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Tinoco Navarro LK, Jaroslav C. Enhancing Photocatalytic Properties of TiO 2 Photocatalyst and Heterojunctions: A Comprehensive Review of the Impact of Biphasic Systems in Aerogels and Xerogels Synthesis, Methods, and Mechanisms for Environmental Applications. Gels 2023; 9:976. [PMID: 38131962 PMCID: PMC10742597 DOI: 10.3390/gels9120976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 11/30/2023] [Accepted: 12/03/2023] [Indexed: 12/23/2023] Open
Abstract
This review provides a detailed exploration of titanium dioxide (TiO2) photocatalysts, emphasizing structural phases, heterophase junctions, and their impact on efficiency. Key points include diverse synthesis methods, with a focus on the sol-gel route and variants like low-temperature hydrothermal synthesis (LTHT). The review delves into the influence of acid-base donors on gelation, dissects crucial drying techniques for TiO2 aerogel or xerogel catalysts, and meticulously examines mechanisms underlying photocatalytic activity. It highlights the role of physicochemical properties in charge diffusion, carrier recombination, and the impact of scavengers in photo-oxidation/reduction. Additionally, TiO2 doping techniques and heterostructures and their potential for enhancing efficiency are briefly discussed, all within the context of environmental applications.
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Affiliation(s)
- Lizeth Katherine Tinoco Navarro
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 656/123, 612 00 Brno, Czech Republic;
| | - Cihlar Jaroslav
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 656/123, 612 00 Brno, Czech Republic;
- Institute of Materials Science and Engineering, Brno University of Technology, Technicka 2, 616 69 Brno, Czech Republic
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Lizeth Katherine TN, Vendula B, Jaroslav K, Jaroslav C. Structure and Photocatalytic Properties of Ni-, Co-, Cu-, and Fe-Doped TiO 2 Aerogels. Gels 2023; 9:gels9050357. [PMID: 37232949 DOI: 10.3390/gels9050357] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/19/2023] [Accepted: 04/20/2023] [Indexed: 05/27/2023] Open
Abstract
TiO2 aerogels doped with Ni, Co, Cu, and Fe were prepared, and their structure and photocatalytic activity during the decomposition of a model pollutant, acid orange (AO7), were studied. After calcination at 500 °C and 900 °C, the structure and composition of the doped aerogels were evaluated and analyzed. XRD analysis revealed the presence of anatase/brookite and rutile phases in the aerogels along with other oxide phases from the dopants. SEM and TEM microscopy showed the nanostructure of the aerogels, and BET analysis showed their mesoporosity and high specific surface area of 130 to 160 m2·g-1. SEM-EDS, STEM-EDS, XPS, EPR methods and FTIR analysis evaluated the presence of dopants and their chemical state. The concentration of doped metals in aerogels varied from 1 to 5 wt.%. The photocatalytic activity was evaluated using UV spectrophotometry and photodegradation of the AO7 pollutant. Ni-TiO2 and Cu-TiO2 aerogels calcined at 500 °C showed higher photoactivity coefficients (kaap) than aerogels calcined at 900 °C, which were ten times less active due to the transformation of anatase and brookite to the rutile phase and the loss of textural properties of the aerogels.
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Affiliation(s)
- Tinoco Navarro Lizeth Katherine
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 656/123, 612 00 Brno, Czech Republic
| | - Bednarikova Vendula
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 656/123, 612 00 Brno, Czech Republic
| | - Kastyl Jaroslav
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 656/123, 612 00 Brno, Czech Republic
| | - Cihlar Jaroslav
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 656/123, 612 00 Brno, Czech Republic
- Institute of Materials Science and Engineering, Brno University of Technology, Technicka 2, 616 69 Brno, Czech Republic
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Qaid SMH, Ghaithan HM, Bawazir HS, Bin Ajaj AF, AlHarbi KK, Aldwayyan AS. Successful Growth of TiO 2 Nanocrystals with {001} Facets for Solar Cells. Nanomaterials (Basel) 2023; 13:928. [PMID: 36903806 PMCID: PMC10005624 DOI: 10.3390/nano13050928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 02/28/2023] [Accepted: 03/02/2023] [Indexed: 06/18/2023]
Abstract
The growth of nanocrystals (NCs) from metal oxide-based substrates with exposed high-energy facets is of particular importance for many important applications, such as solar cells as photoanodes due to the high reactivity of these facets. The hydrothermal method remains a current trend for the synthesis of metal oxide nanostructures in general and titanium dioxide (TiO2) in particular since the calcination of the resulting powder after the completion of the hydrothermal method no longer requires a high temperature. This work aims to use a rapid hydrothermal method to synthesize numerous TiO2-NCs, namely, TiO2 nanosheets (TiO2-NSs), TiO2 nanorods (TiO2-NRs), and nanoparticles (TiO2-NPs). In these ideas, a simple non-aqueous one-pot solvothermal method was employed to prepare TiO2-NSs using tetrabutyl titanate Ti(OBu)4 as a precursor and hydrofluoric acid (HF) as a morphology control agent. Ti(OBu)4 alone was subjected to alcoholysis in ethanol, yielding only pure nanoparticles (TiO2-NPs). Subsequently, in this work, the hazardous chemical HF was replaced by sodium fluoride (NaF) as a means of controlling morphology to produce TiO2-NRs. The latter method was required for the growth of high purity brookite TiO2 NRs structure, the most difficult TiO2 polymorph to synthesize. The fabricated components are then morphologically evaluated using equipment, such as transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), electron diffraction (SAED), and X-ray diffraction (XRD). In the results, the TEM image of the developed NCs shows the presence of TiO2-NSs with an average side length of about 20-30 nm and a thickness of 5-7 nm. In addition, the image TEM shows TiO2-NRs with diameters between 10 and 20 nm and lengths between 80 and 100 nm, together with crystals of smaller size. The phase of the crystals is good, confirmed by XRD. The anatase structure, typical of TiO2-NS and TiO2-NPs, and the high-purity brookite-TiO2-NRs structure, were evident in the produced nanocrystals, according to XRD. SAED patterns confirm that the synthesis of high quality single crystalline TiO2-NSs and TiO2-NRs with the exposed {001} facets are the exposed facets, which have the upper and lower dominant facets, high reactivity, high surface energy, and high surface area. TiO2-NSs and TiO2-NRs could be grown, corresponding to about 80% and 85% of the {001} outer surface area in the nanocrystal, respectively.
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Affiliation(s)
- Saif M. H. Qaid
- Department of Physics & Astronomy, College of Sciences, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
- K. A. CARE Energy Research and Innovation Center, King Saud University, Riyadh 11451, Saudi Arabia
| | - Hamid M. Ghaithan
- Department of Physics & Astronomy, College of Sciences, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
| | - Huda S. Bawazir
- Department of Physics & Astronomy, College of Sciences, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
- K. A. CARE Energy Research and Innovation Center, King Saud University, Riyadh 11451, Saudi Arabia
| | - Abrar F. Bin Ajaj
- Department of Physics & Astronomy, College of Sciences, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
- K. A. CARE Energy Research and Innovation Center, King Saud University, Riyadh 11451, Saudi Arabia
| | - Khulod K. AlHarbi
- Department of Physics & Astronomy, College of Sciences, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
- K. A. CARE Energy Research and Innovation Center, King Saud University, Riyadh 11451, Saudi Arabia
| | - Abdullah S. Aldwayyan
- Department of Physics & Astronomy, College of Sciences, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
- K. A. CARE Energy Research and Innovation Center, King Saud University, Riyadh 11451, Saudi Arabia
- King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451, Saudi Arabia
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Mancuso A, Blangetti N, Sacco O, Freyria FS, Bonelli B, Esposito S, Sannino D, Vaiano V. Photocatalytic Degradation of Crystal Violet Dye under Visible Light by Fe-Doped TiO 2 Prepared by Reverse-Micelle Sol-Gel Method. Nanomaterials (Basel) 2023; 13:nano13020270. [PMID: 36678023 PMCID: PMC9861999 DOI: 10.3390/nano13020270] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 12/26/2022] [Accepted: 01/04/2023] [Indexed: 05/31/2023]
Abstract
A reverse-micelle sol-gel method was chosen for the preparation of Fe-doped TiO2 samples that were employed in the photodegradation of the crystal violet dye under visible light irradiation in a batch reactor. The dopant amount was varied to assess the optimal photocatalyst composition towards the target dye degradation. The photocatalysts were characterized through a multi-technique approach, envisaging XRPD and QPA as obtained by Rietveld refinement, FE-SEM analysis, DR UV-vis spectroscopy, N2 adsorption/desorption isotherms measurement at -196 °C, ζ-potential measurement, and XPS analysis. The physical-chemical characterization showed that the adopted synthesis method allows obtaining NPs with uniform shape and size and promotes the introduction of Fe into the titania matrix, finally affecting the relative amounts of the three occurring polymorphs of TiO2 (anatase, rutile and brookite). By increasing the Fe content, the band gap energy decreases from 3.13 eV (with undoped TiO2) to 2.65 eV (with both 2.5 and 3.5 wt.% nominal Fe contents). At higher Fe content, surface Fe oxo-hydroxide species occur, as shown by DR UV-vis and XP spectroscopies. All the Fe-doped TiO2 photocatalysts were active in the degradation and mineralization of the target dye, showing a TOC removal higher than the undoped sample. The photoactivity under visible light was ascribed both to the band-gap reduction (as confirmed by phenol photodegradation) and to dye sensitization of the photocatalyst surface (as confirmed by photocatalytic tests carried out using different visible-emission spectra LEDs). The main reactive species involved in the dye degradation were determined to be positive holes.
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Affiliation(s)
- Antonietta Mancuso
- Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano, Italy
| | - Nicola Blangetti
- Department of Applied Science and Technology and INSTM Unit of Torino Politecnico, Corso Duca Degli Abruzzi 24, 10129 Torino, Italy
| | - Olga Sacco
- Department of Chemistry and Biology “A. Zambelli” and INSTM Research Unit, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Italy
| | - Francesca Stefania Freyria
- Department of Applied Science and Technology and INSTM Unit of Torino Politecnico, Corso Duca Degli Abruzzi 24, 10129 Torino, Italy
| | - Barbara Bonelli
- Department of Applied Science and Technology and INSTM Unit of Torino Politecnico, Corso Duca Degli Abruzzi 24, 10129 Torino, Italy
- Interdepartmental Centre PolitoBIOMed Lab., Corso Duca Degli Abruzzi 24, 10129 Torino, Italy
| | - Serena Esposito
- Department of Applied Science and Technology and INSTM Unit of Torino Politecnico, Corso Duca Degli Abruzzi 24, 10129 Torino, Italy
| | - Diana Sannino
- Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano, Italy
| | - Vincenzo Vaiano
- Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano, Italy
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Yang J, Wang J, Yang W, Zhu Y, Feng S, Su P, Fu W. Low-Temperature Processed Brookite Interfacial Modification for Perovskite Solar Cells with Improved Performance. Nanomaterials (Basel) 2022; 12:nano12203653. [PMID: 36296841 PMCID: PMC9608627 DOI: 10.3390/nano12203653] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/14/2022] [Accepted: 10/14/2022] [Indexed: 06/12/2023]
Abstract
The scaffold layer plays an important role in transporting electrons and preventing carrier recombination in mesoporous perovskite solar cells (PSCs), so the engineering of the interface between the scaffold layer and the light absorption layer has attracted widespread concern. In this work, vertically grown TiO2 nanorods (NRs) as scaffold layers are fabricated and further treated with TiCl4 aqueous solution. It can be found that a thin brookite TiO2 nanoparticle (NP) layer is formed by the chemical bath deposition (CBD) method on the surface of every rutile NR with a low annealing temperature (150 °C), which is beneficial for the infiltration and growth of perovskite. The PSC based on the TiO2 NR/brookite NP structure shows the best power conversion of 15.2%, which is 56.37% higher than that of the PSC based on bare NRs (9.72%). This complex structure presents an improved pore filling fraction and better carrier transport capability with less trap-assisted carrier recombination. In addition, low-annealing-temperature-formed brookite NPs possess a more suitable edge potential for electrons to transport from the perovskite layer to the electron collection layer when compared with high-annealing-temperature-formed anatase NPs. The brookite phase TiO2 fabricated at a low temperature presents great potential for flexible PSCs.
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Affiliation(s)
- Jiandong Yang
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China
| | - Jun Wang
- School of Physics and Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, China
| | - Wenshu Yang
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China
| | - Ying Zhu
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China
| | - Shuang Feng
- College of Mathmatics and Physics, Inner Mongolia Minzu University, Tongliao 028000, China
| | - Pengyu Su
- School of Electronic Information Engineering, Yangtze Normal University, Chongqing 408100, China
| | - Wuyou Fu
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China
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Kremenović A, Grujić-Brojčin M, Tomić N, Lazović V, Bajuk-Bogdanović D, Krstić J, Šćepanović M. Size-strain line-broadening analysis of anatase/ brookite (TiO 2)-based nanocomposites with carbon (C): XRPD and Raman spectroscopic analysis. Acta Crystallogr B Struct Sci Cryst Eng Mater 2022; 78:214-222. [PMID: 35411859 DOI: 10.1107/s2052520622001731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 02/15/2022] [Indexed: 06/14/2023]
Abstract
A size-strain line-broadening analysis of the XRPD patterns and Raman spectra for two anatase/brookite (TiO2)-based nanocomposites with carbon (C) was carried out and the results compared with those of a similar sample free of carbon. The crystal structures and microstructures of anatase and brookite, as well as their relative abundance ratio, have been refined from XRPD data by the Rietveld method (the low amount of carbon is neglected). The XRPD size-strain analysis resulted in reliable structure and microstructure results for both anatase and brookite. The experimental Raman spectra of all the samples in the region 100-200 cm-1 are dominated by a strong feature primarily composed of the most intense modes of anatase (Eg) and brookite (A1g). The anatase crystallite sizes of 14-17 nm, estimated by XRPD, suggest the application of the phonon confinement model (PCM) for the analysis of the anatase Eg mode, whereas the relatively large brookite crystallite size (27-29 nm) does not imply the use of the PCM for the brookite A1g mode. Superposition of the anatase Eg mode profile, calculated by the PCM, and the Lorentzian shape of the brookite A1g mode provide an appropriate simulation of the change in the dominant Raman feature in the spectra of TiO2-based nanocomposites with carbon. Raman spectra measured in the high-frequency range (1000-2000 cm-1) provide information on carbon in the investigated nanocomposite materials. The results from field-emission scanning electron microscope (SEM), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy and nitrogen physisorption measurements support the XRPD and Raman results.
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Affiliation(s)
- Aleksandar Kremenović
- Faculty of Mining and Geology, University of Belgrade, Đušina 7, Belgrade 11000, Serbia
| | - Mirjana Grujić-Brojčin
- Center for Solid State Physics and New Materials, Institute of Physics, University of Belgrade, Pregrevica 118, Belgrade 11000, Serbia
| | - Nataša Tomić
- Center for Solid State Physics and New Materials, Institute of Physics, University of Belgrade, Pregrevica 118, Belgrade 11000, Serbia
| | - Vladimir Lazović
- Photonics Center, Institute of Physics, University of Belgrade, Pregrevica 118, Belgrade 11000, Serbia
| | - Danica Bajuk-Bogdanović
- Faculty of Physical Chemistry, University of Belgrade, Studentski Trg 12-16, Belgrade 11000, Serbia
| | - Jugoslav Krstić
- Department of Catalysis and Chemical Engineering, Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Njegoševa 12, Belgrade 11000, Serbia
| | - Maja Šćepanović
- Center for Solid State Physics and New Materials, Institute of Physics, University of Belgrade, Pregrevica 118, Belgrade 11000, Serbia
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Freyria FS, Blangetti N, Esposito S, Nasi R, Armandi M, Annelio V, Bonelli B. Effects of the Brookite Phase on the Properties of Different Nanostructured TiO 2 Phases Photocatalytically Active Towards the Degradation of N-Phenylurea. ChemistryOpen 2020; 9:903-912. [PMID: 32908812 PMCID: PMC7464118 DOI: 10.1002/open.202000127] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 07/17/2020] [Indexed: 11/30/2022] Open
Abstract
Different sol-gel synthesis methods were used to obtain four nanostructured mesoporous TiO2 samples for an efficient photocatalytic degradation of the emerging contaminant N-phenylurea under either simulated solar light (1 Sun) or UV light. Particularly, two TiO2 samples were obtained by means of as many template-assisted syntheses, whereas other two TiO2 samples were obtained by a greener template-free procedure, implying acidic conditions and, then, calcination at either 200 °C or 600 °C. In one case, anatase was obtained, whereas in the other three cases mixed crystalline phases were obtained. The four TiO2 samples were characterized by X-ray powder diffraction (followed by Rietveld analysis); Transmission Electron Microscopy; N2 adsorption/desorption at -196 °C; Diffuse Reflectance UV/Vis spectroscopy and ζ-potential measurements. A commercial TiO2 powder (i. e., Degussa P25) was used for comparison. Differences among the synthesized samples were observed not only in their quantitative phase composition, but also in their nanoparticles morphology (shape and size), specific surface area, pore size distribution and pHIEP (pH at isoelectric point), whereas the samples band-gap did not vary sizably. The samples showed different photocatalytic behavior in terms of N-phenylurea degradation, which are ascribed to their different physico-chemical properties and, especially, to their phase composition, stemming from the different synthesis conditions.
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Affiliation(s)
- Francesca S. Freyria
- Department of Applied Science and Technology and INSTMUnit of Torino PolitecnicoPolitecnico di TorinoCorso Duca degli Abruzzi 2410129TorinoItaly
- Department of ChemistryMassachusetts Institute of Technology77 Massachusetts AvenueCambridgeMA02139USA
| | - Nicola Blangetti
- Department of Applied Science and Technology and INSTMUnit of Torino PolitecnicoPolitecnico di TorinoCorso Duca degli Abruzzi 2410129TorinoItaly
| | - Serena Esposito
- Department of Applied Science and Technology and INSTMUnit of Torino PolitecnicoPolitecnico di TorinoCorso Duca degli Abruzzi 2410129TorinoItaly
| | - Roberto Nasi
- Department of Applied Science and Technology and INSTMUnit of Torino PolitecnicoPolitecnico di TorinoCorso Duca degli Abruzzi 2410129TorinoItaly
| | - Marco Armandi
- Department of Applied Science and Technology and INSTMUnit of Torino PolitecnicoPolitecnico di TorinoCorso Duca degli Abruzzi 2410129TorinoItaly
| | - Vincenzo Annelio
- Department of Applied Science and Technology and INSTMUnit of Torino PolitecnicoPolitecnico di TorinoCorso Duca degli Abruzzi 2410129TorinoItaly
| | - Barbara Bonelli
- Department of Applied Science and Technology and INSTMUnit of Torino PolitecnicoPolitecnico di TorinoCorso Duca degli Abruzzi 2410129TorinoItaly
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Khedr TM, El-Sheikh SM, Ismail AA, Kowalska E, Bahnemann DW. Photodegradation of Microcystin-LR Using Visible Light-Activated C/N-co-Modified Mesoporous TiO₂ Photocatalyst. Materials (Basel) 2019; 12:ma12071027. [PMID: 30925688 PMCID: PMC6480059 DOI: 10.3390/ma12071027] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 03/21/2019] [Accepted: 03/22/2019] [Indexed: 11/16/2022]
Abstract
Microcystin-LR (MC-LR), a potent hepatotoxin produced by the cyanobacteria, is of increasing concern worldwide because of severe and persistent impacts on humans and animals by inhalation and consumption of contaminated waters and food. In this work, MC-LR was removed completely from aqueous solution using visible-light-active C/N-co-modified mesoporous anatase/brookite TiO₂ photocatalyst. The co-modified TiO₂ nanoparticles were synthesized by a one-pot hydrothermal process, and then calcined at different temperatures (300, 400, and 500 °C). All the obtained TiO₂ powders were analyzed by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscope (TEM), specific surface area (SSA) measurements, ultraviolet-visible diffuse reflectance spectra (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and photoluminescence (PL) analysis. It was found that all samples contained mixed-phase TiO₂ (anatase and brookite), and the content of brookite decreased with an increase in calcination temperature, as well as the specific surface area and the content of non-metal elements. The effects of initial pH value, the TiO₂ content, and MC-LR concentration on the photocatalytic activity were also studied. It was found that the photocatalytic activity of the obtained TiO₂ photocatalysts declined with increasing temperature. The complete degradation (100%) of MC-LR (10 mg L-1) was observed within 3 h, using as-synthesized co-modified TiO₂ (0.4 g L-1) at pH 4 under visible light. Based on the obtained results, the mechanism of MC-LR degradation has been proposed.
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Affiliation(s)
- Tamer M Khedr
- Nanomaterials and Nanotechnology Department, Central Metallurgical Research and Development Institute (CMRDI) P.O. Box: 87 Helwan, Cairo 11421, Egypt.
- Institute of Technical Chemistry, Photocatalysis and Nanotechnology Research Unit, Leibniz Universität Hannover, Callinstr. 3, D-30167 Hannover, Germany.
- Institute for Catalysis, Hokkaido University, N21, W10, Sapporo 001-0021, Japan.
| | - Said M El-Sheikh
- Nanomaterials and Nanotechnology Department, Central Metallurgical Research and Development Institute (CMRDI) P.O. Box: 87 Helwan, Cairo 11421, Egypt.
| | - Adel A Ismail
- Nanomaterials and Nanotechnology Department, Central Metallurgical Research and Development Institute (CMRDI) P.O. Box: 87 Helwan, Cairo 11421, Egypt.
- Nanotechnology and Advanced Materials Program, Energy & Building Research Center (EBRC), Kuwait Institute for Scientific Research (KISR), P.O. Box 24885, Safat 13109, Kuwait.
| | - Ewa Kowalska
- Institute for Catalysis, Hokkaido University, N21, W10, Sapporo 001-0021, Japan.
| | - Detlef W Bahnemann
- Institute of Technical Chemistry, Photocatalysis and Nanotechnology Research Unit, Leibniz Universität Hannover, Callinstr. 3, D-30167 Hannover, Germany.
- Laboratory "Photoactive Nanocomposite Materials" (Director), Saint-Petersburg State University, Ulyanovskaya str. 1, Peterhof, Saint-Petersburg 198504, Russia.
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Choi M, Lim J, Baek M, Choi W, Kim W, Yong K. Investigating the Unrevealed Photocatalytic Activity and Stability of Nanostructured Brookite TiO 2 Film as an Environmental Photocatalyst. ACS Appl Mater Interfaces 2017; 9:16252-16260. [PMID: 28459533 DOI: 10.1021/acsami.7b03481] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Among three polymorphs of TiO2, the brookite is the least known phase in many aspects of its properties and photoactivities (especially comparable to anatase and rutile) because it is the rarest phase to be synthesized in the standard environment among the TiO2 polymorphs. In this study, we address the unrevealed photocatalytic properties of pure brookite TiO2 film as an environmental photocatalyst. Highly crystalline brookite nanostructures were synthesized on titanium foil using a well-designed hydrothermal reaction, without harmful precursors and selective etching of anatase, to afford pure brookite. The photocatalytic degradation of rhodamine B, tetramethylammonium chloride, and 4-chlorophenol on UV-illuminated pure brookite were investigated and compared with those on anatase and rutile TiO2. The present research explores the generation of OH radicals as main oxidants on brookite. In addition, tetramethylammonium, as a mobile OH radical indicator, was degraded over both pure anatase and brookite phases, but not rutile. The brookite phase showed much higher photoactivity among TiO2 polymorphs, despite its smaller surface area compared with anatase. This result can be ascribed to the following properties of the brookite TiO2 film: (i) the higher driving force with more negative flat-band potential, (ii) the efficient charge transfer kinetics with low resistance, and (iii) the generation of more hydroxyl radicals, including mobile OH radicals. The brookite-nanostructured TiO2 electrode facilitates photocatalyst collection and recycling with excellent stability, and readily controls photocatalytic degradation rates with facile input of additional potential.
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Affiliation(s)
| | | | | | | | - Wooyul Kim
- Department of Chemical and Biological Engineering, College of Engineering, Sookmyung Women's University , Seoul, 04310, Republic of Korea
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Cargnello M, Montini T, Smolin SY, Priebe JB, Delgado Jaén JJ, Doan-Nguyen VV, McKay IS, Schwalbe JA, Pohl MM, Gordon TR, Lu Y, Baxter JB, Brückner A, Fornasiero P, Murray CB. Engineering titania nanostructure to tune and improve its photocatalytic activity. Proc Natl Acad Sci U S A 2016; 113:3966-71. [PMID: 27035977 DOI: 10.1073/pnas.1524806113] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Photocatalytic pathways could prove crucial to the sustainable production of fuels and chemicals required for a carbon-neutral society. Electron-hole recombination is a critical problem that has, so far, limited the efficiency of the most promising photocatalytic materials. Here, we show the efficacy of anisotropy in improving charge separation and thereby boosting the activity of a titania (TiO2) photocatalytic system. Specifically, we show that H2 production in uniform, one-dimensional brookite titania nanorods is highly enhanced by engineering their length. By using complimentary characterization techniques to separately probe excited electrons and holes, we link the high observed reaction rates to the anisotropic structure, which favors efficient carrier utilization. Quantum yield values for hydrogen production from ethanol, glycerol, and glucose as high as 65%, 35%, and 6%, respectively, demonstrate the promise and generality of this approach for improving the photoactivity of semiconducting nanostructures for a wide range of reacting systems.
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