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Rega R, Fioravanti A, Hejazi SMH, Shahrezaei M, Kment Š, Maddalena P, Naldoni A, Lettieri S. Charge carrier recombination processes, intragap defect states, and photoluminescence mechanisms in stoichiometric and reduced TiO 2 brookite nanorods: an interpretation scheme through in situ photoluminescence excitation spectroscopy in controlled environment. NANOSCALE 2024; 16:11296-11309. [PMID: 38787737 DOI: 10.1039/d4nr00593g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2024]
Abstract
The study of titanium dioxide (TiO2) in the brookite phase is gaining popularity as evidence has shown the efficient photocatalytic performance of this less investigated polymorph. It has been recently reported that defective anisotropic brookite TiO2 nanorods display remarkable substrate-specific reactivity towards alcohol photoreforming, with rates of hydrogen production significantly (18-fold) higher than those exhibited by anatase TiO2 nanoparticles. To elucidate the basic photo-physical mechanisms and peculiarities leading to such an improvement in the photoactive efficiency, we investigated the recombination processes of photoexcited charge carriers in both stoichiometric and reduced brookite nanorods via photoluminescence excitation spectroscopy in controlled environment. Through an investigation procedure employing both supragap and subgap excitation during successive exposure to oxidizing and reducing gaseous agents, we firstly obtained an interpretation scheme describing the main photoluminescence and charge recombination pathways in stoichiometric and reduced brookite, which includes information about the spatial and energetic position of the intragap states involved in photoluminescence mechanisms, and secondly identified a specific photoluminescence enhancement process occurring in only reduced brookite nanorods, which indicates the injection of a conduction band electron during ethanol photo-oxidation. The latter finding may shed light on the empirical evidence about the exceptional reactivity of reduced brookite nanorods toward the photo-oxidation of alcohols and the concomitant efficiency of photocatalytic hydrogen generation.
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Affiliation(s)
- Romina Rega
- Institute of Applied Sciences and Intelligent Systems "Eduardo Caianiello", National Research Council (CNR-ISASI), Via Cintia 21, 80126 Napoli, Italy
| | - Ambra Fioravanti
- Institute of Sciences and Technologies for Sustainable Energy and Mobility, National Research Council (CNR-STEMS), Via Canal Bianco 28, 44124 Ferrara, Italy
| | - S M Hossein Hejazi
- Czech Advanced Technology and Research Institute, Regional Centre of Advanced Technologies and Materials, Palacký University Olomouc, Křížkovského 511/8, 77900 Olomouc, Czech Republic
- Nanotechnology Centre, Centre for Energy and Environmental Technologies, VŠB-Technical University of Ostrava, 17. listopadu 2172/15, Poruba, 708 00 Ostrava, Czech Republic
| | - Mahdi Shahrezaei
- Czech Advanced Technology and Research Institute, Regional Centre of Advanced Technologies and Materials, Palacký University Olomouc, Křížkovského 511/8, 77900 Olomouc, Czech Republic
| | - Štěpán Kment
- Czech Advanced Technology and Research Institute, Regional Centre of Advanced Technologies and Materials, Palacký University Olomouc, Křížkovského 511/8, 77900 Olomouc, Czech Republic
- Nanotechnology Centre, Centre for Energy and Environmental Technologies, VŠB-Technical University of Ostrava, 17. listopadu 2172/15, Poruba, 708 00 Ostrava, Czech Republic
| | - Pasqualino Maddalena
- Department of Physics "E. Pancini", University of Naples Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia 21, 80126 Napoli, Italy.
| | - Alberto Naldoni
- Department of Chemistry, University of Turin, Via Pietro Giuria, 7, 10125 Torino, Italy.
| | - Stefano Lettieri
- Department of Physics "E. Pancini", University of Naples Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia 21, 80126 Napoli, Italy.
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Bayani A, Gebhardt J, Elsässer C. Electronic Bulk and Surface Properties of Titanium Dioxide Studied by DFT-1/2. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:14922-14934. [PMID: 37830187 DOI: 10.1021/acs.langmuir.3c01698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/14/2023]
Abstract
Transparent conductive oxides, such as TiO2, are important functional materials for optoelectronic and photovoltaic devices. We investigate the electronic bulk properties of the TiO2 phases rutile and anatase with the DFT-1/2 method and obtain a quantitatively good description of their electronic band structures. We then applied this method to the (001) surfaces of rutile and anatase and calculated their ionization potentials (IPs) and work functions (WF). To relate these calculated surface properties with values from experiments, we evaluated the effect of varying the oxygen stoichiometry at the surface on both IP and WF.
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Affiliation(s)
- Amirhossein Bayani
- Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstraße 11, 79108 Freiburg, Germany
| | - Julian Gebhardt
- Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstraße 11, 79108 Freiburg, Germany
- Cluster of Excellence livMatS at FIT, Freiburg Center for Interactive Materials and Bioinspired Technologies, University of Freiburg, Georges-Köhler-Allee 105, 79110 Freiburg, Germany
| | - Christian Elsässer
- Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstraße 11, 79108 Freiburg, Germany
- Cluster of Excellence livMatS at FIT, Freiburg Center for Interactive Materials and Bioinspired Technologies, University of Freiburg, Georges-Köhler-Allee 105, 79110 Freiburg, Germany
- Freiburg Materials Research Center (FMF), University of Freiburg, Stefan-Meier-Straße 21, 79104 Freiburg, Germany
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Ratthiwal J, Lazaro N, Pineda A, Esposito R, ALOthman ZA, Reubroycharoen P, Luque R. Furfural conversion over calcined Ti and Fe metal-organic frameworks under continuous flow conditions. CATAL COMMUN 2023. [DOI: 10.1016/j.catcom.2023.106649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/01/2023] Open
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Du B, Zhang M, Ye J, Wang D, Han J, Zhang T. Novel Au Nanoparticle-Modified ZnO Nanorod Arrays for Enhanced Photoluminescence-Based Optical Sensing of Oxygen. SENSORS (BASEL, SWITZERLAND) 2023; 23:s23062886. [PMID: 36991596 PMCID: PMC10051414 DOI: 10.3390/s23062886] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 03/03/2023] [Accepted: 03/03/2023] [Indexed: 05/31/2023]
Abstract
Novel optical gas-sensing materials for Au nanoparticle (NP)-modified ZnO nanorod (NR) arrays were fabricated using hydrothermal synthesis and magnetron sputtering on Si substrates. The optical performance of ZnO NR can be strongly modulated by the annealing temperature and Au sputtering time. With exposure to trace quantities of oxygen, the ultraviolet (UV) emission of the photoluminescence (PL) spectra of Au/ZnO samples at ~390 nm showed a large variation in intensity. Based on this mechanism, ZnO NR based oxygen gas sensing via PL spectra variation demonstrated a wide linear detection range of 10-100%, a high response value, and a 1% oxygen content sensitivity detection limit at 225 °C. This outstanding optical oxygen-sensing performance can be attributed to the large surface area to volume ratio, high crystal quality, and high UV emission efficiency of the Au NP-modified ZnO NR arrays. Density functional theory (DFT) simulation results confirmed that after the Au NPs modified the surface of the ZnO NR, the charge at the interface changed, and the structure of Au/ZnO had the lowest adsorption energy for oxygen molecules. These results suggest that Au NP-modified ZnO NR are promising for high-performance optical gas-sensing applications.
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Affiliation(s)
- Baosheng Du
- State Key Laboratory of Laser Propulsion and Application, Department of Aerospace Science and Technology, Space Engineering University, Beijing 101416, China
| | - Meng Zhang
- Institute of War Studies, Academy of Military Sciences, Beijing 100091, China
| | - Jifei Ye
- State Key Laboratory of Laser Propulsion and Application, Department of Aerospace Science and Technology, Space Engineering University, Beijing 101416, China
| | - Diankai Wang
- State Key Laboratory of Laser Propulsion and Application, Department of Aerospace Science and Technology, Space Engineering University, Beijing 101416, China
| | - Jianhui Han
- State Key Laboratory of Laser Propulsion and Application, Department of Aerospace Science and Technology, Space Engineering University, Beijing 101416, China
| | - Tengfei Zhang
- State Key Laboratory of Laser Propulsion and Application, Department of Aerospace Science and Technology, Space Engineering University, Beijing 101416, China
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Melnikov P, Bobrov A, Marfin Y. On the Use of Polymer-Based Composites for the Creation of Optical Sensors: A Review. Polymers (Basel) 2022; 14:polym14204448. [PMID: 36298026 PMCID: PMC9611646 DOI: 10.3390/polym14204448] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 10/08/2022] [Accepted: 10/17/2022] [Indexed: 11/16/2022] Open
Abstract
Polymers are widely used in many areas, but often their individual properties are not sufficient for use in certain applications. One of the solutions is the creation of polymer-based composites and nanocomposites. In such materials, in order to improve their properties, nanoscale particles (at least in one dimension) are dispersed in the polymer matrix. These properties include increased mechanical strength and durability, the ability to create a developed inner surface, adjustable thermal and electrical conductivity, and many others. The materials created can have a wide range of applications, such as biomimetic materials and technologies, smart materials, renewable energy sources, packaging, etc. This article reviews the usage of composites as a matrix for the optical sensors and biosensors. It highlights several methods that have been used to enhance performance and properties by optimizing the filler. It shows the main methods of combining indicator dyes with the material of the sensor matrix. Furthermore, the role of co-fillers or a hybrid filler in a polymer composite system is discussed, revealing the great potential and prospect of such matrixes in the field of fine properties tuning for advanced applications.
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Affiliation(s)
- Pavel Melnikov
- M. V. Lomonosov Institute of Fine Chemical Technologies, MIREA—Russian Technological University, 119571 Moscow, Russia
- Correspondence:
| | - Alexander Bobrov
- Department of Inorganic Chemistry, Ivanovo State University of Chemistry and Technology, Sheremetevsky pr., 10, 153010 Ivanovo, Russia
| | - Yuriy Marfin
- Department of Inorganic Chemistry, Ivanovo State University of Chemistry and Technology, Sheremetevsky pr., 10, 153010 Ivanovo, Russia
- Pacific National University, 136 Tikhookeanskaya Street, 680035 Khabarovsk, Russia
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Materials for Chemical Sensing: A Comprehensive Review on the Recent Advances and Outlook Using Ionic Liquids, Metal–Organic Frameworks (MOFs), and MOF-Based Composites. CHEMOSENSORS 2022. [DOI: 10.3390/chemosensors10080290] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The ability to measure and monitor the concentration of specific chemical and/or gaseous species (i.e., “analytes”) is the main requirement in many fields, including industrial processes, medical applications, and workplace safety management. As a consequence, several kinds of sensors have been developed in the modern era according to some practical guidelines that regard the characteristics of the active (sensing) materials on which the sensor devices are based. These characteristics include the cost-effectiveness of the materials’ manufacturing, the sensitivity to analytes, the material stability, and the possibility of exploiting them for low-cost and portable devices. Consequently, many gas sensors employ well-defined transduction methods, the most popular being the oxidation (or reduction) of the analyte in an electrochemical reactor, optical techniques, and chemiresistive responses to gas adsorption. In recent years, many of the efforts devoted to improving these methods have been directed towards the use of certain classes of specific materials. In particular, ionic liquids have been employed as electrolytes of exceptional properties for the preparation of amperometric gas sensors, while metal–organic frameworks (MOFs) are used as highly porous and reactive materials which can be employed, in pure form or as a component of MOF-based functional composites, as active materials of chemiresistive or optical sensors. Here, we report on the most recent developments relative to the use of these classes of materials in chemical sensing. We discuss the main features of these materials and the reasons why they are considered interesting in the field of chemical sensors. Subsequently, we review some of the technological and scientific results published in the span of the last six years that we consider among the most interesting and useful ones for expanding the awareness on future trends in chemical sensing. Finally, we discuss the prospects for the use of these materials and the factors involved in their possible use for new generations of sensor devices.
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Abstract
Glycerol is the main by-product of biodiesel production; its upgrading to more valuable products is a demanding issue. Hydrogenolysis to 1,2-propanediol is one of the most interesting processes among the possible upgrading routes. In this study, we propose novel copper/zirconia catalysts prepared by advanced preparation methods, including copper deposition via metal–organic framework (MOF) and support preparation via the sol–gel route. The catalysts were characterized by N2 physisorption, X-ray diffraction, Scanning Electron Microscopy, H2-TPR and NH3-TPD analyses and tested in a commercial batch reactor. The catalyst prepared by copper deposition via MOF decomposition onto commercial zirconia showed the best catalytic performance, reaching 75% yield. The improved catalytic performance was assigned to a proper combination of redox and acid properties. In particular, a non-negligible fraction of cuprous oxide and of weak acid sites seems fundamental to preferentially activate the selective pathway. In particular, these features avoid the overhydrogenolysis of 1,2-propanediol to 1-propanol and enhance glycerol dehydration to hydroxyacetone and the successive hydrogenation of hydroxyacetone to 1,2-propanediol.
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