New Trends in Photocatalytic Applications with Alkaline Earth Metal Titanates

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Photocatalysis".

Deadline for manuscript submissions: closed (7 July 2023) | Viewed by 15129

Special Issue Editors


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Guest Editor
Department of Applied and Environmental Chemistry, University of Szeged, Szeged, Hungary
Interests: heterogeneous photocatalysis; semiconductor oxides; titanium dioxide; characterization; photocatalytic activity; catalyst preparation; nanomaterials; material science; environmental applications

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Guest Editor
1. Institute of Physical Metallurgy, Metal Forming and Nanotechnology, University of Miskolc, C/2-5 Building 209, H-3515 Miskolc-Egyetemvaros, Hungary
2. Department of Applied and Environmental Chemistry, University of Szeged, Szeged, Hungary
Interests: heterogeneous catalysis; photocatalytic materials; carbon nanotubes; nanocomposite materials; immobilization of biologically active units
Special Issues, Collections and Topics in MDPI journals
1. Department of Applied and Environmental Chemistry, Faculty of Natural Sciences and Informatics, Institute of Chemistry, University of Szeged, Szeged, Hungary
2. Faculty of Biology and Geology, Babeș-Bolyai University, Centre 3B, STAR-UBB, Cluj-Napoca, Romania
Interests: photocatalysis; ecotoxicology; environment–nanoparticle interaction; photochemistry
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Heterogeneous photocatalysis is a promising method to treat a wide variety of environmental pollutants. It is an extensively investigated research area; moreover, semiconductor oxides already have industrial applications. Alkaline earth metal titanates, a novel group of semiconductors, have attractive application prospects due to their unique properties, making them suitable for pollutant degradation, CO2 reduction, H2 generation, energy storage, and fuel cells, just to name a few. However, there are still many unanswered questions regarding the causal relationship between their structural and photocatalytic properties.

This Special Issue aims to collect papers concerning the design, synthesis, and characterization of alkaline earth metal titanates, as well as focus on their applicability. I am pleased to invite you to submit manuscripts for this Special Issue on “New Trends in Photocatalytic Applications with Alkaline Earth Metal Titanates” in Catalysts.

Dr. Tamás Gyulavári
Dr. Klára Hernádi
Dr. Zsolt Pap
Guest Editors

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Keywords

  • Heterogeneous photocatalysis
  • Perovskites
  • Alkaline earth metals
  • Titanates
  • Environmental applications
  • Pollutant degradation
  • Photoreduction
  • Carbon dioxide
  • Energy storage
  • Fuel cells

Published Papers (7 papers)

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Research

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15 pages, 6689 KiB  
Article
Enhanced Photocatalytic and Anticancer Activity of Zn-Doped BaTiO3 Nanoparticles Prepared through a Green Approach Using Banana Peel Extract
by Maqusood Ahamed and M. A. Majeed Khan
Catalysts 2023, 13(6), 985; https://doi.org/10.3390/catal13060985 - 8 Jun 2023
Cited by 4 | Viewed by 1685
Abstract
Perovskite barium titanate (BaTiO3) has received a lot of interest due to its extraordinary dielectric and ferroelectric properties, along with its moderate biocompatibility. Here, we investigated how Zn doping tuned the physicochemical characteristics, photocatalytic activity, and anticancer potential of BaTiO3 [...] Read more.
Perovskite barium titanate (BaTiO3) has received a lot of interest due to its extraordinary dielectric and ferroelectric properties, along with its moderate biocompatibility. Here, we investigated how Zn doping tuned the physicochemical characteristics, photocatalytic activity, and anticancer potential of BaTiO3 nanoparticles synthesized from banana peel extract. XRD, TEM, SEM, EDS, XPS, BET, Raman, and PL were utilized to characterize the as-synthesized pure and Zn (1 and 3 mol%)-doped BaTiO3 nanoparticles. All of the synthesized samples showed evidence of the BaTiO3 tetragonal phase, and the XRD patterns of the Zn-doped BaTiO3 nanoparticles showed the presence of a Zn peak. The particle size of BaTiO3 decreased with increasing levels of Zn doping without morphological changes. After Zn doping, the PL intensity of BaTiO3 decreased, suggesting a lower electron–hole recombination rate. BET analysis found that the surface area of Zn-doped BaTiO3 nanoparticles was higher than that of pure BaTiO3. Under visible irradiation, the photocatalytic activity of pure and Zn-doped BaTiO3 nanoparticles was compared, and a remarkable 85% photocatalytic activity of Zn (3%)-doped BaTiO3 nanoparticles was measured. As a result, Zn-doped BaTiO3 nanoparticles are recognized as excellent photocatalysts for degrading organic pollutants. According to cytotoxicity data, Zn (3%)-doped BaTiO3 nanoparticles display four-fold greater anticancer activity against human lung carcinoma (A549) than pure BaTiO3 nanoparticles. It was also observed that Zn-doped BaTiO3 nanoparticles kill cancer cells by increasing the intracellular level of reactive oxygen species. Furthermore, compared to pure BaTiO3, the Zn-doped BaTiO3 nanostructure showed better cytocompatibility in non-cancerous human lung fibroblasts (IMR90). The Zn-doped BaTiO3 nanoparticles have a reduced particle size, increased surface area, and a lower electron–hole recombination rate, which are highly beneficial for enhanced photocatalytic and anticancer activity. Overall, current data showed that green-fabricated Zn-BaTiO3 nanoparticles have superior photocatalytic and anticancer effects along with improved biocompatibility compared to those of pure BaTiO3. This work underlines the significance of utilizing agricultural waste (e.g., fruit peel) for the fabrication of BaTiO3-based nanostructures, which hold great promise for biomedical and environmental applications. Full article
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12 pages, 2657 KiB  
Article
Hydrothermal Co-Crystallization of Novel Copper Tungstate-Strontium Titanate Crystal Composite for Enhanced Photocatalytic Activity and Increased Electron–Hole Recombination Time
by Áron Ágoston and László Janovák
Catalysts 2023, 13(2), 287; https://doi.org/10.3390/catal13020287 - 27 Jan 2023
Viewed by 1443
Abstract
The development of catalysts continues to have a significant influence on science today since we can utilize them to efficiently destroy some contaminants. A study in this field is justified because there is a dearth of comprehensive literature on the creation of SrTiO [...] Read more.
The development of catalysts continues to have a significant influence on science today since we can utilize them to efficiently destroy some contaminants. A study in this field is justified because there is a dearth of comprehensive literature on the creation of SrTiO3-based photocatalysts. Related to this topic, here we report the facile preparation of a structure-modified SrTiO3 photocatalyst, by incorporating CuWO4. Within the case of the CuWO4-modified samples (0.5–3 wt% nominal CuWO4 content), the photo-oxidation of phenol, as a contaminant, was more than two times higher than the initial SrTiO3. However, the photocatalytic activity does not change linearly with increasing CuWO4 content, and the CWS2.5 (2.5 wt% nominal CuWO4 content and 4.25 wt% measured content) has the highest photo-activity under the applied conditions. The reason for the better activity was the increased recombination time of charge separation on the catalyst surface. Slower recombination can result in more water being oxidized to hydroxyl radicals, leading to the faster decomposition of the phenol. Full article
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13 pages, 5182 KiB  
Article
Influence of Rapid Heat Treatment on the Photocatalytic Activity and Stability of Strontium Titanates against a Broad Range of Pollutants
by Mahsa Abedi, Ákos Szamosvölgyi, András Sápi, Ákos Kukovecz, Zoltán Kónya, Tamás Gyulavári and Zsolt Pap
Catalysts 2023, 13(2), 219; https://doi.org/10.3390/catal13020219 - 17 Jan 2023
Cited by 3 | Viewed by 1513
Abstract
Strontium titanate (STO) photocatalysts were prepared via a slightly modified Pechini sol–gel method. A unique rapid calcination technique with a short exposure time was used to obtain crystalline products. The samples were characterized by X-ray diffractometry, scanning electron microscopy, diffuse reflectance spectroscopy, infrared [...] Read more.
Strontium titanate (STO) photocatalysts were prepared via a slightly modified Pechini sol–gel method. A unique rapid calcination technique with a short exposure time was used to obtain crystalline products. The samples were characterized by X-ray diffractometry, scanning electron microscopy, diffuse reflectance spectroscopy, infrared spectroscopy, nitrogen adsorption–desorption measurements, and X-ray photoelectron spectroscopy. Their photocatalytic activity was evaluated by the photocatalytic oxidation of phenol, oxalic acid, and chlorophenol under UV light irradiation using commercial STO as a reference. These pollutants, together with glucose and propanol, were used to investigate the stability of the samples against various functional groups. All our samples exhibited higher photocatalytic activity than the commercial STO reference. With increasing calcination temperature, the crystallinity and primary crystallite sizes increased while the band gaps and specific surface areas decreased. The photocatalytic activity of the most efficient sample was explained by the presence of SrCO3 on its surface. The STO catalysts were highly stable as they largely retained their crystalline composition after exposure to chemicals with different functional groups. Finally, we compared the costs associated with the unique calcination technique with a more conventional one and found that our method is ~35% more cost-effective. Full article
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11 pages, 3099 KiB  
Article
Optimization of Plasmonic Copper Content at Copper-Modified Strontium Titanate (Cu-SrTiO3): Synthesis, Characterization, Photocatalytic Activity
by Áron Ágoston, Ádám Balog, Šarūnas Narbutas, Imre Dékány and László Janovák
Catalysts 2022, 12(9), 1041; https://doi.org/10.3390/catal12091041 - 13 Sep 2022
Cited by 3 | Viewed by 1605
Abstract
Catalyst development still has a major impact on science today, as we can use catalysts to break down certain pollutants in an energy-efficient way. There is no comprehensive literature on the development of SrTiO3-based photocatalysts, so study in this area is [...] Read more.
Catalyst development still has a major impact on science today, as we can use catalysts to break down certain pollutants in an energy-efficient way. There is no comprehensive literature on the development of SrTiO3-based photocatalysts, so study in this area is justified. Related to this topic, here we report the facile preparation of surface-modified SrTiO3 photocatalyst, performed by plasmonic copper deposition. In the case of the copper-modified samples (0.25–3 wt.% Cu content), the photooxidation of phenol, as model contaminant, was almost 4–5 times higher than the bare SrTiO3. However, the photocatalytic activity was not linearly related to copper content, since the highest photoactivity was achieved at 1 wt.% copper content. The reason for the better activity was the plasmonic effect of copper, which increases the recombination time of charge separation on the catalyst surface. During slower recombination, more water is oxidized to hydroxyl radicals, which can lead to faster degradation of phenol. Full article
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16 pages, 4201 KiB  
Article
Role of SrCO3 on Photocatalytic Performance of SrTiO3-SrCO3 Composites
by Bíborka Boga, Norbert Steinfeldt, Nikolaos G. Moustakas, Tim Peppel, Henrik Lund, Jabor Rabeah, Zsolt Pap, Vasile-Mircea Cristea and Jennifer Strunk
Catalysts 2022, 12(9), 978; https://doi.org/10.3390/catal12090978 - 31 Aug 2022
Cited by 9 | Viewed by 2712
Abstract
Perovskites such as SrTiO3 are interesting for photocatalytic applications due to their structure-related and electronic properties. These properties are influenced by the presence of SrCO3 which is often formed simultaneously during the hydrothermal synthesis of SrTiO3. In this study, [...] Read more.
Perovskites such as SrTiO3 are interesting for photocatalytic applications due to their structure-related and electronic properties. These properties are influenced by the presence of SrCO3 which is often formed simultaneously during the hydrothermal synthesis of SrTiO3. In this study, SrTiO3-SrCO3 composites with different contents of SrCO3 (5–24 wt%) were synthesized. Their morphological, structural, and optical properties were investigated using complementary methods such as scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen sorption, and diffuse reflectance spectroscopy (DRS). Their photocatalytic activity was assessed during the degradation of diclofenac (DCFNa) in aqueous solution and CO2 photoreduction under Xe lamp irradiation. Improved photocatalytic efficiency in DCFNa degradation was observed for all the studied composites in comparison with SrTiO3, and the highest mineralization efficiency was obtained for the sample with 21 wt% SrCO3 content. The presence of SrCO3 led to an increased concentration of active species, such as OH radicals. Otherwise, its presence inhibits CH4 and C2H6 production during CO2 photoreduction compared with pure SrTiO3. Full article
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12 pages, 2297 KiB  
Article
Dependence of Photocatalytic Activity on the Morphology of Strontium Titanates
by Tamás Gyulavári, Daniella Dusnoki, Viktória Márta, Mohit Yadav, Mahsa Abedi, András Sápi, Ákos Kukovecz, Zoltán Kónya and Zsolt Pap
Catalysts 2022, 12(5), 523; https://doi.org/10.3390/catal12050523 - 7 May 2022
Cited by 8 | Viewed by 2382
Abstract
Strontium titanates were prepared with different morphologies by varying the ratio of solvents used during the synthesis. The effects of morphology and solvent (ethylene glycol to water) ratio were investigated both on the structure and photocatalytic activity of the samples. Structural properties were [...] Read more.
Strontium titanates were prepared with different morphologies by varying the ratio of solvents used during the synthesis. The effects of morphology and solvent (ethylene glycol to water) ratio were investigated both on the structure and photocatalytic activity of the samples. Structural properties were determined by X-ray diffraction, scanning electron microscopy, diffuse reflectance spectroscopy, and nitrogen adsorption measurements. The photocatalytic activity of the samples was evaluated by the photocatalytic oxidation of phenol and by the photocatalytic reduction of carbon dioxide. The ratio of solvents notably influenced the morphology, strontium carbonate content, primary crystallite size, and specific surface area of the samples. Samples prepared at low ethylene glycol to water ratios were spherical, while the ones prepared at high ethylene glycol to water ratios could be characterized predominantly by lamellar morphology. The former samples were found to have the highest efficiency for phenol degradation, while the sample with the most well-defined lamellar morphology proved to be the best for CO2 reduction. Full article
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Review

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16 pages, 2233 KiB  
Review
The Emerging Career of Strontium Titanates in Photocatalytic Applications: A Review
by Nikita Sharma and Klara Hernadi
Catalysts 2022, 12(12), 1619; https://doi.org/10.3390/catal12121619 - 9 Dec 2022
Cited by 7 | Viewed by 2083
Abstract
The growing energy demands and rapid industrialization drove the attention towards a sustainable living. The methods to a adopt renewable source of energy has made the field of heterogeneous photocatalysis so famous. The photocatalytic hydrogen production seems to be an answer for our [...] Read more.
The growing energy demands and rapid industrialization drove the attention towards a sustainable living. The methods to a adopt renewable source of energy has made the field of heterogeneous photocatalysis so famous. The photocatalytic hydrogen production seems to be an answer for our future energy crisis. In this regard, alkaline earth metal titanates with a perovskite structure are one of the in demand materials these days. Among these, strontium titanates (SrTiO3) play an important role and have shown a potential, especially in the field of hydrogen production. This review summarizes the significance of (SrTiO3) in photocatalytic water splitting, to produce hydrogen and the photocatalytic degradation of the pollutants from the waste water. Different synthesis methods used for preparing SrTiO3 are also discussed. Full article
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