1
|
Mintcheva N, Subbiah DK, Turabayev ME, Gurbatov SO, Rayappan JBB, Kuchmizhak AA, Kulinich SA. Gas Sensing of Laser-Produced Hybrid TiO 2-ZnO Nanomaterials under Room-Temperature Conditions. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:670. [PMID: 36839038 PMCID: PMC9965002 DOI: 10.3390/nano13040670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 02/04/2023] [Accepted: 02/06/2023] [Indexed: 06/18/2023]
Abstract
The preparation method can considerably affect the structural, morphological, and gas-sensing properties of mixed-oxide materials which often demonstrate superior photocatalytic and sensing performance in comparison with single-metal oxides. In this work, hybrids of semiconductor nanomaterials based on TiO2 and ZnO were prepared by laser ablation of Zn and Ti plates in water and then tested as chemiresistive gas sensors towards volatile organics (2-propanol, acetaldehyde, ethanol, methanol) and ammonia. An infrared millisecond pulsed laser with energy 2.0 J/pulse and a repetition rate of 5 Hz was applied to Zn and Ti metal targets in different ablation sequences to produce two nano-hybrids (TiO2/ZnO and ZnO/TiO2). The surface chemistry, morphology, crystallinity, and phase composition of the prepared hybrids were found to tune their gas-sensing properties. Among all tested gases, sample TiO2/ZnO showed selectivity to ethanol, while sample ZnO/TiO2 sensed 2-propanol at room temperature, both with a detection limit of ~50 ppm. The response and recovery times were found to be 24 and 607 s for the TiO2/ZnO sensor, and 54 and 50 s for its ZnO/TiO2 counterpart, respectively, towards 100 ppm of the target gas at room temperature.
Collapse
Affiliation(s)
- Neli Mintcheva
- Research Institute of Science and Technology, Tokai University, Hiratsuka 259-1292, Kanagawa, Japan
- Department of Chemistry, University of Mining and Geology, 1700 Sofia, Bulgaria
| | - Dinesh Kumar Subbiah
- Centre for Nanotechnology & Advanced Biomaterials (CeNTAB), School of Electrical & Electronics Engineering, SASTRA Deemed University, Thanjavur 613 401, Tamil Nadu, India
| | - Marat E. Turabayev
- Department of Mechanical Engineering, Tokai University, Hiratsuka 259-1292, Kanagawa, Japan
| | - Stanislav O. Gurbatov
- Far Eastern Federal University, 690041 Vladivostok, Russia
- Institute of Automation and Control Processes, Far Eastern Branch of the Russian Academy of Science, 690091 Vladivostok, Russia
| | - John Bosco Balaguru Rayappan
- Centre for Nanotechnology & Advanced Biomaterials (CeNTAB), School of Electrical & Electronics Engineering, SASTRA Deemed University, Thanjavur 613 401, Tamil Nadu, India
| | - Aleksandr A. Kuchmizhak
- Far Eastern Federal University, 690041 Vladivostok, Russia
- Institute of Automation and Control Processes, Far Eastern Branch of the Russian Academy of Science, 690091 Vladivostok, Russia
| | - Sergei A. Kulinich
- Research Institute of Science and Technology, Tokai University, Hiratsuka 259-1292, Kanagawa, Japan
- Department of Mechanical Engineering, Tokai University, Hiratsuka 259-1292, Kanagawa, Japan
| |
Collapse
|
2
|
Mintcheva N, Yamaguchi S, Kulinich SA. Hybrid TiO 2-ZnO Nanomaterials Prepared Using Laser Ablation in Liquid. MATERIALS 2020; 13:ma13030719. [PMID: 32033417 PMCID: PMC7040934 DOI: 10.3390/ma13030719] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Revised: 02/01/2020] [Accepted: 02/03/2020] [Indexed: 12/23/2022]
Abstract
Hybrids of semiconductor nanomaterials often demonstrate properties that are superior to those of their components. In this study, we prepared hybrid nanomaterials of TiO2 and ZnO, which are among the most actively studied semiconductors, by means of millisecond-pulsed laser and analyzed how their morphology, particle size, and surface composition depend on preparation conditions. A series of nanomaterials were obtained via sequentially ablating Zn and Ti metal plates (in different sequences) in water, while laser pulses of lower (2.0 J/pulse) and higher (5.0 J/pulse) energy were applied. The properties of laser-produced hybrid TiO2-ZnO nanomaterials were shown to be governed by experimental conditions such as laser pulse width, pulse peak power, and reaction media (either pure water or colloid with nanoparticles). The morphology revealed nanospheres of TiO2 that decorate nanorods of ZnO or flower-like aggregates of zinc oxide. Intriguingly, after extended ablation time, titania was found to be self-doped with Ti3+ and Ti2+ ions, and the contribution of lower oxidation states of titanium could be controlled by the applied laser pulse energy. The physicochemical characteristics of hybrid nanomaterials were compared with pure ZnO and TiO2 prepared under the same laser conditions.
Collapse
Affiliation(s)
- Neli Mintcheva
- Research Institute of Science and Technology, Tokai University, Hiratsuka, Kanagawa 259-1292, Japan
- Department of Chemistry, University of Mining and Geology, 1700 Sofia, Bulgaria
- Correspondence: (N.M.); (S.K.)
| | - Shigeru Yamaguchi
- Department of Physics, Tokai University, Hiratsuka, Kanagawa 259-1292, Japan;
| | - Sergei A. Kulinich
- Research Institute of Science and Technology, Tokai University, Hiratsuka, Kanagawa 259-1292, Japan
- Department of Mechanical Engineering, Tokai University, Hiratsuka, Kanagawa 259-1292, Japan
- School of Natural Sciences, Far Eastern Federal University, 690041 Vladivostok, Russia
- Correspondence: (N.M.); (S.K.)
| |
Collapse
|
3
|
Wei Z, Janczarek M, Endo M, Wang K, Balčytis A, Nitta A, Méndez-Medrano MG, Colbeau-Justin C, Juodkazis S, Ohtani B, Kowalska E. Noble metal-modified faceted anatase titania photocatalysts: Octahedron versus decahedron. APPLIED CATALYSIS. B, ENVIRONMENTAL 2018; 237:574-587. [PMID: 30532348 PMCID: PMC6100264 DOI: 10.1016/j.apcatb.2018.06.027] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 06/03/2018] [Accepted: 06/09/2018] [Indexed: 05/23/2023]
Abstract
Octahedral anatase particles (OAP, with eight equivalent {101} facets) and decahedral anatase particles (DAP, with two additional {001} facets) were modified with nanoparticles of noble metals (Au, Ag, Cu). The titania morphology, expressed by the presence of different arrangements of exposed crystal facets, played a key role in the photocatalytic properties of metal-modified faceted titania. In the UV/vis systems, two-faceted configuration of DAP was more favorable for the reaction efficiency than single-faceted OAP because of an efficient charge separation described by the transfer of electrons to {101} facets and holes to {001} facets. Time-resolved microwave conductivity (TRMC) and reversed double-beam photoacoustic spectroscopy (RDB-PAS) confirmed that distribution of electron traps (ET) and mobility of electrons were key-factors of photocatalytic activity. In contrast, metal-modified OAP samples had higher photocatalytic activity than metal-modified DAP and metal-modified commercial titania samples under visible light irradiation. This indicates that the presence of single type of facets ({101}) is favorable for efficient electron transfer via shallow ET, whereas intrinsic properties of DAP result in fast charge carriers' recombination when gold is deposited on {101} facets (migration of "hot" electrons: Au→{101}→Au).
Collapse
Affiliation(s)
- Zhishun Wei
- Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan, 430068, China
- Institute for Catalysis, Hokkaido University, N21, W8, 001-0021, Sapporo, Japan
| | - Marcin Janczarek
- Institute for Catalysis, Hokkaido University, N21, W8, 001-0021, Sapporo, Japan
- Department of Chemical Technology, Gdansk University of Technology, G. Narutowicza 11/12, 80-233, Gdansk, Poland
| | - Maya Endo
- Institute for Catalysis, Hokkaido University, N21, W8, 001-0021, Sapporo, Japan
| | - Kunlei Wang
- Institute for Catalysis, Hokkaido University, N21, W8, 001-0021, Sapporo, Japan
| | - Armandas Balčytis
- Center for Micro-Photonics, Swinburne University of Technology, John St., Hawthorn, 3122 Vic, Australia
| | - Akio Nitta
- Institute for Catalysis, Hokkaido University, N21, W8, 001-0021, Sapporo, Japan
| | - Maria G. Méndez-Medrano
- Laboratory of Physical Chemistry, UMR 8000, University of Paris-Saclay, 91405, Orsay, France
| | | | - Saulius Juodkazis
- Center for Micro-Photonics, Swinburne University of Technology, John St., Hawthorn, 3122 Vic, Australia
| | - Bunsho Ohtani
- Institute for Catalysis, Hokkaido University, N21, W8, 001-0021, Sapporo, Japan
| | - Ewa Kowalska
- Institute for Catalysis, Hokkaido University, N21, W8, 001-0021, Sapporo, Japan
| |
Collapse
|
4
|
Abstract
The energy crisis is one of the most serious issue that we confront today. Among different strategies to gain access to reliable fuel, the production of hydrogen fuel through the water-splitting reaction has emerged as the most viable alternative. Specifically, the studies on defect-rich TiO2 materials have been proved that it can perform as an efficient catalyst for electrocatalytic and photocatalytic water-splitting reactions. In this invited review, we have included a general and critical discussion on the background of titanium sub-oxides structure, defect chemistries and the consequent disorder arising in defect-rich Titania and their applications towards water-splitting reactions. We have particularly emphasized the origin of the catalytic activity in Titania-based material and its effects on the structural, optical and electronic behavior. This review article also summarizes studies on challenging issues on defect-rich Titania and new possible directions for the development of an efficient catalyst with improved catalytic performance.
Collapse
|
5
|
Narrow bandgap oxide nanoparticles coupled with graphene for high performance mid-infrared photodetection. Nat Commun 2018; 9:4299. [PMID: 30327474 PMCID: PMC6191432 DOI: 10.1038/s41467-018-06776-z] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 09/17/2018] [Indexed: 11/08/2022] Open
Abstract
The pursuit of optoelectronic devices operating in the mid-infrared regime is driven by both fundamental interests and envisioned applications ranging from imaging, sensing to communications. Despite continued achievements in traditional semiconductors, notorious obstacles such as the complicated growth processes and cryogenic operation preclude the usage of infrared detectors. As an alternative path towards high-performance photodetectors, hybrid semiconductor/graphene structures have been intensively explored. However, the operation bandwidth of such photodetectors has been limited to visible and near-infrared regimes. Here we demonstrate a mid-infrared hybrid photodetector enabled by coupling graphene with a narrow bandgap semiconductor, Ti2O3 (Eg = 0.09 eV), which achieves a high responsivity of 300 A W-1 in a broadband wavelength range up to 10 µm. The obtained responsivity is about two orders of magnitude higher than that of the commercial mid-infrared photodetectors. Our work opens a route towards achieving high-performance optoelectronics operating in the mid-infrared regime.
Collapse
|
6
|
Band Gap Implications on Nano-TiO₂ Surface Modification with Ascorbic Acid for Visible Light-Active Polypropylene Coated Photocatalyst. NANOMATERIALS 2018; 8:nano8080599. [PMID: 30087248 PMCID: PMC6116251 DOI: 10.3390/nano8080599] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 08/03/2018] [Accepted: 08/04/2018] [Indexed: 11/17/2022]
Abstract
The effect of surface modification using ascorbic acid as a surface modifier of nano-TiO2 heterogeneous photocatalyst was studied. The preparation of supported photocatalyst was made by a specific paste containing ascorbic acid modified TiO2 nanoparticles used to cover Polypropylene as a support material. The obtained heterogeneous photocatalyst was thoroughly characterized (scanning electron microscope (SEM), RAMAN, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and Diffuse Reflectance Spectra (DRS) and successfully applied in the visible light photodegradation of Alizarin Red S in water solutions. In particular, this new supported TiO2 photocatalyst showed a change in the adsorption mechanism of dye with respect to that of only TiO2 due to the surface properties. In addition, an improvement of photocatalytic performances in the visible light photodegration was obtained, showing a strict correlation between efficiency and energy band gap values, evidencing the favorable surface modification of TiO2 nanoparticles.
Collapse
|
7
|
Shingai D, Ide Y, Sohn WY, Katayama K. Photoexcited charge carrier dynamics of interconnected TiO2 nanoparticles: evidence of enhancement of charge separation at anatase–rutile particle interfaces. Phys Chem Chem Phys 2018; 20:3484-3489. [DOI: 10.1039/c7cp07563d] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hydrothermal treatment can improve the charge separation efficiency of P25.
Collapse
Affiliation(s)
- Daiki Shingai
- Department of Applied Chemistry
- Faculty of Science and Technology
- Chuo University
- Tokyo 112-8551
- Japan
| | - Yusuke Ide
- International Center for Materials Nanoarchitectonics (MANA) National Institute for Materials Science (NIMS)
- Ibaraki 305-0044
- Japan
| | - Woon Yong Sohn
- Department of Applied Chemistry
- Faculty of Science and Technology
- Chuo University
- Tokyo 112-8551
- Japan
| | - Kenji Katayama
- Department of Applied Chemistry
- Faculty of Science and Technology
- Chuo University
- Tokyo 112-8551
- Japan
| |
Collapse
|
8
|
Du Y, Fang J, Wang H, Yang Y. Inducible Sequential Oxidation Process in Water-Soluble Copper Nanoclusters for Direct Colorimetric Assay of Hydrogen Peroxide in a Wide Dynamic and Sampling Range. ACS APPLIED MATERIALS & INTERFACES 2017; 9:11035-11044. [PMID: 28276247 DOI: 10.1021/acsami.7b01228] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Direct and fast detection methods for H2O2 have great demand in materials science, biology, and medicine. Colorimetric assay of H2O2 has been regarded as one versatile approach that can avoid tedious operation and complicated setup. In this report, we provided a cost-effective and time-saving H2O2 colorimetric assay strategy based on a mercaptosuccinic acid (MSA)-stabilized Cu nanocluster (NC) probe without using any chromogenic reagent. Direct and fast colorimetric detection of H2O2 was realized based on the color change of MSA-capped Cu NCs in aqueous medium. It was found that the Cu NCs presented eligible resistance to natural oxidation either in concentrated solution or in the powder state. However, the dissolved oxygen in a highly diluted solution of the Cu NCs could trigger the aggregation of the Cu NCs and their further fusion into small Cu nanoparticles (NPs). When this diluted solution served as a probe solution for detecting H2O2, a sequential oxidation process occurred in the newly formed Cu NPs, including the cleavage of MSAs on the surface and conversion of Cu into Cu2O, leading to the probe with capacity for H2O2 assay in a wide dynamic and sampling range. The sensitive solution color change was attributed to the growth of the Cu NPs (fading of plasmonic absorption) upon the addition of low levels of H2O2 and the transition of the valence states of Cu (color reactions) upon the addition of high levels of H2O2. A concentration range of H2O2 from 1 μM to 1 M could be detected by a small dose of the probe. Moreover, the Cu NCs powder subsequent to storage for 10 months could maintain a similar sensitivity for H2O2 assay, which provides possibilities for a wide range of practical applications in water samples.
Collapse
Affiliation(s)
- Yibing Du
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University , Nanjing 210009, China
| | - Jun Fang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University , Nanjing 210009, China
| | - Hongli Wang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University , Nanjing 210009, China
| | - Yang Yang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University , Nanjing 210009, China
| |
Collapse
|
9
|
Chen M, Ding Y, Gao Y, Zhu X, Wang P, Shi Z, Liu Q. N,N′-di-caboxy methyl perylene diimide (PDI) functionalized CuO nanocomposites with enhanced peroxidase-like activity and their application in visual biosensing of H2O2 and glucose. RSC Adv 2017. [DOI: 10.1039/c7ra04463a] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Perylene diimide functionalized CuO nanobelts were demonstrated to possess higher intrinsic peroxidase-like activity than that of pure CuO nanobelts.
Collapse
Affiliation(s)
- Miaomiao Chen
- College of Chemical and Environmental Engineering
- Shandong University of Science and Technology
- Qingdao 266510
- P. R. China
| | - Yanan Ding
- College of Chemical and Environmental Engineering
- Shandong University of Science and Technology
- Qingdao 266510
- P. R. China
| | - Yan Gao
- College of Chemical and Environmental Engineering
- Shandong University of Science and Technology
- Qingdao 266510
- P. R. China
| | - Xixi Zhu
- College of Chemical and Environmental Engineering
- Shandong University of Science and Technology
- Qingdao 266510
- P. R. China
| | - Peng Wang
- College of Chemical and Environmental Engineering
- Shandong University of Science and Technology
- Qingdao 266510
- P. R. China
| | - Zhiqiang Shi
- School of Chemistry
- Chemical Engineering and Materials
- Shandong Normal University
- Jinan 250013
- P. R. China
| | - Qingyun Liu
- College of Chemical and Environmental Engineering
- Shandong University of Science and Technology
- Qingdao 266510
- P. R. China
| |
Collapse
|
10
|
Kumar R, Govindarajan S, Siri Kiran Janardhana RK, Rao TN, Joshi SV, Anandan S. Facile One-Step Route for the Development of in Situ Cocatalyst-Modified Ti 3+ Self-Doped TiO 2 for Improved Visible-Light Photocatalytic Activity. ACS APPLIED MATERIALS & INTERFACES 2016; 8:27642-27653. [PMID: 27667775 DOI: 10.1021/acsami.6b07000] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Development of visible-light-driven photocatalysts by employing a relatively simple, efficient, and cost-effective one-step process is essential for commercial applications. Herein, we report for the first time the synthesis of in situ Cu-ion modified Ti3+ self-doped rutile TiO2 by such a facile one-step solution precursor plasma spray (SPPS) process using a water-soluble titanium precursor. In the SPPS process, Ti3+ self-doping on Ti4+ of rutile TiO2 is found to take place because of electron transfer from the created oxygen vacancies to Ti4+-ions. In situ Cu modification of the above Ti3+ self-doped rutile TiO2 by additionally introducing a Cu solution into plasma plume is also demonstrated. While the Ti3+ self-doping induces broad absorption in the visible-light region, the addition of Cu ion leads to even broader absorption in the visible region owing to resulting synergistic properties. The above materials were evaluated for various self-cleaning photocatalytic applications under visible-light illumination. Cu-ion modified Ti3+ self-doped rutile TiO2 is noted to exhibit a remarkably enhanced visible-light activity in comparison with Ti3+ self-doped rutile TiO2, with the latter itself outperforming commercial TiO2 photocatalysts, thereby suggesting the suitability of the material for indoor applications. The broad visible-light absorption by Ti3+ self-doping, the holes with strong oxidation power generated in the valence band, and electrons in Ti3+ isolated states that are effectively separated into the high reductive sites of Cu ions upon visible-light irradiation, accounts for improved photocatalytic activity. Moreover, the synthesis process (SPPS) provides a valuable alternative to orthodox multistep processes for the preparation of such visible-light-driven photocatalysts.
Collapse
Affiliation(s)
- Raju Kumar
- Centre for Nanomaterials and ‡Centre for Engineered Coatings, International Advanced Research Centre for Powder Metallurgy and New Materials , Hyderabad 500005, India
| | - Sivakumar Govindarajan
- Centre for Nanomaterials and ‡Centre for Engineered Coatings, International Advanced Research Centre for Powder Metallurgy and New Materials , Hyderabad 500005, India
| | - Reddy Kunda Siri Kiran Janardhana
- Centre for Nanomaterials and ‡Centre for Engineered Coatings, International Advanced Research Centre for Powder Metallurgy and New Materials , Hyderabad 500005, India
| | - Tata Narasinga Rao
- Centre for Nanomaterials and ‡Centre for Engineered Coatings, International Advanced Research Centre for Powder Metallurgy and New Materials , Hyderabad 500005, India
| | - Shrikant Vishwanath Joshi
- Centre for Nanomaterials and ‡Centre for Engineered Coatings, International Advanced Research Centre for Powder Metallurgy and New Materials , Hyderabad 500005, India
| | - Srinivasan Anandan
- Centre for Nanomaterials and ‡Centre for Engineered Coatings, International Advanced Research Centre for Powder Metallurgy and New Materials , Hyderabad 500005, India
| |
Collapse
|
11
|
Qiu M, Tian Y, Chen Z, Yang Z, Li W, Wang K, Wang L, Wang K, Zhang W. Synthesis of Ti3+ self-doped TiO2 nanocrystals based on Le Chatelier's principle and their application in solar light photocatalysis. RSC Adv 2016. [DOI: 10.1039/c6ra12674j] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Ti3+-doped TiO2 nanocrystals, synthesized based on Le Chatelier's principle, show a high degradation ratio of 99% towards MB under sun light.
Collapse
Affiliation(s)
- Maoqin Qiu
- School of Chemistry and Chemical Engineering
- Hefei University of Technology
- Hefei
- China 230009
- Anhui Key Laboratory of Controllable Chemical Reaction & Material Chemical Engineering
| | - Yuan Tian
- School of Chemistry and Chemical Engineering
- Hefei University of Technology
- Hefei
- China 230009
- Anhui Key Laboratory of Controllable Chemical Reaction & Material Chemical Engineering
| | - Zhangxian Chen
- School of Chemistry and Chemical Engineering
- Hefei University of Technology
- Hefei
- China 230009
- Anhui Key Laboratory of Controllable Chemical Reaction & Material Chemical Engineering
| | - Zeheng Yang
- School of Chemistry and Chemical Engineering
- Hefei University of Technology
- Hefei
- China 230009
- Anhui Key Laboratory of Controllable Chemical Reaction & Material Chemical Engineering
| | - Wenming Li
- School of Chemistry and Chemical Engineering
- Hefei University of Technology
- Hefei
- China 230009
- Anhui Key Laboratory of Controllable Chemical Reaction & Material Chemical Engineering
| | - Kai Wang
- School of Chemistry and Chemical Engineering
- Hefei University of Technology
- Hefei
- China 230009
- Anhui Key Laboratory of Controllable Chemical Reaction & Material Chemical Engineering
| | - Lei Wang
- School of Chemistry and Chemical Engineering
- Hefei University of Technology
- Hefei
- China 230009
- Anhui Key Laboratory of Controllable Chemical Reaction & Material Chemical Engineering
| | - Kun Wang
- School of Chemistry and Chemical Engineering
- Hefei University of Technology
- Hefei
- China 230009
- Anhui Key Laboratory of Controllable Chemical Reaction & Material Chemical Engineering
| | - Weixin Zhang
- School of Chemistry and Chemical Engineering
- Hefei University of Technology
- Hefei
- China 230009
- Anhui Key Laboratory of Controllable Chemical Reaction & Material Chemical Engineering
| |
Collapse
|
12
|
Polarization induced self-doping in epitaxial Pb(Zr0.20Ti0.80)O3 thin films. Sci Rep 2015; 5:14974. [PMID: 26446442 PMCID: PMC4597211 DOI: 10.1038/srep14974] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 09/14/2015] [Indexed: 11/18/2022] Open
Abstract
The compensation of the depolarization field in ferroelectric layers requires the presence of a suitable amount of charges able to follow any variation of the ferroelectric polarization. These can be free carriers or charged defects located in the ferroelectric material or free carriers coming from the electrodes. Here we show that a self-doping phenomenon occurs in epitaxial, tetragonal ferroelectric films of Pb(Zr0.2Ti0.8)O3, consisting in generation of point defects (vacancies) acting as donors/acceptors. These are introducing free carriers that partly compensate the depolarization field occurring in the film. It is found that the concentration of the free carriers introduced by self-doping increases with decreasing the thickness of the ferroelectric layer, reaching values of the order of 1026 m−3 for 10 nm thick films. One the other hand, microscopic investigations show that, for thicknesses higher than 50 nm, the 2O/(Ti+Zr+Pb) atomic ratio increases with the thickness of the layers. These results suggest that the ratio between the oxygen and cation vacancies varies with the thickness of the layer in such a way that the net free carrier density is sufficient to efficiently compensate the depolarization field and to preserve the outward direction of the polarization.
Collapse
|
13
|
Lin Z, Li J, Zheng Z, Yan J, Liu P, Wang C, Yang G. Electronic Reconstruction of α-Ag2WO4 Nanorods for Visible-Light Photocatalysis. ACS NANO 2015; 9:7256-65. [PMID: 26061718 DOI: 10.1021/acsnano.5b02077] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
α-Ag2WO4 (AWO) has been studied extensively due to its H2 evolution and organic pollution degradation ability under the irradiation of UV light. However, the band gap of AWO is theoretically calculated to be 3.55 eV, resulting in its sluggish reaction to visible light. Herein, we demonstrated that, by using the electronic reconstruction of AWO nanorods upon a unique process of laser irradiation in liquid, these nanorods performed good visible-light photocatalytic organics degradation and H2 evolution. Using commercial AWO powders as the starting materials, we achieved the electronic reconstruction of AWO by a recrystallization of the starting powders upon laser irradiation in liquid and synthesized AWO nanorods. Due to the weak bond energy of AWO and the far from thermodynamic equilibrium process created by laser irradiation in liquid, abundant cluster distortions, especially [WO6] cluster distortions, are introduced into the crystal lattice, the defect density increases by a factor of 2.75, and uneven intermediate energy levels are inset into the band gap, resulting in a 0.44 eV decrease of the band gap, which modified the AWO itself by electronic reconstruction to be sensitive to visible light without the addition of others. Further, the first-principles calculation was carried out to clarify the electronic reconstruction of AWO, and the theoretical results confirmed the deduction based on the experimental measurements.
Collapse
|
14
|
Li LH, Deng ZX, Xiao JX, Yang GW. A metallic metal oxide (Ti5O9)-metal oxide (TiO2) nanocomposite as the heterojunction to enhance visible-light photocatalytic activity. NANOTECHNOLOGY 2015; 26:255705. [PMID: 26040400 DOI: 10.1088/0957-4484/26/25/255705] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Coupling titanium dioxide (TiO2) with other semiconductors is a popular method to extend the optical response range of TiO2 and improve its photon quantum efficiency, as coupled semiconductors can increase the separation rate of photoinduced charge carriers in photocatalysts. Differing from normal semiconductors, metallic oxides have no energy gap separating occupied and unoccupied levels, but they can excite electrons between bands to create a high carrier mobility to facilitate kinetic charge separation. Here, we propose the first metallic metal oxide-metal oxide (Ti5O9-TiO2) nanocomposite as a heterojunction for enhancing the visible-light photocatalytic activity of TiO2 nanoparticles and we demonstrate that this hybridized TiO2-Ti5O9 nanostructure possesses an excellent visible-light photocatalytic performance in the process of photodegrading dyes. The TiO2-Ti5O9 nanocomposites are synthesized in one step using laser ablation in liquid under ambient conditions. The as-synthesized nanocomposites show strong visible-light absorption in the range of 300-800 nm and high visible-light photocatalytic activity in the oxidation of rhodamine B. They also exhibit excellent cycling stability in the photodegrading process. A working mechanism for the metallic metal oxide-metal oxide nanocomposite in the visible-light photocatalytic process is proposed based on first-principle calculations of Ti5O9. This study suggests that metallic metal oxides can be regarded as partners for metal oxide photocatalysts in the construction of heterojunctions to improve photocatalytic activity.
Collapse
Affiliation(s)
- L H Li
- State Key Laboratory of Optoelectronic Materials and Technologies, Nanotechnology Research Center, School of Physics & Engineering, Sun Yat-sen University, Guangzhou 510275, Guangdong, People's Republic of China
| | | | | | | |
Collapse
|
15
|
James TH, Cannon C, Scott D, AlOthman Z, Apblett A, Materer NF. Titania-hydroxypropyl cellulose thin films for the detection of peroxide vapors. ACS APPLIED MATERIALS & INTERFACES 2014; 6:10205-10212. [PMID: 24848322 DOI: 10.1021/am501535g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Titania nanoparticles in a hydroxypropyl cellulose matrix produced using a sol-gel method were utilized to prepare films on polycarbonate slides and coatings on cellulose papers. The exposure of these materials to hydrogen peroxide gas leads to the development of an intense yellow color. By using an inexpensive web camera and a tungsten lamp to measure the reflected light, first-order behavior in the color change was observed when exposed to peroxide vapor of less than 50 ppm. For 50 mass percent titania nanoparticles in hydroxypropyl cellulose films on polycarbonate, the detection limit was estimated to be 90 ppm after a 1 min measurement and 1.5 ppm after a 1 h integration. The coatings on the filter paper had a 3-fold higher sensitivity compared to the films, with a detection limit of 5.4 ppm peroxide for a 1 min measurement and 0.09 ppm peroxide for a 1 h integration. The high sensitivity and rapid response of these films make them a promising material for use as a sensitive peroxide detector.
Collapse
Affiliation(s)
- Travis H James
- Department of Chemistry, Oklahoma State University , Stillwater, Oklahoma 74078-3071, United States
| | | | | | | | | | | |
Collapse
|
16
|
Su J, Zou X, Chen JS. Self-modification of titanium dioxide materials by Ti3+ and/or oxygen vacancies: new insights into defect chemistry of metal oxides. RSC Adv 2014. [DOI: 10.1039/c3ra47757f] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In this review, we highlight the recent research efforts towards understanding the defect chemistry of titanium dioxide. Particular attention is paid to the synthesis of self-modified TiO2 materials with Ti3+/oxygen vacancies and the favorable effects of these defects on the properties and applications of the obtained materials.
Collapse
Affiliation(s)
- Juan Su
- School of Chemistry and Chemical Engineering
- Shanghai Jiao Tong University
- Shanghai 200240, China
| | - Xiaoxin Zou
- State Key Lab of Inorganic Synthesis & Preparative Chemistry
- College of Chemistry
- Jilin University
- Changchun 130012, China
| | - Jie-Sheng Chen
- School of Chemistry and Chemical Engineering
- Shanghai Jiao Tong University
- Shanghai 200240, China
| |
Collapse
|