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Nanocatalysis for Environmental Protection, Energy, and Green Chemistry
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Nanocatalysis for Environmental Protection, Energy, and Green Chemistry

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Environmental Nanoscience and Nanotechnology".

Deadline for manuscript submissions: closed (31 March 2023) | Viewed by 18991

Special Issue Editors

Prof. Dr. Ioannis V. Yentekakis

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Guest Editor
Physical Chemistry and Chemical Processes Laboratory, School of Environmental Engineering, Technical University of Crete (TUC), 73100 Chania, Greece
Interests: nanomaterials and nanotechnology; heterogeneous nano-catalysis; environmental catalysis (NOx, N2O; CO, CH4, VOCs, H2S and SO2 emissions control); catalysts’ promotion; electrochemical promotion; surfaces and interfaces; electrochemistry; fuel cells; CO2 utilization; biogas and natural gas valorization
Special Issues, Collections and Topics in MDPI journals
Dr. Paraskevi Panagiotopoulou

E-Mail Website
Guest Editor
School of Chemical and Environmental Engineering, Technical University of Crete, 73100 Chania, Greece
Interests: heterogeneous catalysis; environmental catalysis; materials synthesis and characterization; reaction kinetics and mechanisms; catalysts for environmental and energy-related applications
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Currently, nanoscience and nanotechnology present cutting-edge areas of ​​modern science and technology across an array of applications. The design of nano-catalysts is now considered "one way" in modern heterogeneous catalysis. The rational design of nanostructured catalysts provides materials characterized by well-tailored activity/selectivity/stability in applications related to environmental protection and remediation, circular economy, sustainability, and green energy technologies, as well as green chemical production.

MDPI's journal 'Nanomaterials' has been established at the top of the list of highly regarded journals in the field to serve as a platform for innovative results and ideas to stimulate and discuss scientific research in the topics and related fields highlighted below, providing high readership and reliability.

This Special Issue, entitled “Nanocatalysis for Environmental Protection, Energy, and Green Chemistry”, aims to host significant advances in the aforementioned areas including, but not limited to, the design, synthesis, and characterization of nano-catalysts for:

  • Greenhouse gases abatement: CO2 capture, sequestration, and utilization (CO2 recycling to methane and renewable fuels, power-to-gas technology); N2O abatement; CH4
  • Clean energy topics: H2 production and cleaning of the produced gas stream (CH4, biogas and hydrocarbons reforming, water–gas shift reaction, preferential CO oxidation reaction, etc.); fuel cells.
  • Photo-electro-chemical wastewater and water treatment; photo-electro-chemical CO2 reduction; electrochemical water splitting.
  • Emission control catalysis: De-(NOx, CH4, VOCs, H2S, CO, soot).
  • Green chemical production.

This Special Issue also welcomes the submission of papers that will be presented in the "16th Panhellenic Symposium of Catalysis" (https://www.16psc.tuc.gr).

Prof. Dr. Ioannis V. Yentekakis
Dr. Paraskevi Panagiotopoulou
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

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Published Papers (11 papers)

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16 pages, 3551 KiB  
Article
Electrochemical Promotion of CO2 Hydrogenation Using a Pt/YSZ Fuel Cell Type Reactor
by Andriana Lymperi, Christos Chatzilias, Fotios Xydas, Eftychia Martino, Georgios Kyriakou and Alexandros Katsaounis
Nanomaterials 2023, 13(13), 1930; https://doi.org/10.3390/nano13131930 - 25 Jun 2023
Cited by 2 | Viewed by 1049
Abstract
The hydrogenation of CO2 is a reaction of key technological and environmental importance, as it contributes to the sustainable production of fuels while assisting in the reduction of a major greenhouse gas. The reaction has received substantial attention over the years within [...] Read more.
The hydrogenation of CO2 is a reaction of key technological and environmental importance, as it contributes to the sustainable production of fuels while assisting in the reduction of a major greenhouse gas. The reaction has received substantial attention over the years within the catalysis and electrocatalysis communities. In this respect, the electrochemical promotion of catalysis (EPOC) has been applied successfully to the CO2 hydrogenation reaction to improve the catalytic activity and selectivity of conductive films supported on solid electrolytes. However, designing an effective electrocatalytic reactor remains a challenge due to the connections required between the electrodes and the external potentiostat/galvanostat. This drawback could be alleviated if the catalytic reaction occurs in a reactor that simultaneously operates as a power generator. In this work, the Electrochemical Promotion of the CO2 hydrogenation reaction in a low-temperature solid oxide electrolyte fuel cell (SOFC) reactor is studied using yttria-stabilized zirconia (YSZ) and a platinum (Pt) electrode catalyst. The system has been studied in two distinct operation modes: (i) when the necessary energy for the electrochemical promotion is produced through the parallel reaction of H2 oxidation (galvanic operation) and (ii) when a galvanostat/potentiostat is used to impose the necessary potential (electrolytic operation). The performance of the fuel cell declines less than 15% in the presence of the reactant mixture (CO2 and H2) while producing enough current to conduct EPOC experiments. During the electrolytic operation of the electrochemical cell, the CO production rate is significantly increased by up to 50%. Full article
(This article belongs to the Special Issue Nanocatalysis for Environmental Protection, Energy, and Green Chemistry)
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12 pages, 2507 KiB  
Article
Quantitative In Situ Monitoring of Cu-Atom Release by Cu2O Nanocatalysts under Photocatalytic CO2 Reduction Conditions: New Insights into the Photocorrosion Mechanism
by Areti Zindrou and Yiannis Deligiannakis
Nanomaterials 2023, 13(11), 1773; https://doi.org/10.3390/nano13111773 - 31 May 2023
Cited by 5 | Viewed by 1183
Abstract
Cu2O is among the most promising photocatalysts for CO2 reduction, however its photocorrosion remains a standalone challenge. Herein, we present an in situ study of the release of Cu ions from Cu2O nanocatalysts under photocatalytic conditions in the [...] Read more.
Cu2O is among the most promising photocatalysts for CO2 reduction, however its photocorrosion remains a standalone challenge. Herein, we present an in situ study of the release of Cu ions from Cu2O nanocatalysts under photocatalytic conditions in the presence of HCO3 as a catalytic substrate in H2O. The Cu-oxide nanomaterials were produced by Flame Spray Pyrolysis (FSP) technology. Using Electron Paramagnetic Resonance (EPR) spectroscopy in tandem with analytical Anodic Stripping Voltammetry (ASV), we monitored in situ the Cu2+ atom release from the Cu2O nanoparticles in comparison with CuO nanoparticles under photocatalytic conditions. Our quantitative, kinetic data show that light has detrimental effect on the photocorrosion of Cu2O and ensuing Cu2+ ion release in the H2O solution, up to 15.7% of its mass. EPR reveals that HCO3 acts as a ligand of the Cu2+ ions, promoting the liberation of {HCO3-Cu} complexes in solution from Cu2O, up to 27% of its mass. HCO3 alone exerted a marginal effect. XRD data show that under prolonged irradiation, part of Cu2+ ions can reprecipitate on the Cu2O surface, creating a passivating CuO layer that stabilizes the Cu2O from further photocorrosion. Including isopropanol as a hole scavenger has a drastic effect on the photocorrosion of Cu2O nanoparticles and suppresses the release of Cu2+ ions to the solution. Methodwise, the present data exemplify that EPR and ASV can be useful tools to help quantitatively understand the solid–solution interface photocorrosion phenomena for Cu2O. Full article
(This article belongs to the Special Issue Nanocatalysis for Environmental Protection, Energy, and Green Chemistry)
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18 pages, 3339 KiB  
Article
Efficient [Fe-Imidazole@SiO2] Nanohybrids for Catalytic H2 Production from Formic Acid
by Christos Gkatziouras, Maria Solakidou and Maria Louloudi
Nanomaterials 2023, 13(10), 1670; https://doi.org/10.3390/nano13101670 - 18 May 2023
Cited by 3 | Viewed by 1365
Abstract
Three imidazole-based hybrid materials, coded as IGOPS, IPS and impyridine@SiO2 nanohybrids, were prepared via the covalent immobilization of N-ligands onto a mesoporous nano-SiO2 matrix for H2 generation from formic acid (FA). BET and HRTEM demonstrated that the immobilization of the [...] Read more.
Three imidazole-based hybrid materials, coded as IGOPS, IPS and impyridine@SiO2 nanohybrids, were prepared via the covalent immobilization of N-ligands onto a mesoporous nano-SiO2 matrix for H2 generation from formic acid (FA). BET and HRTEM demonstrated that the immobilization of the imidazole derivative onto SiO2 has a significant effect on the SSA, average pore volume, and particle size distribution. In the context of FA dehydrogenation, their catalytic activity (TONs, TOFs), stability, and reusability were assessed. Additionally, the homologous homogeneous counterparts were evaluated for comparison purposes. Mapping the redox potential of solution Eh vs. SHE revealed that poly-phosphine PP3 plays an essential role in FA dehydrogenation. On the basis of performance and stability, [Fe2+/IGOPS/PP3] demonstrated superior activity compared to other heterogeneous catalysts, producing 9.82 L of gases (VH2 + CO2) with TONs = 31,778, albeit with low recyclability. In contrast, [Fe2+/IPS/PP3] showed the highest stability, retaining considerable performance after three consecutive uses. With VH2 + CO2 = 7.8 L, [Fe2+/impyridine@SiO2/PP3] activity decreased, and it was no longer recyclable. However, the homogeneous equivalent of [Fe2+/impyridine/PP3] was completely inactive. Raman, FT/IR, and UV/Vis spectroscopy demonstrated that the reduced recyclability of [Fe2+/IGOPS/PP3] and [Fe2+/impyridine@SiO2/PP3] nanohybrids is due to the reductive cleavage of their C-O-C bonds during catalysis. An alternative grafting procedure is proposed, applying here to the grafting of IPS, resulting in its higher stability. The accumulation of water derived from substrate’s feeding causes the inhibition of catalysis. In the case of [Fe2+-imidazole@SiO2] nanohybrids, simple washing and drying result in their re-activation, overcoming the water inhibition. Thus, the low-cost imidazole-based nanohybrids IGOPS and IPS are capable of forming [Fe2+/IGOPS/PP3] and [Fe2+/IPS/PP3] heterogeneous catalytic systems with high stability and performance for FA dehydrogenation. Full article
(This article belongs to the Special Issue Nanocatalysis for Environmental Protection, Energy, and Green Chemistry)
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13 pages, 13327 KiB  
Article
Influence of Natural Mordenite Activation Mode on Its Efficiency as Support of Nickel Catalysts for Biodiesel Upgrading to Renewable Diesel
by Konstantina Fani, Sotiris Lycourghiotis, Kyriakos Bourikas and Eleana Kordouli
Nanomaterials 2023, 13(10), 1603; https://doi.org/10.3390/nano13101603 - 10 May 2023
Cited by 3 | Viewed by 1075
Abstract
In the present work, natural mordenite originated from volcanic soils in Greek islands, activated using HCl solution and HCl solution followed by NaOH solution, was used as support for preparing two metallic nickel catalysts (30 wt.% Ni). The catalysts were thoroughly characterized (XRF, [...] Read more.
In the present work, natural mordenite originated from volcanic soils in Greek islands, activated using HCl solution and HCl solution followed by NaOH solution, was used as support for preparing two metallic nickel catalysts (30 wt.% Ni). The catalysts were thoroughly characterized (XRF, N2 adsorption–desorption, SEM, XRD, TEM, H2-TPR, NH3-TPD) and evaluated for biodiesel upgrading to green (renewable) diesel. Double activation of natural mordenite optimized its supporting characteristics, finally resulting in a supported nickel catalyst with (i) enhanced specific surface area (124 m2 g−1) and enhanced mean pore diameter (14 nm) facilitating mass transfer; (ii) easier nickel phase reduction; (iii) enhanced Ni0 dispersion and thus high active surface; (iv) balanced population of moderate and strong acid sites; (v) resistance to sintering; and (vi) low coke formation. Over the corresponding catalyst, the production of a liquid consisting of 94 wt.% renewable diesel was achieved, after 9 h of reaction at 350 °C and 40 bar H2 pressure, in a semi-batch reactor under solvent-free conditions. Full article
(This article belongs to the Special Issue Nanocatalysis for Environmental Protection, Energy, and Green Chemistry)
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13 pages, 2790 KiB  
Article
The Hydrogenation of Crotonaldehyde on PdCu Single Atom Alloy Catalysts
by Mohammed J. Islam, Marta Granollers Mesa, Amin Osatiashtiani, Martin J. Taylor, Mark A. Isaacs and Georgios Kyriakou
Nanomaterials 2023, 13(8), 1434; https://doi.org/10.3390/nano13081434 - 21 Apr 2023
Cited by 3 | Viewed by 2124
Abstract
Recyclable PdCu single atom alloys supported on Al2O3 were applied to the selective hydrogenation of crotonaldehyde to elucidate the minimum number of Pd atoms required to facilitate the sustainable transformation of an α,β-unsaturated carbonyl molecule. It was found that, by [...] Read more.
Recyclable PdCu single atom alloys supported on Al2O3 were applied to the selective hydrogenation of crotonaldehyde to elucidate the minimum number of Pd atoms required to facilitate the sustainable transformation of an α,β-unsaturated carbonyl molecule. It was found that, by diluting the Pd content of the alloy, the reaction activity of Cu nanoparticles can be accelerated, enabling more time for the cascade conversion of butanal to butanol. In addition, a significant increase in the conversion rate was observed, compared to bulk Cu/Al2O3 and Pd/Al2O3 catalysts when normalising for Cu and Pd content, respectively. The reaction selectivity over the single atom alloy catalysts was found to be primarily controlled by the Cu host surface, mainly leading to the formation of butanal but at a significantly higher rate than the monometallic Cu catalyst. Low quantities of crotyl alcohol were observed over all Cu-based catalysts but not for the Pd monometallic catalyst, suggesting that it may be a transient species converted immediately to butanol and or isomerized to butanal. These results demonstrate that fine-tuning the dilution of PdCu single atom alloy catalysts can leverage the activity and selectivity enhancement, and lead to cost-effective, sustainable, and atom-efficient alternatives to monometallic catalysts. Full article
(This article belongs to the Special Issue Nanocatalysis for Environmental Protection, Energy, and Green Chemistry)
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18 pages, 7788 KiB  
Article
Improved Visible-Light Photocatalytic H2 Evolution of G-C3N4 Nanosheets by Constructing Heterojunctions with Nano-Sized Poly(3-Thiophenecarboxylic Acid) and Coordinating Fe(III)
by Yong Li, Bingmiao Zhang, Xulong Pang, Zhijun Li, Yi Zhang, Ming Hao, Yan Zhu, Chuanli Qin and Liqiang Jing
Nanomaterials 2023, 13(8), 1338; https://doi.org/10.3390/nano13081338 - 12 Apr 2023
Cited by 3 | Viewed by 1622
Abstract
It is highly desirable to enhance the photogenerated charge separation of g-C3N4 by constructing efficient heterojunctions, especially with an additional organic constitution for solar–hydrogen conversion. Herein, g-C3N4 nanosheets have been modified controllably with nano-sized poly(3-thiophenecarboxylic acid) (PTA) [...] Read more.
It is highly desirable to enhance the photogenerated charge separation of g-C3N4 by constructing efficient heterojunctions, especially with an additional organic constitution for solar–hydrogen conversion. Herein, g-C3N4 nanosheets have been modified controllably with nano-sized poly(3-thiophenecarboxylic acid) (PTA) through in situ photopolymerization and then coordinated with Fe(III) via the -COOH groups of modified PTA, forming an interface of tightly contacted nanoheterojunctions between the Fe(III)-coordinated PTA and g-C3N4. The resulting ratio-optimized nanoheterojunction displays a ~4.6-fold enhancement of the visible-light photocatalytic H2 evolution activity compared to bare g-C3N4. Based on the surface photovoltage spectra, measurements of the amount of •OH produced, photoluminescence (PL) spectra, photoelectrochemical curves, and single-wavelength photocurrent action spectra, it was confirmed that the improved photoactivity of g-C3N4 is attributed to the significantly promoted charge separation by the transfer of high-energy electrons from the lowest unoccupied molecular orbital (LUMO) of g-C3N4 to the modified PTA via the formed tight interface, dependent on the hydrogen bond interaction between the -COOH of PTA and the -NH2 of g-C3N4, and the continuous transfer to the coordinated Fe(III) with -OH favorable for connection with Pt as the cocatalyst. This study demonstrates a feasible strategy for solar-light-driven energy production over the large family of g-C3N4 heterojunction photocatalysts with exceptional visible-light activities. Full article
(This article belongs to the Special Issue Nanocatalysis for Environmental Protection, Energy, and Green Chemistry)
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17 pages, 4535 KiB  
Article
Composites of Lignin-Based Biochar with BiOCl for Photocatalytic Water Treatment: RSM Studies for Process Optimization
by Amit Kumar Singh, Dimitrios A. Giannakoudakis, Michael Arkas, Konstantinos S. Triantafyllidis and Vaishakh Nair
Nanomaterials 2023, 13(4), 735; https://doi.org/10.3390/nano13040735 - 15 Feb 2023
Cited by 11 | Viewed by 2290
Abstract
Textile effluents pose a massive threat to the aquatic environment, so, sustainable approaches for environmentally friendly multifunctional remediation methods degradation are still a challenge. In this study, composites consisting of bismuth oxyhalide nanoparticles, specifically bismuth oxychloride (BiOCl) nanoplatelets, and lignin-based biochar were synthesized [...] Read more.
Textile effluents pose a massive threat to the aquatic environment, so, sustainable approaches for environmentally friendly multifunctional remediation methods degradation are still a challenge. In this study, composites consisting of bismuth oxyhalide nanoparticles, specifically bismuth oxychloride (BiOCl) nanoplatelets, and lignin-based biochar were synthesized following a one-step hydrolysis synthesis. The simultaneous photocatalytic and adsorptive remediation efficiency of the Biochar–BiOCl composites were studied for the removal of a benchmark azo anionic dye, methyl orange dye (MO). The influence of various parameters (such as catalyst dosage, initial dye concentration, and pH) on the photo-assisted removal was carried out and optimized using the Box–Behnken Design of RSM. The physicochemical properties of the nanomaterials were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis, nitrogen sorption, and UV–Vis diffuse reflectance spectroscopy (DRS). The maximum dye removal was observed at a catalyst dosage of 1.39 g/L, an initial dye concentration of 41.8 mg/L, and a pH of 3.15. The experiment performed under optimized conditions resulted in 100% degradation of the MO after 60 min of light exposure. The incorporation of activated biochar had a positive impact on the photocatalytic performance of the BiOCl photocatalyst for removing the MO due to favorable changes in the surface morphology, optical absorption, and specific surface area and hence the dispersion of the photo-active nanoparticles leading to more photocatalytic active sites. This study is within the frames of the design and development of green-oriented nanomaterials of low cost for advanced (waste)water treatment applications. Full article
(This article belongs to the Special Issue Nanocatalysis for Environmental Protection, Energy, and Green Chemistry)
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17 pages, 4066 KiB  
Article
Nickel—Alumina Catalysts for the Transformation of Vegetable Oils into Green Diesel: The Role of Preparation Method, Activation Temperature, and Reaction Conditions
by Ioannis Nikolopoulos, George Kogkos, Vasiliki D. Tsavatopoulou, Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis and Alexis Lycourghiotis
Nanomaterials 2023, 13(3), 616; https://doi.org/10.3390/nano13030616 - 03 Feb 2023
Cited by 7 | Viewed by 1431
Abstract
Two nickel alumina catalysts containing 60 wt. % Ni were synthesized by wet impregnation and co-precipitation in order to study the effect of preparation methods on the catalytic efficiency concerning the transformation of sunflower oil into green diesel. The effect of activation temperature [...] Read more.
Two nickel alumina catalysts containing 60 wt. % Ni were synthesized by wet impregnation and co-precipitation in order to study the effect of preparation methods on the catalytic efficiency concerning the transformation of sunflower oil into green diesel. The effect of activation temperature on the catalytic efficiency of the most active catalyst was also studied. The catalysts were characterized using various techniques and which were evaluated in the aforementioned reaction using a semi-batch reactor. The catalyst prepared by co-precipitation exhibited a higher specific surface area and smaller mean crystal size of the nickel nanoparticle (higher nickel metallic surface). These justify its higher efficiency with respect to the corresponding catalyst synthesized by wet impregnation. The increase in the activation temperature from 400 to 600 °C increased the size of the nickel nanoparticles through sintering, thus destroying the small pores. These led to a decrease in the nickel surface and specific surface area and, thus, to a decrease in the catalytic efficiency. The optimization of the reaction conditions over the most active catalyst (prepared by co-precipitation and activated at 400 °C) leads to the complete transformation not only of the sunflower oil (edible oil) but also of waste cooking oil (non-edible oil) into green diesel. The liquid produced after the hydrotreatment for these two feedstocks for 7 h, at H2 pressure 40 bar and temperature 350 °C using 100 mL of oil and 1 g of catalyst was composed of 97 and 96 wt. % of green diesel, respectively. Full article
(This article belongs to the Special Issue Nanocatalysis for Environmental Protection, Energy, and Green Chemistry)
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15 pages, 2589 KiB  
Article
Effect of Steam to Carbon Dioxide Ratio on the Performance of a Solid Oxide Cell for H2O/CO2 Co-Electrolysis
by Naouma Bimpiri, Argyro Konstantinidou, Dimitrios Tsiplakides, Stella Balomenou and Kalliopi Maria Papazisi
Nanomaterials 2023, 13(2), 299; https://doi.org/10.3390/nano13020299 - 11 Jan 2023
Cited by 1 | Viewed by 2263
Abstract
The mixture of H2 and CO, the so-called syngas, is the value-added product of H2O and CO2 co-electrolysis and the feedstock for the production of value-added chemicals (mainly through Fischer-Tropsch). The H2/CO ratio determines the process in [...] Read more.
The mixture of H2 and CO, the so-called syngas, is the value-added product of H2O and CO2 co-electrolysis and the feedstock for the production of value-added chemicals (mainly through Fischer-Tropsch). The H2/CO ratio determines the process in which syngas will be utilized and the type of chemicals it will produce. In the present work, we investigate the effect of H2O/CO2 (steam/carbon dioxide, S/C) ratio of 0.5, 1 and 2 in the feed, on the electrochemical performance of an 8YSZ electrolyte-supported solid oxide cell and the H2/CO ratio in the outlet, under co-electrolysis at 900 °C. The B-site iron doped lanthanum strontium chromite La0.75Sr0.25Cr0.9Fe0.1O3-δ (LSCF) is used as fuel electrode material while as oxygen electrode the state-of-the art LSM perovskite is employed. LSCF is a mixed ionic-electronic conductor (MIEC) operating both under a reducing and oxidizing atmosphere. The cell is electrochemically characterized under co-electrolysis conditions both in the presence and absence of hydrogen in the feed of the steam and carbon dioxide mixtures. The results indicate that under the same concentration of hydrogen and different S/C ratios, the same electrochemical performance with a maximum current density of approximately 400 mA cm−2 is observed. However, increasing p(H2) in the feed results in higher OCV, smaller iV slope and Rp values. Furthermore, the maximum current density obtained from the cell does not seem to be affected by whether H2 is present or absent from the fuel electrode feed but has a significant effect on the H2/CO ratio in the analyzed outlet stream. Moreover, the H2/CO ratio seems to be identical under polarization at different current density values. Remarkably, the performance of the LSCF perovskite fuel electrode is not compromised by the exposure to oxidizing conditions, showcasing that this class of electrocatalysts retains their reactivity in oxidizing, reducing, and humid environments. Full article
(This article belongs to the Special Issue Nanocatalysis for Environmental Protection, Energy, and Green Chemistry)
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19 pages, 5007 KiB  
Article
Development of a Multi-Enzymatic Biocatalytic System through Immobilization on High Quality Few-Layer bio-Graphene
by Christina Alatzoglou, Michaela Patila, Archontoula Giannakopoulou, Konstantinos Spyrou, Feng Yan, Wenjian Li, Nikolaos Chalmpes, Angeliki C. Polydera, Petra Rudolf, Dimitrios Gournis and Haralambos Stamatis
Nanomaterials 2023, 13(1), 127; https://doi.org/10.3390/nano13010127 - 26 Dec 2022
Cited by 6 | Viewed by 1925
Abstract
In this work, we report the green production of few-layer bio-Graphene (bG) through liquid exfoliation of graphite in the presence of bovine serum albumin. Microscopic characterization evaluated the quality of the produced nanomaterial, showing the presence of 3–4-layer graphene. Moreover, spectroscopic techniques also [...] Read more.
In this work, we report the green production of few-layer bio-Graphene (bG) through liquid exfoliation of graphite in the presence of bovine serum albumin. Microscopic characterization evaluated the quality of the produced nanomaterial, showing the presence of 3–4-layer graphene. Moreover, spectroscopic techniques also confirmed the quality of the resulted bG, as well as the presence of bovine serum albumin on the graphene sheets. Next, for the first time, bG was used as support for the simultaneous covalent co-immobilization of three enzymes, namely β-glucosidase, glucose oxidase, and horseradish peroxidase. The three enzymes were efficiently co-immobilized on bG, demonstrating high immobilization yields and activity recoveries (up to 98.5 and 90%, respectively). Co-immobilization on bG led to an increase of apparent KM values and a decrease of apparent Vmax values, while the stability of the nanobiocatalysts prevailed compared to the free forms of the enzymes. Co-immobilized enzymes exhibited high reusability, preserving a significant part of their activity (up to 72%) after four successive catalytic cycles at 30 °C. Finally, the tri-enzymatic nanobiocatalytic system was applied in three-step cascade reactions, involving, as the first step, the hydrolysis of p-Nitrophenyl-β-D-Glucopyranoside and cellobiose. Full article
(This article belongs to the Special Issue Nanocatalysis for Environmental Protection, Energy, and Green Chemistry)
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14 pages, 4263 KiB  
Article
Defect Chemistry and Chemical Looping Performance of La1−xMxMnO3 (M = Sr, Ca, (x = 0–0.5)) Perovskites
by Antigoni Evdou, Theofilos Georgitsis, Charitini Matsouka, Eleni Pachatouridou, Eleni Iliopoulou and Vassilios Zaspalis
Nanomaterials 2022, 12(19), 3461; https://doi.org/10.3390/nano12193461 - 03 Oct 2022
Cited by 5 | Viewed by 1591
Abstract
La1−xMxMnO3 (M = Sr, Ca, (x = 0–0.5)) materials of the perovskite structure are synthesized by a co-precipitation method. They are subsequently investigated for their performance in a chemical looping process (fuel CH4) using thermogravimetric analysis [...] Read more.
La1−xMxMnO3 (M = Sr, Ca, (x = 0–0.5)) materials of the perovskite structure are synthesized by a co-precipitation method. They are subsequently investigated for their performance in a chemical looping process (fuel CH4) using thermogravimetric analysis with simultaneous reaction. The goal of this work is to determine the relation between the defect chemistry of the materials and their behavior in chemical looping processes. A defect model is proposed that provides an explanation of the dependency of the Oxygen Transfer Capacity and of the CO2/CO selectivity on composition. It appeared that the fuel may react with various types of oxygen available within the materials, generated by different mechanisms. The relative amounts of each oxygen type determine the CO2/CO selectivity and depend on the material composition as well as on the partial pressure of oxygen used for regenerating the materials. Full article
(This article belongs to the Special Issue Nanocatalysis for Environmental Protection, Energy, and Green Chemistry)
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