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P V, Liu X, Ramesh Babu R, Sathiya M, Salem Alsaiari N, Mohammed Alzahrani F, Tariq Nazir M, Elamurugu E, Zhang F. Chemically sprayed CdO: Cr thin films for formaldehyde gas detection and optoelectronic applications. CHEMOSPHERE 2023; 329:138535. [PMID: 37011820 DOI: 10.1016/j.chemosphere.2023.138535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 01/30/2023] [Accepted: 03/26/2023] [Indexed: 05/03/2023]
Abstract
Chromium (Cr) doped CdO films are chemically sprayed and are characterized by their optical, electrical, structural, and microstructural characteristics. The thickness of the films is determined by spectroscopic ellipsometry. The cubic crystal structure with a superior growth along (111) plane of the spray-deposited films is confirmed from the powder X-ray diffraction (XRD) analysis. XRD studies also suggested that some of the Cd2+ ions were substituted by Cr3+ ions, and the solubility of Cr in CdO is minimal, to be around ∼0.75 wt%. The analysis by atomic force microscopy shows uniform distribution of grains throughout the surface, whose roughness is varied from 33 to 13.9 nm concerning Cr-doping concentration. The microstructures from the field emission scanning electron microscope reveal a smooth surface. The elemental composition is examined using an energy dispersive spectroscope. The micro-Raman studies carried out in room temperature endorse the presence of metal oxide (Cd-O) bond vibrations. Transmittance spectra are obtained using UV-vis-NIR spectrophotometer, and the band gap values are estimated from the absorption coefficient. The films show high optical transmittance (>75%) in vis-NIR region. A maximum optical band gap of 2.35 eV is obtained from 1.0 wt% Cr-doping. The electrical measurement (Hall analysis) confirmed the degeneracy nature and n-type semi-conductivity. The carrier density, carrier mobility, and dc-conductivity are increased for higher Cr-dopant percentage. High mobility (85 cm2V-1s-1) is observed for 0.75 wt% Cr-doping. The 0.75 wt% Cr-doping show a remarkable response to formaldehyde gas (74.39%).
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Affiliation(s)
- Velusamy P
- School of Physics and Electronic Information, Yan'an University, Yan'an, 716000, China; Department of Physics, Thiagarajar College of Engineering, Thiruparankundram, Madurai, Tamil Nadu, 625015, India
| | - Xinghui Liu
- School of Physics and Electronic Information, Yan'an University, Yan'an, 716000, China; Department of Materials Physics, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences (SIMTS), Thandalam, Chennai, 602105, Tamilnadu, India.
| | - R Ramesh Babu
- Crystal Growth and Thin Films Laboratory, Department of Physics, Bharathidasan University, Tiruchirappalli, 620024, Tamil Nadu, India.
| | - M Sathiya
- Department of Chemistry, Thiagarajar College, Madurai Kamaraj University, Madurai, 625009, Tamil Nadu, India
| | - Norah Salem Alsaiari
- Department of Chemistry, College of Science, Princess Nourah bint Abdulrahman University, P. O. Box 84428, Riyadh, 11671, Saudi Arabia
| | - Fatimah Mohammed Alzahrani
- Department of Chemistry, College of Science, Princess Nourah bint Abdulrahman University, P. O. Box 84428, Riyadh, 11671, Saudi Arabia
| | - M Tariq Nazir
- School of Manufacturing Engineering, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Elangovan Elamurugu
- IDARE Laboratory, Department of Physics and Nanotechnology, College of Engineering and Technology, SRM Institute of Science and Technology, Kattankulathur, 603 203, Tamilnadu, India
| | - Fuchun Zhang
- School of Physics and Electronic Information, Yan'an University, Yan'an, 716000, China.
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2
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Mukherjee S, Katea SN, Rodrigues EM, Segre CU, Hemmer E, Broqvist P, Rensmo H, Westin G. Entrapped Molecule-Like Europium-Oxide Clusters in Zinc Oxide with Nearly Unaffected Host Structure. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2203331. [PMID: 36403214 DOI: 10.1002/smll.202203331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Revised: 10/14/2022] [Indexed: 06/16/2023]
Abstract
Nanocrystalline ZnO sponges doped with 5 mol% EuO1.5 are obtained by heating metal-salt complex based precursor pastes at 200-900 °C for 3 min. X-ray diffraction, transmission electron microscopy, and extended X-ray absorption fine structure (EXAFS) show that phase separation into ZnO:Eu and c-Eu2 O3 takes place upon heating at 700 °C or higher. The unit cell of the clean oxide made at 600 °C shows only ≈0.4% volume increase versus undoped ZnO, and EXAFS shows a ZnO local structure that is little affected by the Eu-doping and an average Eu3+ ion coordination number of ≈5.2. Comparisons of 23 density functional theory-generated structures having differently sized Eu-oxide clusters embedded in ZnO identify three structures with four or eight Eu atoms as the most energetically favorable. These clusters exhibit the smallest volume increase compared to undoped ZnO and Eu coordination numbers of 5.2-5.5, all in excellent agreement with experimental data. ZnO defect states are crucial for efficient Eu3+ excitation, while c-Eu2 O3 phase separation results in loss of the characteristic Eu3+ photoluminescence. The formation of molecule-like Eu-oxide clusters, entrapped in ZnO, proposed here, may help in understanding the nature of the unexpected high doping levels of lanthanide ions in ZnO that occur virtually without significant change in ZnO unit cell dimensions.
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Affiliation(s)
- Soham Mukherjee
- Department of Physics and Astronomy, Ångström Laboratory, Uppsala University, Uppsala, 75237, Sweden
| | - Sarmad Naim Katea
- Department of Chemistry-Ångström, Ångström Laboratory, Uppsala University, Uppsala, 75121, Sweden
| | - Emille M Rodrigues
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Carlo U Segre
- Center for Synchrotron Radiation Research and Instrumentation and Department of Physics, Illinois Institute of Technology, Chicago, IL, 60616, USA
| | - Eva Hemmer
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Peter Broqvist
- Department of Chemistry-Ångström, Ångström Laboratory, Uppsala University, Uppsala, 75121, Sweden
| | - Håkan Rensmo
- Department of Physics and Astronomy, Ångström Laboratory, Uppsala University, Uppsala, 75237, Sweden
| | - Gunnar Westin
- Department of Chemistry-Ångström, Ångström Laboratory, Uppsala University, Uppsala, 75121, Sweden
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3
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Zhang L, Heng CL, Wang X, Su WY, Finstad TG. Synergistically enhanced ultraviolet emission of Yb doped ZnO films by using a capping of ultrathin Al and SiO 2 microspheres. OPTICS EXPRESS 2022; 30:38167-38177. [PMID: 36258385 DOI: 10.1364/oe.472497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 09/17/2022] [Indexed: 06/16/2023]
Abstract
We studied the enhancement effects of ultraviolet (UV) emission from rare earth ytterbium (Yb) doped ZnO films, by using capping layers of Al and SiO2 micro-spheres. The films were deposited on Si substrates with magnetron sputtering followed by high temperature (∼1000°C) heat treatment, and then capped with a nanoscale ultrathin aluminum (Al) layer and/or SiO2 micro-spheres on the surface of the films. The photoluminescence (PL) results indicate that compared to the case without any capping, the UV emission is enhanced by a factor ranging from several to dozens times, the films capped with 2.0 nm Al layer and 5.0 µm SiO2 microspheres have the longest highest PL intensity among the samples. The PL enhancements are discussed in terms of increased optical (or electrical) fields around the surface of the films combined with defect passivation after the capping. Our work has proposed a strategy to enhance the UV emissions of ZnO, which will broaden the application potential of ZnO in UV photonics.
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Natesan M, Subramaniyan P, Chen TW, Chen SM, Ajmal Ali M, Al-Zaqri N. Ceria-doped zinc oxide nanorods assembled into microflower architectures as electrocatalysts for sensing of piroxicam in urine sample. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.128697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Abstract
AbstractWe report a density functional theory study of ZnO cluster doped with Eu and Mg along with native point defects using the generalized gradient approximation including the Hubbard parameter. The Zn atomic positions are found to be energetically more favorable doping sites than O. The Eu has a lower formation energy than Zn and O vacancies, helps in lowering the formation energy of point defects and induces spin polarization. Mg is less favorable dopant energetically and is not inducing any magnetism in the cluster. Presence of Eu and point defects along with Mg can help in sustaining spin polarization, implying that transition metal and rare earth dopant is a favorable combination to invoke desirable properties in ZnO based materials. Eu–Eu doping pair prefers ferromagnetic orientation and a spin flip is induced by Eu in the Eu–Mg configuration. Further, Eu doping increases the value of static refractive index and optical absorption in the UV region compared to the undoped ZnO cluster.
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Marin R, Jaque D. Doping Lanthanide Ions in Colloidal Semiconductor Nanocrystals for Brighter Photoluminescence. Chem Rev 2020; 121:1425-1462. [DOI: 10.1021/acs.chemrev.0c00692] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Riccardo Marin
- Fluorescence Imaging Group (FIG), Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, C/Francisco Tomás y Valiente 7, Madrid 28049, Spain
| | - Daniel Jaque
- Fluorescence Imaging Group (FIG), Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, C/Francisco Tomás y Valiente 7, Madrid 28049, Spain
- Nanobiology Group, Instituto Ramón y Cajal de Investigación, Sanitaria Hospital Ramón y Cajal, Ctra. De Colmenar Viejo, Km. 9100, 28034 Madrid, Spain
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Lupan C, Khaledialidusti R, Mishra AK, Postica V, Terasa MI, Magariu N, Pauporté T, Viana B, Drewes J, Vahl A, Faupel F, Adelung R. Pd-Functionalized ZnO:Eu Columnar Films for Room-Temperature Hydrogen Gas Sensing: A Combined Experimental and Computational Approach. ACS APPLIED MATERIALS & INTERFACES 2020; 12:24951-24964. [PMID: 32367706 DOI: 10.1021/acsami.0c02103] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Reducing the operating temperature to room temperature is a serious obstacle on long-life sensitivity with long-term stability performances of gas sensors based on semiconducting oxides, and this should be overcome by new nanotechnological approaches. In this work, we report the structural, morphological, chemical, optical, and gas detection characteristics of Eu-doped ZnO (ZnO:Eu) columnar films as a function of Eu content. The scanning electron microscopy (SEM) investigations showed that columnar films, grown via synthesis from a chemical solutions (SCS) approach, are composed of densely packed columnar type grains. The sample sets with contents of ∼0.05, 0.1, 0.15, and 0.2 at% Eu in ZnO:Eu columnar films were studied. Surface functionalization was achieved using PdCl2 aqueous solution with additional thermal annealing in air at 650 °C. The temperature-dependent gas-detection characteristics of Pd-functionalized ZnO:Eu columnar films were measured in detail, showing a good selectivity toward H2 gas at operating OPT temperatures of 200-300 °C among several test gases and volatile organic compound vapors, such as methane, ammonia, acetone, ethanol, n-butanol, and 2-propanol. At an operating temperature OPT of 250 °C, a high gas response Igas/Iair of ∼115 for 100 ppm H2 was obtained. Experimental results indicate that Eu doping with an optimal content of about 0.05-0.1 at% along with Pd functionalization of ZnO columns leads to a reduction of the operating temperature of the H2 gas sensor. DFT-based computations provide mechanistic insights into the gas-sensing mechanism by investigating interactions between the Pd-functionalized ZnO:Eu surface and H2 gas molecules supporting the experimentally observed results. The proposed columnar materials and gas sensor structures would provide a special advantage in the fields of fundamental research, applied physics studies, and ecological and industrial applications.
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Affiliation(s)
- Cristian Lupan
- Center for Nanotechnology and Nanosensors, Department of Microelectronics and Biomedical Engineering, Technical University of Moldova, 168, Stefan cel Mare Av., MD-2004 Chisinau, Republic of Moldova
| | - Rasoul Khaledialidusti
- Department of Mechanical and Industrial Engineering, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway
| | - Abhishek Kumar Mishra
- Department of Physics, School of Engineering, University of Petroleum & Energy Studies, Bidholi via Premnagar, Dehradun 248007, India
| | - Vasile Postica
- Center for Nanotechnology and Nanosensors, Department of Microelectronics and Biomedical Engineering, Technical University of Moldova, 168, Stefan cel Mare Av., MD-2004 Chisinau, Republic of Moldova
| | - Maik-Ivo Terasa
- Functional Nanomaterials, Faculty of Engineering, Institute for Materials Science, Kiel University, Kaiserstr. 2, D-24143 Kiel, Germany
| | - Nicolae Magariu
- Center for Nanotechnology and Nanosensors, Department of Microelectronics and Biomedical Engineering, Technical University of Moldova, 168, Stefan cel Mare Av., MD-2004 Chisinau, Republic of Moldova
| | - Thierry Pauporté
- PSL Université, Chimie ParisTech, CNRS, Institut de Recherche de Chimie Paris (IRCP), 11 rue P. et M. Curie, F, 75005 Paris, France
| | - Bruno Viana
- PSL Université, Chimie ParisTech, CNRS, Institut de Recherche de Chimie Paris (IRCP), 11 rue P. et M. Curie, F, 75005 Paris, France
| | - Jonas Drewes
- Chair for Multicomponent Materials, Faculty of Engineering, Institute for Materials Science, Kiel University, Kaiserstr. 2, D-24143 Kiel, Germany
| | - Alexander Vahl
- Chair for Multicomponent Materials, Faculty of Engineering, Institute for Materials Science, Kiel University, Kaiserstr. 2, D-24143 Kiel, Germany
| | - Franz Faupel
- Chair for Multicomponent Materials, Faculty of Engineering, Institute for Materials Science, Kiel University, Kaiserstr. 2, D-24143 Kiel, Germany
| | - Rainer Adelung
- Functional Nanomaterials, Faculty of Engineering, Institute for Materials Science, Kiel University, Kaiserstr. 2, D-24143 Kiel, Germany
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Katea SN, Broqvist P, Kullgren J, Hemmer E, Westin G. Fast, Low-Cost Synthesis of ZnO:Eu Nanosponges and the Nature of Ln Doping in ZnO. Inorg Chem 2020; 59:7584-7602. [PMID: 32374596 DOI: 10.1021/acs.inorgchem.0c00472] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A low-cost template-free solution chemical route to highly porous nanocrystalline sponges of ZnO-EuO1.5 with 0-5 mol % Eu is presented. The process uses Zn- and Eu-acetate-nitrate and triethanolamine as precursors in methanol. After evaporation of the solvent and heating at 200 °C for 3 min, crystalline ZnO:Eu sponges with minor amounts of organic residues were obtained. Heating to 400 °C replaced the organics with carbonate, which in its turn was decomposed at temperatures below 600 °C, forming ZnO:Eu sponges. Samples heated to 200-1000 °C for 3 min were studied with XRD, SEM, TEM, TG, XPS, and IR spectroscopy. The ZnO:Eu crystallite sizes could be tuned from below 10 nm for sponges prepared at 200-500 °C, to over 100 nm range at 900 °C, without sintering of the overall microstructure. XRD showed the presence of hexagonal ZnO:Eu (or at 700-1000 °C, ZnO:Eu and cubic Eu2O3) as the only phases present. The ZnO:Eu had slightly larger unit cell dimensions than the literature value of ZnO for samples obtained at 200-600 °C, while the unit cells of samples obtained at higher temperatures were quite close to the value of undoped ZnO. XPS showed that Eu was mainly in its 3+ state and well-distributed within the sponges but segregated at the ZnO sponge surface upon heating at 700-1000 °C, in accordance with XRD studies showing Eu2O3 formation.
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Affiliation(s)
- Sarmad Naim Katea
- Department of Chemistry-Ångström, Ångström Laboratory, Uppsala University, 75121 Uppsala, Sweden
| | - Peter Broqvist
- Department of Chemistry-Ångström, Ångström Laboratory, Uppsala University, 75121 Uppsala, Sweden
| | - Jolla Kullgren
- Department of Chemistry-Ångström, Ångström Laboratory, Uppsala University, 75121 Uppsala, Sweden
| | - Eva Hemmer
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Gunnar Westin
- Department of Chemistry-Ångström, Ångström Laboratory, Uppsala University, 75121 Uppsala, Sweden
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9
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Cost-effective ZnO–Eu3+ films with efficient energy transfer between host and dopant. SN APPLIED SCIENCES 2020. [DOI: 10.1007/s42452-020-2670-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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10
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Structural, optical and photoluminescence properties of Eu doped ZnO thin films prepared by spin coating. J Mol Struct 2019. [DOI: 10.1016/j.molstruc.2019.04.128] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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11
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Ce doped ZnO/f-MWCNT moss ball like nanocomposite: a strategy for high responsive current detection of L-tryptophan. Mikrochim Acta 2018; 185:96. [DOI: 10.1007/s00604-017-2641-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 12/28/2017] [Indexed: 11/25/2022]
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12
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Chi F, Wei X, Jiang B, Chen Y, Duan C, Yin M. Luminescence properties and the thermal quenching mechanism of Mn2+ doped Zn2GeO4 long persistent phosphors. Dalton Trans 2018; 47:1303-1311. [DOI: 10.1039/c7dt03906a] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Luminescence and thermal quenching mechanisms for excitation and emission in ZGO:2% Mn2+ phosphors.
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Affiliation(s)
- Fengfeng Chi
- Key Laboratory of Strongly-Coupled Quantum Matter Physics
- Chinese Academy of Sciences
- School of Physical Sciences
- University of Science and Technology of China
- Hefei
| | - Xiantao Wei
- Physics Experiment Teaching Center
- School of Physical Sciences
- University of Science and Technology of China
- Hefei 230026
- China
| | - Bin Jiang
- Key Laboratory of Strongly-Coupled Quantum Matter Physics
- Chinese Academy of Sciences
- School of Physical Sciences
- University of Science and Technology of China
- Hefei
| | - Yonghu Chen
- Key Laboratory of Strongly-Coupled Quantum Matter Physics
- Chinese Academy of Sciences
- School of Physical Sciences
- University of Science and Technology of China
- Hefei
| | - Changkui Duan
- Key Laboratory of Strongly-Coupled Quantum Matter Physics
- Chinese Academy of Sciences
- School of Physical Sciences
- University of Science and Technology of China
- Hefei
| | - Min Yin
- Key Laboratory of Strongly-Coupled Quantum Matter Physics
- Chinese Academy of Sciences
- School of Physical Sciences
- University of Science and Technology of China
- Hefei
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13
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Senapati S, Nanda KK. Designing Dual Emissions via Co-doping or Physical Mixing of Individually Doped ZnO and Their Implications in Optical Thermometry. ACS APPLIED MATERIALS & INTERFACES 2017; 9:16305-16312. [PMID: 28447787 DOI: 10.1021/acsami.7b00587] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Here, we report on the novel design of dual emission via defect state engineering in codoped oxide microstructures and its implication in fluorescence intensity ratio (FIR) based optical temperature sensing. Eu- and Er-co-doped ZnO (EuEr:ZnO) microrods prepared by hydrothermal method. The emission peaks corresponding to Eu3+ and Er3+ are observed suggesting dual emission from codoped ZnO. Interestingly, Er3+ peak intensity decreases and that of Eu3+ increases with increase of temperature as is the case of individual doped cases and dual emission is also achieved via phyical mixing of the individual doped ZnO. The opposite trend is due to the electron transfer from the defect levels of host ZnO to Eu3+ and not to Er3+. Overall, our results pave the way in designing dual emission that can be exploited in FIR based temperature sensing. As an example, we probe temperature dependency of congo-red and polyvinyle alcohol (PVA) composite using EuEr:ZnO as optical probe for temperature sensing.
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Affiliation(s)
- Subrata Senapati
- Materials Research Centre, Indian Institute of Science , Bangalore-560012, India
| | - Karuna Kar Nanda
- Materials Research Centre, Indian Institute of Science , Bangalore-560012, India
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14
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Senapati S, Kar Nanda K. Ultrahigh-sensitive optical temperature sensing based on quasi-thermalized green emissions from Er:ZnO. Phys Chem Chem Phys 2017; 19:2346-2352. [DOI: 10.1039/c6cp06608a] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Green emitting Er:ZnO microrods for ultra-high sensitive optical ratiometric temperature sensing, by following the fluorescence intensity ratio technique.
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Affiliation(s)
- Subrata Senapati
- Materials Research Centre
- Indian Institute of Science
- Bangalore-560012
- India
| | - Karuna Kar Nanda
- Materials Research Centre
- Indian Institute of Science
- Bangalore-560012
- India
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15
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Carrier dynamics and the role of surface defects: Designing a photocatalyst for gas-phase CO2 reduction. Proc Natl Acad Sci U S A 2016; 113:E8011-E8020. [PMID: 27911785 DOI: 10.1073/pnas.1609374113] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In2O3-x(OH)y nanoparticles have been shown to function as an effective gas-phase photocatalyst for the reduction of CO2 to CO via the reverse water-gas shift reaction. Their photocatalytic activity is strongly correlated to the number of oxygen vacancy and hydroxide defects present in the system. To better understand how such defects interact with photogenerated electrons and holes in these materials, we have studied the relaxation dynamics of In2O3-x(OH)y nanoparticles with varying concentration of defects using two different excitation energies corresponding to above-band-gap (318-nm) and near-band-gap (405-nm) excitations. Our results demonstrate that defects play a significant role in the excited-state, charge relaxation pathways. Higher defect concentrations result in longer excited-state lifetimes, which are attributed to improved charge separation. This correlates well with the observed trends in the photocatalytic activity. These results are further supported by density-functional theory calculations, which confirm the positions of oxygen vacancy and hydroxide defect states within the optical band gap of indium oxide. This enhanced understanding of the role these defects play in determining the optoelectronic properties and charge carrier dynamics can provide valuable insight toward the rational development of more efficient photocatalytic materials for CO2 reduction.
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16
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Wang JX, Zhuo Y, Zhou Y, Wang HJ, Yuan R, Chai YQ. Ceria Doped Zinc Oxide Nanoflowers Enhanced Luminol-Based Electrochemiluminescence Immunosensor for Amyloid-β Detection. ACS APPLIED MATERIALS & INTERFACES 2016; 8:12968-12975. [PMID: 27145690 DOI: 10.1021/acsami.6b00021] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In this work, ceria doped ZnO nanomaterials with flower-structure (Ce:ZONFs) were prepared to construct a luminol-based electrochemiluminescence (ECL) immunosensor for amyloid-β protein (Aβ) detection. Herein, carboxyl groups (-COOH) covered Ce:ZONFs were synthesized by a green method with lysine as reductant. After that, Ce:ZONFs-based ECL nanocomposite was prepared by combining the luminophore of luminol and Ce:ZONFs via amidation and physical absorption. Luminol modified on Ce:ZONFs surface could generate a strong ECL signal under the assistance of reactive oxygen species (ROSs) (such as OH(•) and O2(•-)), which were produced by a catalytic reaction between Ce:ZONFs and H2O2. It was worth noticing that a quick Ce(4+) ↔ Ce(3+) reaction in this doped material could increase the rate of electron transfer to realize the signal amplification. Subsequently, the luminol functionalized Ce:ZONFs (Ce:ZONFs-Lum) were covered by secondary antibody (Ab2) and glucose oxidase (GOD), respectively, to construct a novel Ab2 bioconjugate (Ab2-GOD@Ce:ZONFs-Lum). The wire-structured silver-cysteine complex (AgCys NWs) with a large number of -COOH, which was synthesized by AgNO3 and l-cysteine, was used as substrate of the immunosensor to capture the primary antibody (Ab1). Under the optimal conditions, this proposed ECL immunosensor had exhibited high sensitivity for Aβ detection with a wide linear range from 80 fg/mL to 100 ng/mL and an ultralow detection limit of 52 fg/mL. Meanwhile, this biosensor had good specificity for Aβ, indicating that the provided strategy had a promising potential in the detection of Aβ.
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Affiliation(s)
- Jing-Xi Wang
- Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, PR China
| | - Ying Zhuo
- Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, PR China
| | - Ying Zhou
- Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, PR China
| | - Hai-Jun Wang
- Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, PR China
| | - Ruo Yuan
- Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, PR China
| | - Ya-Qin Chai
- Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, PR China
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17
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Ghuman KK, Hoch LB, Szymanski P, Loh JYY, Kherani NP, El-Sayed MA, Ozin GA, Singh CV. Photoexcited Surface Frustrated Lewis Pairs for Heterogeneous Photocatalytic CO2 Reduction. J Am Chem Soc 2016; 138:1206-14. [DOI: 10.1021/jacs.5b10179] [Citation(s) in RCA: 160] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Kulbir Kaur Ghuman
- Department
of Materials Science and Engineering, University of Toronto, 184 College
Street, Suite 140, Toronto, Ontario M5S 3E4, Canada
| | - Laura B. Hoch
- Department
of Chemistry, University of Toronto, 80 St. George Street, Rm 326, Toronto, Ontario M5S 3E4, Canada
| | - Paul Szymanski
- Laser
Dynamics Laboratory, School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, Georgia 30332-0400, United States
| | - Joel Y. Y. Loh
- The
Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada
| | - Nazir P. Kherani
- Department
of Materials Science and Engineering, University of Toronto, 184 College
Street, Suite 140, Toronto, Ontario M5S 3E4, Canada
- The
Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada
| | - Mostafa A. El-Sayed
- Laser
Dynamics Laboratory, School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, Georgia 30332-0400, United States
| | - Geoffrey A. Ozin
- Department
of Chemistry, University of Toronto, 80 St. George Street, Rm 326, Toronto, Ontario M5S 3E4, Canada
| | - Chandra Veer Singh
- Department
of Materials Science and Engineering, University of Toronto, 184 College
Street, Suite 140, Toronto, Ontario M5S 3E4, Canada
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18
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Yao N, Huang J, Fu K, Deng X, Ding M, Shao M, Xu X. Enhanced light harvesting of dye-sensitized solar cells with up/down conversion materials. Electrochim Acta 2015. [DOI: 10.1016/j.electacta.2014.12.095] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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19
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Yu Q, Ai T, Jiang L, Zhang Y, Li C, Yuan X. Efficient energy transfer in Eu-doped ZnO on diamond film. RSC Adv 2014. [DOI: 10.1039/c4ra08739a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Eu-zinc oxide (ZnO) has been fabricated on a p-diamond substrate by a hydrothermal technique.
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Affiliation(s)
- Qi Yu
- School of Materials Science and Engineering
- Shaanxi University of Technology
- Hanzhong 723001, P. R. China
| | - Taotao Ai
- School of Materials Science and Engineering
- Shaanxi University of Technology
- Hanzhong 723001, P. R. China
| | - Liyun Jiang
- School of Physics and Telecommunication Engineering
- Shaanxi University of Technology
- Hanzhong 723001, P. R. China
| | - Yingtang Zhang
- School of Materials Science and Engineering
- Shaanxi University of Technology
- Hanzhong 723001, P. R. China
| | - Chuang Li
- School of Materials Science and Engineering
- Shaanxi University of Technology
- Hanzhong 723001, P. R. China
| | - Xinqiang Yuan
- School of Materials Science and Engineering
- Shaanxi University of Technology
- Hanzhong 723001, P. R. China
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