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Liapun V, Hanif MB, Sihor M, Vislocka X, Pandiaraj S, V K U, Thirunavukkarasu GK, Edelmannová MF, Reli M, Monfort O, Kočí K, Motola M. Versatile application of BiVO 4/TiO 2 S-scheme photocatalyst: Photocatalytic CO 2 and Cr(VI) reduction. Chemosphere 2023:139397. [PMID: 37406942 DOI: 10.1016/j.chemosphere.2023.139397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 06/20/2023] [Accepted: 06/30/2023] [Indexed: 07/07/2023]
Abstract
Herein, the synthesis, characterization, and reduction properties of 2D TiO2 aerogel powder decorated with BiVO4 (TiO2/BiVO4) were investigated for versatile applications. First, 2D TiO2 was prepared via lyophilization and subsequently modified with BiVO4 using a wet impregnation method. The morphology, structure, composition, and optical properties were evaluated using transmission electron microscopy (TEM), X-ray diffractometry (XRD), laser-induced breakdown spectroscopy (LIBS), and diffuse reflectance spectroscopy (DRS), respectively. Significantly enhanced photocurrent densities (by 3-15 times) were obtained for TiO2/BiVO4 compared to those of pure TiO2 and BiVO4. The reduction of toxic Cr(VI) to Cr(III) was assessed, including the effect of pH on overall photocatalytic efficiency. Under acidic conditions (pH ∼ 2), Cr(VI) reduction efficiency reached 100% within 2 h. For photocatalytic CO2 reduction, the highest yields of CH4 and CO were obtained using TiO2/BiVO4. A higher efficiency for both applications was achieved because of the better separation of the electron-hole pairs in TiO2/BiVO4. The excellent stability of TiO2/BiVO4 over repeated runs highlights its potential for use in versatile environmental applications. The efficiency of TiO2/BiVO4 is due to the interplay of the structure, morphology, composition, and photoelectrochemical properties that favour the material for the presented herein photocatalytic applications.
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Affiliation(s)
- Viktoriia Liapun
- Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University Bratislava, Ilkovicova 6, 842 15, Bratislava, Slovakia; Department of Environmental Ecology and Landscape Management, Faculty of Natural Sciences, Comenius University Bratislava, Ilkovicova 6, 842 15, Bratislava, Slovakia
| | - Muhammad Bilal Hanif
- Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University Bratislava, Ilkovicova 6, 842 15, Bratislava, Slovakia
| | - Marcel Sihor
- Institute of Environmental Technology, CEET, VSB-Technical University of Ostrava, 17. Listopadu 15/2172, Ostrava, Poruba, Czech Republic
| | - Xenia Vislocka
- Institute of Inorganic Chemistry, Czech Academy of Sciences, Husinec-Rez 1001, Rez, 250 68, Czech Republic
| | - Saravanan Pandiaraj
- Department of Self-Development Skills, CFY Deanship, King Saud University, Riyadh, 11451, Saudi Arabia
| | - Unnikrishnan V K
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, 576104, India
| | - Guru Karthikeyan Thirunavukkarasu
- Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University Bratislava, Ilkovicova 6, 842 15, Bratislava, Slovakia
| | - Miroslava Filip Edelmannová
- Institute of Environmental Technology, CEET, VSB-Technical University of Ostrava, 17. Listopadu 15/2172, Ostrava, Poruba, Czech Republic
| | - Martin Reli
- Institute of Environmental Technology, CEET, VSB-Technical University of Ostrava, 17. Listopadu 15/2172, Ostrava, Poruba, Czech Republic
| | - Olivier Monfort
- Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University Bratislava, Ilkovicova 6, 842 15, Bratislava, Slovakia
| | - Kamila Kočí
- Institute of Environmental Technology, CEET, VSB-Technical University of Ostrava, 17. Listopadu 15/2172, Ostrava, Poruba, Czech Republic.
| | - Martin Motola
- Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University Bratislava, Ilkovicova 6, 842 15, Bratislava, Slovakia.
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Hanif MB, Thirunavukkarasu GK, Liapun V, Makarov H, Gregor M, Roch T, Plecenik T, Hensel K, Sihor M, Monfort O, Motola M. Fluoride-free synthesis of anodic TiO 2 nanotube layers: a promising environmentally friendly method for efficient photocatalysts. Nanoscale 2022; 14:11703-11709. [PMID: 35913399 DOI: 10.1039/d2nr03379h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
TiO2 nanotube (TNT) layers are generally prepared in fluoride-based electrolytes via electrochemical anodization that relies on the field-assisted dissolution of Ti metal forming nanoporous/nanotubular structures. However, the usage of fluoride ions is considered hazardous to the environment. Therefore, we present an environmentally friendly synthesis and application of TNT layers prepared in fluoride-free nitrate-based electrolytes. A well-defined nanotubular structure with thickness up to 1.5 μm and an inner tube diameter of ∼55 nm was obtained within 5 min using aqueous X(NO3)Y electrolytes (X = Na+, K+, Sr2+, Ag+). For the first time, we show the photocatalytic performance (using a model organic pollutant), HO˙ radical production, and thorough characterization of TNT layers prepared in such electrolytes. The highest degradation efficiency (k = 0.0113 min-1) and HO˙ radical production rate were obtained using TNT layers prepared in AgNO3 (Ag-NT). The intrinsic properties of Ag-NT such as the valence band maximum of ∼2.9 eV, surface roughness of ∼6 nm, and suitable morphological features and crystal structure were obtained. These results have the potential to pave the way for a more environmentally friendly synthesis of anodic TNT layers in the future using the next generation of fluoride-free nitrate-based electrolytes.
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Affiliation(s)
- Muhammad Bilal Hanif
- Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University Bratislava, Ilkovicova 6, 842 15 Bratislava, Slovakia.
| | - Guru Karthikeyan Thirunavukkarasu
- Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University Bratislava, Ilkovicova 6, 842 15 Bratislava, Slovakia.
| | - Viktoriia Liapun
- Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University Bratislava, Ilkovicova 6, 842 15 Bratislava, Slovakia.
| | - Hryhorii Makarov
- Department of Experimental Physics, Faculty of Mathematics, Physics, and Informatics, Comenius University Bratislava, 842 48 Bratislava, Slovakia
| | - Maros Gregor
- Department of Experimental Physics, Faculty of Mathematics, Physics, and Informatics, Comenius University Bratislava, 842 48 Bratislava, Slovakia
| | - Tomas Roch
- Department of Experimental Physics, Faculty of Mathematics, Physics, and Informatics, Comenius University Bratislava, 842 48 Bratislava, Slovakia
| | - Tomas Plecenik
- Department of Experimental Physics, Faculty of Mathematics, Physics, and Informatics, Comenius University Bratislava, 842 48 Bratislava, Slovakia
| | - Karol Hensel
- Division of Environmental Physics, Faculty of Mathematics, Physics, and Informatics, Comenius University Bratislava, 842 48 Bratislava, Slovakia
| | - Marcel Sihor
- Institute of Environmental Technology, CEET, VSB-Technical University of Ostrava, 17. listopadu 15/2172, Ostrava-Poruba, Czech Republic
| | - Olivier Monfort
- Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University Bratislava, Ilkovicova 6, 842 15 Bratislava, Slovakia.
| | - Martin Motola
- Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University Bratislava, Ilkovicova 6, 842 15 Bratislava, Slovakia.
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Matĕjová L, Cieslarová M, Matĕj Z, Danis S, Peikertová P, Sihor M, Lang J, Matĕjka V. Microstructure, Optical and Photocatalytic Properties of TiO₂ Thin Films Prepared by Chelating-Agent Assisted Sol-Gel Method. J Nanosci Nanotechnol 2016; 16:504-514. [PMID: 27398480 DOI: 10.1166/jnn.2016.10684] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Single and multilayer TiO₂ thin films coated on two types of soda-lime glass substrates (microscope slides and cylinders) were prepared by a chelating agent-assisted sol-gel method, using ethyl acetoacetate as a chelating agent, dip-coating and calcination at 500 °C for 2 h in air. Phase composition, microstructural, morphological and optical properties of thin films were comprehensively investigated by using XRF, advanced XRD analysis, Raman and UV-vis spectroscopy and AFM. It was found out that the thickness of thin films increases linearly with increasing number of deposited layers, indicating a good adhesion of the titania solution to a glass substrate as well as to a previously calcined layer. 1 layer film crystallized to anatase-TiO₂(B) mixture with minor/negligible amount of nanosized brookite, 2-4 layers films crystallized to anatase-brookite-TiO₂(B) mixture. In contrast to other multilayers films, 4 layers film was highly inhomogeneous. The different phase composition of thin films was clarified based on the crystallization via titanate/s and metastable monoclinic TiO₂(B) as a consequence of several phenomena; the diffusion of Na⁺ ions from a soda-lime glass substrate, acidic conditions and repeated thermal treatment. The multilayer films were in average highly transparent (80-95%) in the visible light region with the sharp absorption edge in the UV light region. Additionally, the photocatalytic properties of selected multilayer films were compared in AO7 photodegradation. Photocatalytic experiments showed that thicker 4 layers film of tricrystalline anatase-brookite-TiO₂(B) phase mixture was similarly active as thinner 3 layers film of similar phase composition, which may be a consequence of the inhomogeneity of the thicker film.
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Sihor M, Kočí K, Matĕjová L, Reli M, Ambrožová N, Pavlovský J, Capek L, Obalová L. Photocatalytic Hydrogen Formation from Ammonia in an Aqueous Solution Over Pt-Enriched TiO2-ZrO2 Photocatalyst. J Nanosci Nanotechnol 2015; 15:6833-6839. [PMID: 26716252 DOI: 10.1166/jnn.2015.10877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The aim of this study was to remove ammonia from an aqueous solution by its decomposition to valuable products such as H2 and harmless N2 under UV light. The decomposition of ammonia by photocatalytic process represents an emerging and interesting way of its removal since beside the need of its reduction from the drinking and wastewaters with the respect to its negative impact on human and mammals health, it can lead to generation of hydrogen as an alternative fuel. A laboratory-synthesized Pt/TiO2-ZrO2 photocatalyst was studied and its photocatalytic activity was compared with the activity of commercial TiO2 Evonik P25. The Pt/TiO2-ZrO2 photocatalyst was prepared by combining a sol-gel process controlled within reverse micelles of nonionic surfactant Triton X-114 in cyclohexane, impregnation under vacuum and calcination. Explored photocatalysts were characterized by organic elementary analysis, nitrogen physisorption, XRD, FESEM and UV-Vis spectroscopy. The real platinum content in the Pt/TiO2-ZrO2 photocatalyst was determined by ICP-MS. The photocatalytic decomposition of ammonia was investigated in the time range of 0-12 h. During the first two hours the generation of hydrogen was almost negligible. The generation of hydrogen increased after 4 h of irradiation. Based on time dependences of ammonia decomposition the kinetic rate constants for Pt/TiO2-ZrO2 and TiO2 Evonik P25 photocatalysts were calculated. The ammonia photocatalytic decomposition was described well by the first order kinetic equation. The photocatalytic ammonia decomposition over the platinized TiO2-ZrO2 photocatalyst was proving 2 times higher photocatalytic performance than Evonik P25 (1241 μmol/g(cat) and 665 μmol/g(cat), respectively).
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