₄Ti₃O12 and CQDs promotes an efficient separation of photogenerated electron/hole pairs in Bi₄Ti₃O12; (2) the up-conversion photoluminescence emitted from CQDs could induce the generation of additional electron/hole pairs in Bi₄Ti₃O12; and (3) the photoexcited electrons in CQDs could participate in the photocatalytic reactions.
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Affiliation(s)
- Xinxin Zhao
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China.
| | - Hua Yang
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China.
| | - Ziming Cui
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China.
| | - Xiangxian Wang
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China.
| | - Zao Yi
- Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology, Mianyang 621010, China.
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