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Huang J, Wang J, Duan H, Dong L, Chen S, Zhang J, Zhang X. Zr modulated N doping composites for CO 2 conversion into carbonates. iScience 2024; 27:109714. [PMID: 38706851 PMCID: PMC11067376 DOI: 10.1016/j.isci.2024.109714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 01/16/2024] [Accepted: 04/07/2024] [Indexed: 05/07/2024] Open
Abstract
Acidic and basic sites of catalysts are essential for CO2 capture and activation. In this work, Zr, N-ZnO/ZnAl-LDH-IL composites in ionic liquid and methanol systems were fabricated, and applied to catalyze the synthesis of ethylene carbonate (EC) from ethylene glycol (EG) and CO2 with about 4.76 mmolEC gCat.-1 h-1. The composites showed more strong basic sites due to the effective induction of reactive groups on the catalyst surface by Zr doping, resulting in an increase of pyridinic-N groups from 5.48% to 22.25%. More C atoms adjacent to pyridinic-N as strong basic sites was conducive to the activation of CO2 and EG. In addition, the possible catalytic pathway and mechanism of the composites for synthesizing EC as well as the doping of La, Fe, Ce, and Cu were also investigated, which provides an effective strategy for regulating the acid-base centers on the catalyst surface through ionic liquids and methanol solvents.
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Affiliation(s)
- Jielin Huang
- School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Mesoscience and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Jie Wang
- School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Mesoscience and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Haonan Duan
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Mesoscience and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Li Dong
- School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Mesoscience and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
- Advanced Energy Science and Technology Guangdong Laboratory, Huizhou, Guangdong 516003, China
| | - Songsong Chen
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Mesoscience and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Junping Zhang
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Mesoscience and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
- Advanced Energy Science and Technology Guangdong Laboratory, Huizhou, Guangdong 516003, China
| | - Xiangping Zhang
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Mesoscience and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
- Advanced Energy Science and Technology Guangdong Laboratory, Huizhou, Guangdong 516003, China
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Teplonogova MA, Kozlova AA, Yapryntsev AD, Baranchikov AE, Ivanov VK. Synthesis and Thermal Decomposition of High-Entropy Layered Rare Earth Hydroxychlorides. Molecules 2024; 29:1634. [PMID: 38611913 PMCID: PMC11013826 DOI: 10.3390/molecules29071634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 04/02/2024] [Accepted: 04/03/2024] [Indexed: 04/14/2024] Open
Abstract
The synthesis of multicomponent and high-entropy compounds has become a rapidly developing field in advanced inorganic chemistry, making it possible to combine the properties of multiple elements in a single phase. This paper reports on the synthesis of a series of novel high-entropy layered rare earth hydroxychlorides, namely, (Sm,Eu,Gd,Y,Er)2(OH)5Cl, (Eu,Gd,Tb,Y,Er)2(OH)5Cl, (Eu,Gd,Dy,Y,Er)2(OH)5Cl, and (Eu,Gd,Y,Er,Yb)2(OH)5Cl, using a homogeneous hydrolysis technique under hydrothermal conditions. Elemental mapping proved the even distribution of rare earth elements, while luminescence spectroscopy confirmed efficient energy transfer between europium and other rare earth cations, thus providing additional evidence of the homogeneous distribution of rare earth elements within the crystal lattice. The average rare earth cation radii correlated linearly with the unit cell parameters (0.868 < R2 < 0.982) of the high-entropy layered rare earth hydroxychlorides. The thermal stability of the high-entropy layered rare earth hydroxychlorides was similar to that of individual hydroxychlorides and their binary solid solutions.
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Affiliation(s)
- Maria A. Teplonogova
- Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Anfisa A. Kozlova
- Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Alexey D. Yapryntsev
- Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Alexander E. Baranchikov
- Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Vladimir K. Ivanov
- Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 119991 Moscow, Russia
- Faculty of Materials Science, Lomonosov Moscow State University, 119991 Moscow, Russia
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3
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Dey G, Soliman SS, McCormick CR, Wood CH, Katzbaer RR, Schaak RE. Colloidal Nanoparticles of High Entropy Materials: Capabilities, Challenges, and Opportunities in Synthesis and Characterization. ACS NANOSCIENCE AU 2024; 4:3-20. [PMID: 38406312 PMCID: PMC10885327 DOI: 10.1021/acsnanoscienceau.3c00049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Revised: 10/26/2023] [Accepted: 10/26/2023] [Indexed: 02/27/2024]
Abstract
Materials referred to as "high entropy" contain a large number of elements randomly distributed on the lattice sites of a crystalline solid, such that a high configurational entropy is presumed to contribute significantly to their formation and stability. High temperatures are typically required to achieve entropy stabilization, which can make it challenging to synthesize colloidal nanoparticles of high entropy materials. Nonetheless, strategies are emerging for the synthesis of colloidal high entropy nanoparticles, which are of interest for their synergistic properties and unique catalytic functions that arise from the large number of constituent elements and their interactions. In this Perspective, we highlight the classes of materials that have been made as colloidal high entropy nanoparticles as well as insights into the synthetic methods and the pathways by which they form. We then discuss the concept of "high entropy" within the context of colloidal materials synthesized at much lower temperatures than are typically required for entropy to drive their formation. Next, we identify and address challenges and opportunities in the field of high entropy nanoparticle synthesis. We emphasize aspects of materials characterization that are especially important to consider for nanoparticles of high entropy materials, including powder X-ray diffraction and elemental mapping with scanning transmission electron microscopy, which are among the most commonly used techniques in laboratory settings. Finally, we share perspectives on emerging opportunities and future directions involving colloidal nanoparticles of high entropy materials, with an emphasis on synthesis, characterization, and fundamental knowledge that is needed for anticipated advances in key application areas.
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Affiliation(s)
- Gaurav
R. Dey
- Department
of Chemistry, Department of Chemical Engineering,
and Materials Research
Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Samuel S. Soliman
- Department
of Chemistry, Department of Chemical Engineering,
and Materials Research
Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Connor R. McCormick
- Department
of Chemistry, Department of Chemical Engineering,
and Materials Research
Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Charles H. Wood
- Department
of Chemistry, Department of Chemical Engineering,
and Materials Research
Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Rowan R. Katzbaer
- Department
of Chemistry, Department of Chemical Engineering,
and Materials Research
Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Raymond E. Schaak
- Department
of Chemistry, Department of Chemical Engineering,
and Materials Research
Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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Li F, Yoshida K, Van Chuc N, Osada M, Abe H. Understanding the role of solvents in bottom-up synthesis of multi-element hydroxides. RSC Adv 2024; 14:75-82. [PMID: 38173604 PMCID: PMC10758770 DOI: 10.1039/d3ra07344k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Accepted: 12/11/2023] [Indexed: 01/05/2024] Open
Abstract
Here we report a comparative study on the bottom-up synthesis of multi-element hydroxides composed of Mg, Al, Fe and Zn cations to understand the role of solvents. Two common solvents, water and ethylene glycol, a typical polyol, are used. The polyol-derived MgAlFeZn-OH are nanosheets with homogeneous elemental distribution, while the hydrothermal-derived MgAlFeZn-OH are mixtures of plate-like hydroxide layers and rod-like spinel oxides. The coordinating properties and the high viscosity of the ethylene glycol provide the possibility to mediate the hydrolysis rates and to control the particle growth. The high specific surface area of the polyol-derived multi-element hydroxide nanosheets (352.4 m2 g-1) guarantees them as excellent adsorbents for adsorbing anionic dyes in aqueous solution.
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Affiliation(s)
- Fei Li
- Joining and Welding Research Institute, Osaka University Osaka 5670047 Japan
| | - Kanako Yoshida
- Joining and Welding Research Institute, Osaka University Osaka 5670047 Japan
| | - Nguyen Van Chuc
- Institute of Materials Science, Vietnam Academy of Science and Technology Hanoi Vietnam
| | - Minoru Osada
- Institute of Materials and Systems for Sustainability, Nagoya University Nagoya 4648603 Japan
| | - Hiroya Abe
- Joining and Welding Research Institute, Osaka University Osaka 5670047 Japan
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Kizhepat S, Rasal AS, Chang JY, Wu HF. Development of Two-Dimensional Functional Nanomaterials for Biosensor Applications: Opportunities, Challenges, and Future Prospects. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:nano13091520. [PMID: 37177065 PMCID: PMC10180329 DOI: 10.3390/nano13091520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 04/23/2023] [Accepted: 04/27/2023] [Indexed: 05/15/2023]
Abstract
New possibilities for the development of biosensors that are ready to be implemented in the field have emerged thanks to the recent progress of functional nanomaterials and the careful engineering of nanostructures. Two-dimensional (2D) nanomaterials have exceptional physical, chemical, highly anisotropic, chemically active, and mechanical capabilities due to their ultra-thin structures. The diversity of the high surface area, layered topologies, and porosity found in 2D nanomaterials makes them amenable to being engineered with surface characteristics that make it possible for targeted identification. By integrating the distinctive features of several varieties of nanostructures and employing them as scaffolds for bimolecular assemblies, biosensing platforms with improved reliability, selectivity, and sensitivity for the identification of a plethora of analytes can be developed. In this review, we compile a number of approaches to using 2D nanomaterials for biomolecule detection. Subsequently, we summarize the advantages and disadvantages of using 2D nanomaterials in biosensing. Finally, both the opportunities and the challenges that exist within this potentially fruitful subject are discussed. This review will assist readers in understanding the synthesis of 2D nanomaterials, their alteration by enzymes and composite materials, and the implementation of 2D material-based biosensors for efficient bioanalysis and disease diagnosis.
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Affiliation(s)
- Shamsa Kizhepat
- Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, 70, Lien-Hai Road, Kaohsiung 80424, Taiwan
- Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan
| | - Akash S Rasal
- Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan
| | - Jia-Yaw Chang
- Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan
| | - Hui-Fen Wu
- Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, 70, Lien-Hai Road, Kaohsiung 80424, Taiwan
- School of Pharmacy, College of Pharmacy, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
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Li F, Kannari N, Maruyama J, Sato K, Abe H. Defective multi-element hydroxides nanosheets for rapid removal of anionic organic dyes from water and oxygen evolution reaction. JOURNAL OF HAZARDOUS MATERIALS 2023; 447:130803. [PMID: 36680901 DOI: 10.1016/j.jhazmat.2023.130803] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/27/2022] [Accepted: 01/14/2023] [Indexed: 06/17/2023]
Abstract
Water pollution by dyes is one of the biggest environmental problems. Adsorption technology has been widely used in wastewater treatment. In this work, high-entropy concept is used to design surface defective hydroxides realizing the rapid removal of dyes from water. Multi-element hydroxides (MEHs) containing three (CoMnNi, MEH-Ternary), four (CoMnNiZn, MEH-Quaternary), and five (CoMnNiZnFe, MEH-Quinary) metal elements are successfully synthesized through a polyol process. These as-synthesized MEHs are composed of nanosheets with a brucite-like structure. Along with the increase in compositional complexity (i.e., configurational entropy), the thickness of the nanosheets in these MEHs decreases, while the degree of surface defects increase. These surface defects are probably the active sites for anionic dyes adsorption, suggesting rapid adsorption kinetics with shortened diffusion path length. For MEH-Quinary in 0.2 mM Congo red (CR) and MEH-Ternary in 0.4 mM methyl orange (MO) aqueous solutions, respectively, high removal efficiency > 99.0% is achieved in the first 30 s. Their pseudo-second-order rate constants are two orders of magnitude higher than that of activated carbon and hydrotalcite. MEH-Quinary has maximum CR and MO adsorption quantity of 546.4 and 404.9 mg g-1, respectively, by Langmuir model. The MEH-Quinary is also a potential electrocatalyst for oxygen evolution reaction.
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Affiliation(s)
- Fei Li
- Joining and Welding Research Institute, Osaka University, Osaka 5670047, Japan.
| | - Naokatsu Kannari
- Division of Environmental Engineering Science, Graduate School of Science and Technology, Gunma University, Gunma 3768515, Japan
| | - Jun Maruyama
- Osaka Research Institute of Industrial Science and Technology, Osaka 5368553, Japan
| | - Kazuyoshi Sato
- Division of Environmental Engineering Science, Graduate School of Science and Technology, Gunma University, Gunma 3768515, Japan
| | - Hiroya Abe
- Joining and Welding Research Institute, Osaka University, Osaka 5670047, Japan.
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Setyawan D, Amrillah T, Abdullah CAC, Ilhami FB, Dewi DMM, Mumtazah Z, Oktafiani A, Adila FP, Putra MFH. Crafting two-dimensional materials for contrast agents, drug, and heat delivery applications through green technologies. J Drug Target 2023; 31:369-389. [PMID: 36721905 DOI: 10.1080/1061186x.2023.2175833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The development of two-dimensional (2D) materials for biomedical applications has accelerated exponentially. Contrary to their bulk counterparts, the exceptional properties of 2D materials make them highly prospective for contrast agents for bioimage, drug, and heat delivery in biomedical treatment. Nevertheless, empty space in the integration and utilisation of 2D materials in living biological systems, potential toxicity, as well as required complicated synthesis and high-cost production limit the real application of 2D materials in those advance medical treatments. On the other hand, green technology appears to be one of strategy to shed a light on the blurred employment of 2D in medical applications, thus, with the increasing reports of green technology that promote advanced technologies, here, we compile, summarise, and synthesise information on the biomedical technology of 2D materials through green technology point of view. Beginning with a fundamental understanding, of crystal structures, the working mechanism, and novel properties, this article examines the recent development of 2D materials. As well as 2D materials made from natural and biogenic resources, a recent development in green-related synthesis was also discussed. The biotechnology and biomedical-related application constraints are also discussed. The challenges, solutions, and prospects of the so-called green 2D materials are outlined.
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Affiliation(s)
- Dwi Setyawan
- Department of Nanotechnology, Faculty of Advanced Technology and Multidiscipline, Universitas Airlangga, Surabaya, Indonesia
- Department of Pharmaceutics, Faculty of Pharmacy, Universitas Airlangga, Surabaya, Indonesia
- Green Nanotechnology Laboratory Center, Faculty of Advanced Technology and Multidiscipline, Universitas Airlangga, Surabaya, Indonesia
| | - Tahta Amrillah
- Department of Nanotechnology, Faculty of Advanced Technology and Multidiscipline, Universitas Airlangga, Surabaya, Indonesia
- Green Nanotechnology Laboratory Center, Faculty of Advanced Technology and Multidiscipline, Universitas Airlangga, Surabaya, Indonesia
| | - Che Azurahanim Che Abdullah
- Department of Physics, Faculty of Science, University Putra Malaysia, Serdang, Selangor, Malaysia
- Nanomaterial Synthesis and Characterization Laboratory, Institute of Nanoscience and Nanotechnology, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - Fasih Bintang Ilhami
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, Taiwan
- Graduate Institute of Biomedical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan
| | - Diva Meisya Maulina Dewi
- Department of Nanotechnology, Faculty of Advanced Technology and Multidiscipline, Universitas Airlangga, Surabaya, Indonesia
| | - Zuhra Mumtazah
- Department of Nanotechnology, Faculty of Advanced Technology and Multidiscipline, Universitas Airlangga, Surabaya, Indonesia
| | - Agustina Oktafiani
- Department of Nanotechnology, Faculty of Advanced Technology and Multidiscipline, Universitas Airlangga, Surabaya, Indonesia
| | - Fayza Putri Adila
- Department of Nanotechnology, Faculty of Advanced Technology and Multidiscipline, Universitas Airlangga, Surabaya, Indonesia
| | - Moch Falah Hani Putra
- Department of Nanotechnology, Faculty of Advanced Technology and Multidiscipline, Universitas Airlangga, Surabaya, Indonesia
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Bui LM, Cam ST, Buryanenko IV, Semenov VG, Nazarov DV, Kazin PE, Nevedomskiy VN, Gerasimov EY, Popkov VI. An ultra-high-entropy rare earth orthoferrite (UHE REO): solution combustion synthesis, structural features and ferrimagnetic behavior. Dalton Trans 2023; 52:4779-4786. [PMID: 36930052 DOI: 10.1039/d2dt04103k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
A novel ultra-high-entropy rare earth orthoferrite (UHE REO) of Sc1/16Y1/16La1/16Ce1/16Pr1/16Nd1/16Sm1/16Eu1/16Gd1/16Tb1/16Dy1/16Ho1/16Er1/16Tm1/16Yb1/16Lu1/16FeO3 nominal composition was successfully synthesized for the first time through a simple and efficient solution combustion approach. PXRD, Raman, and 57Fe Mössbauer spectroscopy confirmed the high chemical and phase purity of the synthesized UHE REO (hereafter denoted as ΣREFeO3), which belonged to the Pnma space group, typical of the perovskite-like rare earth orthoferrites. Despite the fact that the main X-ray reflections, vibration modes, and spectral Mössbauer components unambiguously indicate the single-phase nature of the sample, the results of SEM and TEM make it possible to establish the presence of a main (about 50 nm) and a minor ultrafine (about 10 nm) fraction of ΣREFeO3 nanoparticles. The bimodal size distribution of nanoparticles was also reflected in the magnetic behavior of this substance: the presence of several sextet components in the Mössbauer spectra, the hard single-domain magnetic nature of the main fraction of 50 nm UHE REO nanoparticles, and the superparamagnetic state of the minor fraction of 10 nm UHE REO nanoparticles. Thus, the unusual features of nanostructured ΣREFeO3 can potentially be used for the creation of new generations of transformers, magnetic memory systems, magnetic screens, radio devices, etc.
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Affiliation(s)
- Long M Bui
- Department of Physical Chemistry, Saint-Petersburg State Institute of Technology (Technical University), St. Petersburg 190013, Russia.
| | - Son T Cam
- Institute of Fundamental and Applied Sciences, Duy Tan University, Ho Chi Minh 700000, Viet Nam.,Faculty of Environmental and Chemical Engineering, Duy Tan University, Da Nang 550000, Viet Nam
| | - Ivan V Buryanenko
- Peter the Great St. Petersburg Polytechnic University, St. Petersburg 195251, Russia
| | | | - Denis V Nazarov
- Peter the Great St. Petersburg Polytechnic University, St. Petersburg 195251, Russia.,Saint Petersburg State University, St. Petersburg 199034, Russia
| | - Pavel E Kazin
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
| | | | - Evgeny Y Gerasimov
- Federal Research Center, Boreskov Institute of Catalysis SB RAS, Lavrentieva Ave. 5, 630090 Novosibirsk, Russia
| | - Vadim I Popkov
- Hydrogen Energy Laboratory, Ioffe Institute, St. Petersburg 194021, Russia
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9
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Hashishin T, Taniguchi H, Li F, Abe H. Useful High-Entropy Source on Spinel Oxides for Gas Detection. SENSORS (BASEL, SWITZERLAND) 2022; 22:4233. [PMID: 35684854 PMCID: PMC9185461 DOI: 10.3390/s22114233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 05/27/2022] [Accepted: 05/31/2022] [Indexed: 06/15/2023]
Abstract
This study aimed to identify a useful high-entropy source for gas detection by spinel oxides that are composed of five cations in nearly equal molar amounts and free of impurities. The sensor responses of the spinel oxides [1# (CoCrFeMnNi)3O4, 2# (CoCrFeMnZn)3O4, 3# (CoCrFeNiZn)3O4, 4# (CoCrMnNiZn)3O4, 5# (CoFeMnNiZn)3O4, and 6# (CrFeMnNiZn)3O4] were evaluated for the test gases (7 ppm NO2, 5000 ppm H2, 3 ppm NH3, and 3 ppm H2S). In response to NO2, 1# and 2# showed p-type behavior while 3-6# showed n-type semiconductor behavior. There are three p-type and one n-type AO structural compositions in AB2O4[AO·B2O3] type spinel, and 1# showed a stable AO composition because cation migration from site B to site A is unlikely. Therefore, it was assumed that 1# exhibited p-type behavior. The p-type behavior of 2# was influenced by Cr oxide ions that were present at the B site and the stable p-type behavior of zinc oxide at the A site. The spinel oxides 3# to 6# exhibited n-type behavior with the other cationic oxides rather than the dominant p-type behavior exhibited by the Zn oxide ions that are stable at the A site. In contrast, the sensor response to the reducing gases H2, NH3, and H2S showed p-type semiconductor behavior, with a particularly selective response to H2S. The sensor responses of the five-element spinel oxides in this study tended to be higher than that of the two-element Ni ferrites and three-element Ni-Zn ferrites reported previously. Additionally, the susceptibility to sulfurization was evaluated using the thermodynamic equilibrium theory for the AO and B2O3 compositions. The oxides of Cr, Fe, and Mn ions in the B2O3 composition did not respond to H2S because they were not sulfurized. The increase in the sensor response due to sulfurization was attributed to the decrease in the depletion layer owing to electron sensitization, as the top surface of the p-type semiconductors, ZnO and NiO, transformed to n-type semiconductors, ZnS and NiS, respectively. High-entropy oxides prepared using the hydrothermal method with an equimolar combination of five cations from six elements (Cr, Mn, Fe, Co, Ni, and Zn) can be used as a guideline for the design of high-sensitivity spinel-type composite oxide gas sensors.
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Affiliation(s)
- Takeshi Hashishin
- Faculty of Advanced Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan
- Faculty of Engineering, Kumamoto University, Kumamoto 860-8555, Japan;
| | - Haruka Taniguchi
- Faculty of Engineering, Kumamoto University, Kumamoto 860-8555, Japan;
| | - Fei Li
- Joining and Welding Research Institute, Osaka University, Osaka 567-0047, Japan;
| | - Hiroya Abe
- Joining and Welding Research Institute, Osaka University, Osaka 567-0047, Japan;
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