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Search Results (403)

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Keywords = Fe3O4/CuO/C

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24 pages, 9486 KiB  
Article
StMAPKK1 Enhances Thermotolerance in Potato (Solanum tuberosum L.) by Enhancing Antioxidant Defense and Photosynthetic Efficiency Under Heat Stress
by Xi Zhu, Yasir Majeed, Kaitong Wang, Xiaoqin Duan, Nengkang Guan, Junfu Luo, Haifei Zheng, Huafen Zou, Hui Jin, Zhuo Chen and Yu Zhang
Plants 2025, 14(15), 2289; https://doi.org/10.3390/plants14152289 - 24 Jul 2025
Viewed by 233
Abstract
The functional role of MAPKK genes in potato (Solanum tuberosum L.) under high-temperature stress remains unexplored, despite their critical importance in stress signaling and yield protection. We characterized StMAPKK1, a novel group D MAPKK localized to plasma membrane/cytoplasm. Quantitative real-time polymerase chain [...] Read more.
The functional role of MAPKK genes in potato (Solanum tuberosum L.) under high-temperature stress remains unexplored, despite their critical importance in stress signaling and yield protection. We characterized StMAPKK1, a novel group D MAPKK localized to plasma membrane/cytoplasm. Quantitative real-time polymerase chain reaction (qRT-PCR) revealed cultivar-specific upregulation in potato (‘Atlantic’ and ‘Desiree’) leaves under heat stress (25 °C, 30 °C, and 35 °C). Transgenic lines overexpressing (OE) StMAPKK1 exhibited elevated antioxidant enzyme activity, including ascorbate peroxidase (APX), catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD), mitigating oxidative damage. Increased proline and chlorophyll accumulation and reduced oxidative stress markers, hydrogen peroxide (H2O2) and malondialdehyde (MDA), indicate improved cellular redox homeostasis. The upregulation of key antioxidant and heat stress-responsive genes (StAPX, StCAT1/2, StPOD12/47, StFeSOD2/3, StMnSOD, StCuZnSOD1/2, StHSFA3 and StHSP20/70/90) strengthened the enzymatic defense system, enhanced thermotolerance, and improved photosynthetic efficiency, with significant improvements in net photosynthetic rate (Pn), transpiration rate (E), and stomatal conductance (Gs) under heat stress (35 °C) in StMAPKK1-OE plants. Superior growth and biomass (plant height, plant and its root fresh and dry weights, and tuber yield) accumulation, confirming the positive role of StMAPKK1 in thermotolerance. Conversely, RNA interference (RNAi)-mediated suppression of StMAPKK1 led to a reduction in enzymatic activity, proline content, and chlorophyll levels, exacerbating oxidative stress. Downregulation of antioxidant-related genes impaired ROS scavenging capacity and declines in photosynthetic efficiency, growth, and biomass, accompanied by elevated H2O2 and MDA accumulation, highlighting the essential role of StMAPKK1 in heat stress adaptation. These findings highlight StMAPKK1’s potential as a key genetic target for breeding heat-tolerant potato varieties, offering a foundation for improving crop resilience in warming climates. Full article
(This article belongs to the Special Issue Cell Physiology and Stress Adaptation of Crops)
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19 pages, 4875 KiB  
Article
Synthesis, Characterization, and Biological Evaluation of Some 3d Metal Complexes with 2-Benzoylpyridine 4-Allylthiosemicarbazone
by Vasilii Graur, Ianina Graur, Pavlina Bourosh, Victor Kravtsov, Carolina Lozan-Tirsu, Greta Balan, Olga Garbuz, Victor Tsapkov and Aurelian Gulea
Inorganics 2025, 13(7), 249; https://doi.org/10.3390/inorganics13070249 - 21 Jul 2025
Viewed by 259
Abstract
The eight new copper(II), nickel(II), zinc(II), and iron(III) coordination compounds [Cu(L)Cl]2 (1), [Cu(L)Br]2 (2), [Cu(L)(NO3)]2 (3), [Cu(phen)(L)]NO3 (4), [Ni(HL)2](NO3)2·H2O (5 [...] Read more.
The eight new copper(II), nickel(II), zinc(II), and iron(III) coordination compounds [Cu(L)Cl]2 (1), [Cu(L)Br]2 (2), [Cu(L)(NO3)]2 (3), [Cu(phen)(L)]NO3 (4), [Ni(HL)2](NO3)2·H2O (5), [Ni(HL)2]Cl2 (6), [Zn(L)2]·0.125H2O (7), and [Fe(L)2]Cl (8), where HL stands for 2-benzoylpyridine 4-allylthiosemicarbazone, were synthesized and characterized. 1H, 13C NMR, and FTIR spectroscopies were used for characterization of the HL thiosemicarbazone. The elemental analysis, the FTIR spectroscopy, and the study of molar electrical conductivity were used for characterization of the coordination compounds 18. Also, the crystal structures of HL, its salts ([H2L]Cl; [H2L]NO3), and complexes 1, 3, 5, 7, and 8 were determined using single-crystal X-ray diffraction analysis. Complexes 5, 7, 8 have mononuclear structures, while copper(II) complexes 1 and 3 have a dimeric structure with the sulfur atoms of the thiosemicarbazone ligand bridging two copper atoms together. Thiosemicarbazone HL and the complexes manifest antibacterial and antifungal activities. The studied substances are more active towards Gram-negative bacteria than towards Gram-positive bacteria and fungi. Complex 1 is the most active one towards Gram-positive bacteria and C. albicans, while the introduction of 1,10-phenanthroline into the inner sphere enhances the activity towards Gram-negative bacteria. Thiosemicarbazone and complexes 6 and 7 manifest antiradical activity that exceeds the activity of Trolox. HL and complex 1 manifest antiproliferative activity towards HL-60 cancer cells which exceeds the activity of their analogs with 2-formyl-/2-acetylpyridine 4-allylthiosemicarbazone. Full article
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19 pages, 5973 KiB  
Article
Chitosan-Modified SBA-15 as a Support for Transition Metal Catalysts in Cyclohexane Oxidation and Photocatalytic Hydrogen Evolution
by Assemgul S. Auyezkhanova, Alima K. Zharmagambetova, Eldar T. Talgatov, Aigul I. Jumekeyeva, Sandugash N. Akhmetova, Zhannur K. Myltykbayeva, Imge Kalkan, Atıf Koca, Akzhol A. Naizabayev and Aigul T. Zamanbekova
Catalysts 2025, 15(7), 650; https://doi.org/10.3390/catal15070650 - 3 Jul 2025
Viewed by 514
Abstract
This work aims to study the catalytic properties of Fe, Cr, and Cu catalysts deposited on chitosan–silica (SBA-15) composites in liquid phase oxidation of cyclohexane (CH) with H2O2 and photocatalytic hydrogen evolution reaction. The catalysts were obtained by consecutive adsorption [...] Read more.
This work aims to study the catalytic properties of Fe, Cr, and Cu catalysts deposited on chitosan–silica (SBA-15) composites in liquid phase oxidation of cyclohexane (CH) with H2O2 and photocatalytic hydrogen evolution reaction. The catalysts were obtained by consecutive adsorption of chitosan (CS) and metal ions (Fe3+, Cr3+, Cu2+) on SBA-15 at ambient conditions. Characterization of the catalysts by XRD, IR spectroscopy, XPS, TEM, SEM, etc., showed the CS and metal ion adsorption on the solid support. Modification with CS provided better immobilization of the metal ions on SBA-15. The synthesized catalysts demonstrated different performance in liquid phase oxidation of cyclohexane with H2O2 under mild conditions at 40 °C and atmospheric pressure. Cyclohexane conversion on Fe–CS/SBA-15 (18.5%) and Cr–CS/SBA-15 (21.6%) was higher than on Cu–CS/SBA-15 (9.3%). The influence of different conditions of the reaction such as time, temperature, catalyst dosage, substrate and oxidant ratio on cyclohexane conversion in the presence of the most efficient Cr–CS/SBA-15 catalyst was also studied. The optimal reaction conditions were found to be the following: duration of reaction—4 h, temperature of reaction—50 °C, mcat—0.03 g, a substrate/H2O2 ratio of 1:3. In addition, Cr–CS/SBA-15 and Fe–CS/SBA-15 catalysts were studied in a photocatalytic H2 evolution reaction. The Fe-containing catalyst demonstrated superior efficiency in photocatalytic H2 evolution. The total volume of hydrogen produced within 3 h was 103 mL/g. Thus, this study demonstrates that chitosan possesses promising potential in the design of the supported catalysts for cyclohexane oxidation and photocatalytic hydrogen evolution reactions. Full article
(This article belongs to the Special Issue Homogeneous and Heterogeneous Catalytic Oxidation and Reduction)
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17 pages, 7952 KiB  
Article
Achyrophanite, (K,Na)3(Fe3+,Ti,Al,Mg)5O2(AsO4)5, a New Mineral with the Novel Structure Type from Fumarolic Exhalations of the Tolbachik Volcano, Kamchatka, Russia
by Igor V. Pekov, Natalia V. Zubkova, Natalia N. Koshlyakova, Dmitry I. Belakovskiy, Marina F. Vigasina, Atali A. Agakhanov, Sergey N. Britvin, Anna G. Turchkova, Evgeny G. Sidorov, Pavel S. Zhegunov and Dmitry Yu. Pushcharovsky
Minerals 2025, 15(7), 706; https://doi.org/10.3390/min15070706 - 2 Jul 2025
Viewed by 280
Abstract
The new mineral achyrophanite (K,Na)3(Fe3+,Ti,Al,Mg)5O2(AsO4)5 was found in high-temperature sublimates of the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, [...] Read more.
The new mineral achyrophanite (K,Na)3(Fe3+,Ti,Al,Mg)5O2(AsO4)5 was found in high-temperature sublimates of the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with aphthitalite-group sulfates, hematite, alluaudite-group arsenates (badalovite, calciojohillerite, johillerite, nickenichite, hatertite, and khrenovite), ozerovaite, pansnerite, arsenatrotitanite, yurmarinite, svabite, tilasite, katiarsite, yurgensonite, As-bearing sanidine, anhydrite, rutile, cassiterite, and pseudobrookite. Achyrophanite occurs as long-prismatic to acicular or, rarer, tabular crystals up to 0.02 × 0.2 × 1.5 mm, which form parallel, radiating, bush-like, or chaotic aggregates up to 3 mm across. It is transparent, straw-yellow to golden yellow, with strong vitreous luster. The mineral is brittle, with (001) perfect cleavage. Dcalc is 3.814 g cm–3. Achyrophanite is optically biaxial (+), α = 1.823(7), β = 1.840(7), γ = 1.895(7) (589 nm), 2V (meas.) = 60(10)°. Chemical composition (wt.%, electron microprobe) is: Na2O 3.68, K2O 9.32, CaO 0.38, MgO 1.37, MnO 0.08, CuO 0.82, ZnO 0.48, Al2O3 2.09, Fe2O3 20.42, SiO2 0.12, TiO2 7.35, P2O5 0.14, V2O5 0.33, As2O5 51.88, SO3 1.04, and total 99.40. The empirical formula calculated based on 22 O apfu is Na1.29K2.15Ca0.07Mg0.34Mn0.01Cu0.11Zn0.06Al0.44Fe3+2.77Ti1.00Si0.02P0.02S0.14V0.04As4.90O22. Achyrophanite is orthorhombic, space group P2221, a = 6.5824(2), b = 13.2488(4), c = 10.7613(3) Å, V = 938.48(5) Å3 and Z = 2. The strongest reflections of the PXRD pattern [d,Å(I)(hkl)] are 5.615(59)(101), 4.174(42)(022), 3.669(31)(130), 3.148(33)(103), 2.852(43)(141), 2.814(100)(042, 202), 2.689(29)(004), and 2.237(28)(152). The crystal structure of achyrophanite (solved from single-crystal XRD data, R = 4.47%) is unique. It is based on the octahedral-tetrahedral M-T-O pseudo-framework (M = Fe3+ with admixed Ti, Al, Mg, Na; T = As5+). Large-cation A sites (A = K, Na) are located in the channels of the pseudo-framework. The achyrophanite structure can be described as stuffed, with the defect heteropolyhedral pseudo-framework derivative of the orthorhombic Fe3+AsO4 archetype. The mineral is named from the Greek άχυρον, straw, and φαίνομαι, to appear, in allusion to its typical straw-yellow color and long prismatic habit of crystals. Full article
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27 pages, 3223 KiB  
Article
Chloroprene and Butadiene Rubber (CR/BR) Blends Cross-Linked with Metal Oxides: INFLUENCE of Vulcanization Temperature on Their Rheological, Mechanical, and Thermal Properties
by Aleksandra Smejda-Krzewicka and Konrad Mrozowski
Molecules 2025, 30(13), 2780; https://doi.org/10.3390/molecules30132780 - 27 Jun 2025
Viewed by 281
Abstract
This paper aimed to evaluate the effect of cross-linking temperature on the rheological, mechanical, and thermal properties of CR/BR compositions cross-linked with zinc oxide, iron(III) oxide, or copper(II) oxide. Properties of CR/BR compounds were studied at four temperatures: 140, 160, 180, and 200 [...] Read more.
This paper aimed to evaluate the effect of cross-linking temperature on the rheological, mechanical, and thermal properties of CR/BR compositions cross-linked with zinc oxide, iron(III) oxide, or copper(II) oxide. Properties of CR/BR compounds were studied at four temperatures: 140, 160, 180, and 200 °C. The lowest activation energy of vulcanization was shown by blends cross-linked with ZnO, and the highest activation energy of vulcanization was shown by samples with Fe2O3. Blends cured with ZnO or Fe2O3 showed higher cross-linking activity than CuO. Higher temperatures enhanced the degree of cross-linking in the CR/BR composite cured with ZnO or CuO but slightly reduced it for the CR/BR/Fe2O3 vulcanizates. The highest tensile strength was observed for the CR/BR/Fe2O3 product. However, compositions cured with ZnO exhibited the best aging resistance. The CR/BR compounds cured with ZnO at high temperatures had the highest tear strength (16.8 N/mm), while samples containing CuO as a curing agent showed declining tear strength with temperature. DSC confirmed a single glass transition (~36 °C), indicating good elastomers dispersion. Infrared and SEM analyses confirmed effective cross-linking and blend compatibility. Full article
(This article belongs to the Section Materials Chemistry)
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11 pages, 2330 KiB  
Article
Separations of Strategic Metals from Spent Electronic Waste Using “Green Methods”
by Urszula Domańska, Anna Wiśniewska and Zbigniew Dąbrowski
Separations 2025, 12(6), 167; https://doi.org/10.3390/separations12060167 - 18 Jun 2025
Viewed by 442
Abstract
Next-generation recycling technologies must be urgently innovated to tackle huge volumes of spent batteries, photovoltaic panels or printed circuit boards (WPCBs). Current e-waste recycling industrial technology is dominated by traditional recycling technologies. Herein, ionic liquids (ILs), deep eutectic solvents (DESs) and promising oxidizing [...] Read more.
Next-generation recycling technologies must be urgently innovated to tackle huge volumes of spent batteries, photovoltaic panels or printed circuit boards (WPCBs). Current e-waste recycling industrial technology is dominated by traditional recycling technologies. Herein, ionic liquids (ILs), deep eutectic solvents (DESs) and promising oxidizing additives that can overcome some traditional recycling methods of metal ions from e-waste, used in our works from last year, are presented. The unique chemical environments of ILs and DESs, with the application of low-temperature extraction procedures, are important environmental aspects known as “Green Methods”. A closed-loop system for recycling zinc and manganese from the “black mass” (BM) of waste, Zn-MnO2 batteries, is presented. The leaching process achieves a high efficiency and distribution ratio using the composition of two solvents (Cyanex 272 + diethyl phosphite (DPh)) for Zn(II) extraction. High extraction efficiency with 100% zinc and manganese recovery is also achieved using DESs (cholinum chloride/lactic acid, 1:2, DES 1, and cholinum chloride/malonic acid, 1:1, DES 2). New, greener recycling approaches to metal extraction from the BM of spent Li-ion batteries are presented with ILs ([N8,8,8,1][Cl], (Aliquat 336), [P6,6,6,14][Cl], [P6,6,6,14][SCN] and [Benzet][TCM]) eight DESs, Cyanex 272 and D2EHPA. A high extraction efficiency of Li(I) (41–92 wt%) and Ni(II) (37–52 wt%) using (Cyanex 272 + DPh) is obtained. The recovery of Ni(II) and Cd(II) from the BM of spent Ni-Cd batteries is also demonstrated. The extraction efficiency of DES 1 and DES 2, contrary to ILs ([P6,6,6,14][Cl] and [P6,6,6,14][SCN]), is at the level of 30 wt% for Ni(II) and 100 wt% for Cd(II). In this mini-review, the option to use ILs, DESs and Cyanex 272 for the recovery of valuable metals from end-of-life WPCBs is presented. Next-generation recycling technologies, in contrast to the extraction of metals from acidic leachate preceded by thermal pre-treatment or from solid material only after thermal pre-treatment, have been developed with ILs and DESs using the ABS method, as well as Cyanex 272 (only after the thermal pre-treatment of WPCBs), with a process efficiency of 60–100 wt%. In this process, four new ILs are used: didecyldimethylammonium propionate, [N10,10,1,1][C2H5COO], didecylmethylammonium hydrogen sulphate, [N10,10,1,H][HSO4], didecyldimethylammonium dihydrogen phosphate, [N10,10,1,1][H2PO4], and tetrabutylphosphonium dihydrogen phosphate, [P4,4,4,4][H2PO4]. The extraction of Cu(II), Ag(I) and other metals such as Al(III), Fe(II) and Zn(II) from solid WPCBs is demonstrated. Various additives are used during the extraction processes. The Analyst 800 atomic absorption spectrometer (FAAS) is used for the determination of metal content in the solid BM. The ICP-OES method is used for metal analysis. The obtained results describe the possible application of ILs and DESs as environmental media for upcycling spent electronic wastes. Full article
(This article belongs to the Section Materials in Separation Science)
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9 pages, 1926 KiB  
Communication
Surface Modification of Fe-Based Perovskite Oxide via Sr0.95Ce0.05CoO3−δ Infiltration: A Strategy for Thermochemical Stability
by Taeheun Lim and Heesoo Lee
Nanomaterials 2025, 15(12), 934; https://doi.org/10.3390/nano15120934 - 16 Jun 2025
Viewed by 598
Abstract
Cobalt-based perovskite oxides exhibit remarkable catalytic activity owing to abundant oxygen vacancies and mixed ionic–electronic conductivity, but they suffer from structural instability. In contrast, iron-based perovskite oxides are thermochemically stable under oxidizing and reducing conditions but are catalytically limited. To combine these complementary [...] Read more.
Cobalt-based perovskite oxides exhibit remarkable catalytic activity owing to abundant oxygen vacancies and mixed ionic–electronic conductivity, but they suffer from structural instability. In contrast, iron-based perovskite oxides are thermochemically stable under oxidizing and reducing conditions but are catalytically limited. To combine these complementary properties, a composite perovskite oxide was designed and prepared by infiltrating Sr0.95Ce0.05CoO3−δ (SCC) into Ba0.5Sr0.5Fe0.8Cu0.2O3−δ (BSFC). The SCC precursor solution was dropwise applied to a BSFC|SDC|BSFC symmetric cell and heat treated. Surface morphology and compositional analyses confirmed the distribution of SCC nanoparticles on the BSFC surface. High-temperature X-ray diffraction and Rietveld refinement results revealed that both BSFC and SCC retained the cubic perovskite structure (space group Pm-3m) at room temperature. No phase transition or secondary phase formation was observed during heating from 200 to 800 °C, and the peak shifts are attributed to thermal expansion and possible oxygen loss at elevated temperatures. Upon cooling, the diffraction patterns returned to their initial state, confirming a high-temperature structural stability. XPS analysis showed an increase in the satellite peak intensity associated with Fe3+ after SCC infiltration, and the average oxidation state of Fe decreased from 3.52 (BSFC) to 3.49 (composite perovskite oxide). The O 1s spectra revealed a higher relative content of surface-adsorbed oxygen species in the composite, indicating increased oxygen vacancy formation. Full article
(This article belongs to the Section Nanocomposite Materials)
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13 pages, 4057 KiB  
Article
Enhanced Anionic Redox Reaction of Na-Layered Li-Containing Mn-Based Cathodes by Cu-Mediated Reductive Coupling Mechanism
by Danyang Li, Can Liu, Shu Zhao, Fujie Li, Hao Li, Chao Wang and Xiu Song Zhao
Nanomaterials 2025, 15(12), 893; https://doi.org/10.3390/nano15120893 - 10 Jun 2025
Viewed by 394
Abstract
Na-layered Li-containing Mn-based cathodes (NaxLiyMn1-yO2, NLMOs) with additional Na+ storage ability resulting from the anionic redox reaction (ARR) hold great promise for sodium-ion batteries (NIBs). However, practical applications of NLMOs encounter challenges, such as [...] Read more.
Na-layered Li-containing Mn-based cathodes (NaxLiyMn1-yO2, NLMOs) with additional Na+ storage ability resulting from the anionic redox reaction (ARR) hold great promise for sodium-ion batteries (NIBs). However, practical applications of NLMOs encounter challenges, such as migration of transition metal Mn, loss of lattice oxygen, and voltage decay during cycling. Here, we show that Cu plays an important role in enhancing the ARR via the reductive coupling mechanism (RCM). Results shows that a Cu2+/Fe3+ modified NLMO sample delivers a Na+ storage capacity as high as 174 mA h g−1 at 0.2C, higher than that of a Zn2+/Fe3+ modified NLMO sample (130 mA h g−1) and NLMO (154 mA h g−1). Both in situ and ex situ characterization results indicate that the obvious improvement in the electrochemical performance of the Cu2+/Fe3+ modified NLMO is due to the additional overlaps between the Cu 3d and O 2p orbitals, which is beneficial for the RCM. As a result, the ARR is enhanced so as to increase the Na+ storage capacity. Full article
(This article belongs to the Section Energy and Catalysis)
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18 pages, 932 KiB  
Article
Multi-Element Determination in Wild and Cultivated Edible Mushrooms from the Brazilian Atlantic Forest Using Microwave-Induced Plasma Optical Emission Spectrometry (MIP OES)
by Eliabe Sousa da Silva, Jorge Machado Freitas, João Pedro Cezário Brandão, Ivana Ferreira Simões, Alexandre Rafael Lenz, Mariana de Paula Drewinski, Ágata Carvalho Morais, Nelson Menolli and Aníbal de Freitas Santos
Analytica 2025, 6(2), 21; https://doi.org/10.3390/analytica6020021 - 4 Jun 2025
Viewed by 636
Abstract
Edible mushrooms are macroscopic fungi that have been recognized as the “new superfoods” due to their high nutritional and medicinal values. The aim of this study was to develop and optimize a method for the wet digestion of edible mushrooms using a closed [...] Read more.
Edible mushrooms are macroscopic fungi that have been recognized as the “new superfoods” due to their high nutritional and medicinal values. The aim of this study was to develop and optimize a method for the wet digestion of edible mushrooms using a closed digestion block for the determination of macro- and micronutrients (Ca, Cr, Cu, Fe, K, Mg, Mn, Ni, and Zn) using microwave-induced plasma emission spectrometry (MIP OES). For the digestion of the samples, a 23 factorial design was used to evaluate the amount of HNO3 65% (m m−1), H2O2 30% (m m−1) and the digestion time, in 500 mg of the sample (dry and crushed) at 200° C. The method was applied to eleven species of edible or medicinal mushrooms (edible cultivated from wild strains, wild edible, and commercials medicinal). The average concentrations (in mg kg−1) showed higher levels of K (1442.85–17,534.97), Mg (1295.40–13,550.72), Fe (11.33–27.38), Zn (28.86–36.09), and Mn (10.22–10.97). This study contributed to the determination of the multi-element composition and nutritional potential of edible mushrooms from Brazil. Full article
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16 pages, 2310 KiB  
Article
Prediction and Screening of Lead-Free Double Perovskite Photovoltaic Materials Based on Machine Learning
by Juan Wang, Yizhe Wang, Xiaoqin Liu and Xinzhong Wang
Molecules 2025, 30(11), 2378; https://doi.org/10.3390/molecules30112378 - 29 May 2025
Viewed by 620
Abstract
The search for stable, lead-free perovskite materials is critical for developing efficient and environmentally friendly energy solutions. In this study, machine learning methods were applied to predict the bandgap and formation energy of double perovskites, aiming to identify promising photovoltaic candidates. A dataset [...] Read more.
The search for stable, lead-free perovskite materials is critical for developing efficient and environmentally friendly energy solutions. In this study, machine learning methods were applied to predict the bandgap and formation energy of double perovskites, aiming to identify promising photovoltaic candidates. A dataset of 1053 double perovskites was extracted from the Materials Project database, with 50 feature descriptors generated. Feature selection was carried out using Pearson correlation and mRMR methods, and 23 key features for bandgap prediction and 18 key features for formation energy prediction were determined. Four algorithms, including gradient-boosting regression (GBR), random forest regression (RFR), LightGBM, and XGBoost, were evaluated, with XGBoost demonstrating the best performance (R2 = 0.934 for bandgap, R2 = 0.959 for formation energy; MAE = 0.211 eV and 0.013 eV/atom). The SHAP (Shapley Additive Explanations) analysis revealed that the X-site electron affinity positively influences the bandgap, while the B″-site first and third ionization energies exhibit strong negative effects. Formation energy is primarily governed by the X-site first ionization energy and the electronegativities of the B′ and B″ sites. To identify optimal photovoltaic materials, 4573 charge-neutral double perovskites were generated via elemental substitution, with 2054 structurally stable candidates selected using tolerance and octahedral factors. The XGBoost model predicted bandgaps, yielding 99 lead-free double perovskites with ideal bandgaps (1.3~1.4 eV). Among them, four candidates are known compounds according to the Materials Project database, namely Ca2NbFeO6, Ca2FeTaO6, La2CrFeO6, and Cs2YAgBr6, while the remaining 95 candidate perovskites are unknown compounds. Notably, X-site elements (Se, S, O, C) and B″-site elements (Pd, Ir, Fe, Ta, Pt, Cu) favor narrow bandgap formation. These findings provide valuable guidance for designing high-performance, non-toxic photovoltaic materials. Full article
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16 pages, 16751 KiB  
Article
The Effect of Adding Different Elements (Mg, Fe, Cu, and Ce) on the Properties of NiCo2OX for CO-Catalyzed Oxidation
by Jiefeng Wang, Zhili Chen, Tianqi Cao, Junsheng Yang, Yijian Kuang and Jiangang Kang
Materials 2025, 18(11), 2554; https://doi.org/10.3390/ma18112554 - 29 May 2025
Viewed by 466
Abstract
In this experiment, NiCo2Ox catalysts, with different elements added (Mg, Fe, Cu, and Ce), were prepared using the co-precipitation method to investigate their catalytic performance for carbon monoxide, as well as their water resistance and sulfur resistance. Combined with the [...] Read more.
In this experiment, NiCo2Ox catalysts, with different elements added (Mg, Fe, Cu, and Ce), were prepared using the co-precipitation method to investigate their catalytic performance for carbon monoxide, as well as their water resistance and sulfur resistance. Combined with the sintering flue gas environment of Baosteel Zhanjiang Iron and Steel Co., Ltd., it provides a reference for the catalytic oxidation of CO in complex environments. The results reveal that the Fe-added catalysts exhibited a better CO catalytic performance and possessed good redox properties, and the Fe metal ion-added NiCo2Ox catalysts showed a CO catalytic efficiency of 91.72% at 100 °C. Meanwhile, the Fe-added catalysts had the strongest resistance to water, with a conversion of 98.37% to CO at 140 °C, and with 10% water vapor. The Ce-added catalyst showed a better SO2 resistance and hybrid resistance of SO2 and H2O. Under the condition of sulfur addition, the CO conversion of the Ce-added catalyst was as high as 63.07% after 4 h of SO2 introduction, and the efficiency could be restored to 100% after cutting off the supply of SO2. Under the conditions of sulfur addition and water addition, the CO conversion of the catalyst was 98.23% after cutting off the SO2. Full article
(This article belongs to the Topic Application of Nanomaterials in Environmental Analysis)
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18 pages, 4195 KiB  
Article
Study of the Process of Sorption of Iron and Copper from Sulfuric Acid in Their Joint Presence by Natural Zeolite
by Raushan Kaiynbayeva, Raissa Chernyakova, Gita Sultanbayeva, Nazym Kozhabekova, Umirzak Jussipbekov and Ersin Tussupkaliyev
Crystals 2025, 15(6), 494; https://doi.org/10.3390/cryst15060494 - 22 May 2025
Viewed by 359
Abstract
The most promising method for the purification of concentrated technical sulfuric acid is the purification sorption method, which is the most effective and innovative, using a natural sorbent. Study of the process of sorption of iron and copper cations from concentrated technical sulfuric [...] Read more.
The most promising method for the purification of concentrated technical sulfuric acid is the purification sorption method, which is the most effective and innovative, using a natural sorbent. Study of the process of sorption of iron and copper cations from concentrated technical sulfuric acid by a natural zeolite. The specific surface area of the zeolite isolated from reactive sulfuric acid is 4.781 m2/g. The true absorption volume in the zeolite after the purification of sulfuric acid decreases to a value of 147.0068 mL/g for a zeolite sample. The adsorption pore volume for the zeolite after the acid purification calculated from the obtained results is 0.229 mL/g. The physicochemical methods of analysis (NGR, IR, X-ray diffraction, DTA, porosimetry, electron microscopy) and chemical methods revealed that in concentrated sulfuric acid the Fe–O bonds of octahedrons and SiO bonds of tetrahedrons of the zeolite framework are stable. The sorption process was carried out under conditions of a room temperature of T = 25 °C, the ratio “zeolite: H2SO4” of 10:100, and a process time of 5–50 min. The specified concentration of the Fe and Cu cations was created by introducing the calculated amount of FeSO4·7H2O and CuSO4·5H2O, in order to identify the patterns of the sorption process of copper and iron in their joint presence (CFe > CCu; CFe = CCu). The regularities of sorption of iron and copper cations by zeolite in their joint presence on the model system “H2SO4–zeolite–Fe–Cu” were studied and selective sorption capacity of zeolite with respect to iron cations was revealed. The maximum degree of sorption of iron cations in concentrated sulfuric acid is achieved in 10–15 min and makes up 95% and that of copper 30.6%. The process of iron sorption from sulfuric acid occurs according to the types of ion isomorphism and ion exchange, as indicated by a very high number of sorbed Fe ions and the absence of their release (desorption) from the zeolite into the solution. The Cu cations are sorbed by zeolite from acid by the ion exchange method, which is confirmed by the physicochemical analysis methods. Full article
(This article belongs to the Special Issue Adsorption Capabilities of Porous Materials)
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22 pages, 6369 KiB  
Article
Impact of Calcination Temperature on the Properties and Photocatalytic Efficiency of Cd0.6Mg0.2Cu0.2Fe2O4 Spinel Ferrites Synthesized via the Sol–Gel Method
by Abd Raouf Jdidi, Wided Nouira, Ahmed Selmi, Nidhal Drissi, Mohamed Aissa, Sobhi Hcini and Malek Gassoumi
Crystals 2025, 15(5), 457; https://doi.org/10.3390/cryst15050457 - 13 May 2025
Cited by 2 | Viewed by 579
Abstract
This study investigates the influence of calcination temperature on the structural, morphological, and optical properties of Cd0.6Mg0.2Cu0.2Fe2O4 spinel ferrites synthesized via the sol–gel method. By varying the calcination temperatures (950 °C and 1050 °C), [...] Read more.
This study investigates the influence of calcination temperature on the structural, morphological, and optical properties of Cd0.6Mg0.2Cu0.2Fe2O4 spinel ferrites synthesized via the sol–gel method. By varying the calcination temperatures (950 °C and 1050 °C), we analyze changes in crystallinity, cation distribution, and energy band gap using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV–visible spectroscopy. The results indicate that increasing calcination temperature enhances crystallinity and increases particle size while reducing the optical band gap energy. XPS analysis confirms shifts in cation site occupancy and an increase in oxygen vacancies at higher temperatures, which are crucial for charge carrier dynamics. Photocatalytic performance, evaluated through methylene blue degradation under UV light, improves with increasing calcination temperature due to enhanced charge separation and reduced recombination. These findings underscore the critical role of calcination temperature in optimizing spinel ferrites for environmental applications, particularly in wastewater treatment. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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19 pages, 5224 KiB  
Article
Effect of Metal Oxides on the Pyrolytic Behavior and Combustion Performance of 5-Aminotetrazole/Sodium Periodate Gas Generators in Atmospheric Environment
by Chengkuan Shi, Zefeng Guo, Bohuai Zhou, Yichao Liu, Jun Huang and Hua Guan
Materials 2025, 18(10), 2249; https://doi.org/10.3390/ma18102249 - 13 May 2025
Viewed by 371
Abstract
5-aminotetrazole (5AT)-based gas generators, particularly the 5AT/NaIO4 system, have garnered interest for their high gas production and energy potential. This study investigates the impact of various metal oxides (MnO2, Al2O3, TiO2, CuO, Fe2 [...] Read more.
5-aminotetrazole (5AT)-based gas generators, particularly the 5AT/NaIO4 system, have garnered interest for their high gas production and energy potential. This study investigates the impact of various metal oxides (MnO2, Al2O3, TiO2, CuO, Fe2O3, MgO, ZnO, and MoO3) on the thermal decomposition and combustion performance of 5AT/NaIO4. The REAL calculation program was used to infer reaction products, which indicated that the gas products are almost all harmless, with negligibly low percentages of NO and CO. Thermogravimetric analysis revealed that metal oxides, especially MoO3, significantly advance the decomposition process above 400 °C, reducing the activation energy by 130 kJ/mol and lowering critical ignition and thermal explosion temperatures. Combustion performance tests and closed bomb tests confirmed MoO3’s positive effect, accelerating reaction rates and enhancing decomposition efficiency. The system’s high Gibbs free energy indicates non-spontaneous reactions. These findings provide valuable insights for designing environmentally friendly gas generators, highlighting MoO3’s potential as an effective catalyst. Full article
(This article belongs to the Section Materials Physics)
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14 pages, 12484 KiB  
Article
Comparative Study on the Catalytic Ozonation of Biotreated Landfill Leachate Using γ-Al2O3-Based Catalysts Loaded with Different Metals
by Jiancheng Li, Liya Fu, Yin Yu, Yue Yuan, Hongbo Xi and Changyong Wu
Sustainability 2025, 17(10), 4376; https://doi.org/10.3390/su17104376 - 12 May 2025
Viewed by 402
Abstract
Global municipal solid waste (~2B tons/year) affects sustainability, as landfill and incineration face persistent leachate contamination, demanding effective management to advance water recycling and circular economies. Accelerated investigation of hybrid biocatalytic ozonation systems is imperative to enhance contaminant removal efficiency for stringent discharge [...] Read more.
Global municipal solid waste (~2B tons/year) affects sustainability, as landfill and incineration face persistent leachate contamination, demanding effective management to advance water recycling and circular economies. Accelerated investigation of hybrid biocatalytic ozonation systems is imperative to enhance contaminant removal efficiency for stringent discharge compliance. This study investigates the catalytic ozonation effects of γ-Al2O3-based catalysts loaded with different metals (Cu, Mn, Zn, Y, Ce, Fe, Mg) on the biochemical effluent of landfill leachate. The catalysts were synthesized via a mixed method and subsequently characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Pseudo-second-order kinetics revealed active metal loading’s impact on adsorption capacity, with Cu/γ-Al2O3 and Mg/γ-Al2O3 achieving the highest Qe (0.85). To elucidate differential degradation performance among the catalysts, the ozone/oxygen gas mixture was introduced at a controlled flow rate. Experimental results demonstrate that the Cu/γ-Al2O3 catalyst, exhibiting optimal comprehensive degradation performance, achieved COD and TOC removal efficiencies of 84.5% and 70.9%, respectively. UV–vis absorbance ratios revealed the following catalytic disparities: Mg/γ-Al2O3 achieved the highest aromatic compound removal efficiency; Ce/γ-Al2O3 excelled in macromolecular organics degradation. EEM-PARAFAC analysis revealed differential fluorophore removal: Cu/γ-Al2O3 exhibited broad efficacy across all five components, while Mg/γ-Al2O3 demonstrated optimal removal of C2 and C4, but showed limited efficacy toward C5. These findings provide important insights into selecting catalysts in practical engineering applications for landfill leachate treatment. This study aims to elucidate catalyst formulation-dependent degradation disparities, guiding water quality-specific catalyst selection to ultimately enhance catalytic ozonation efficiency. Full article
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