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Physicochemical Properties of Supramolecular Complexes Formed Between Cyclodextrin and Rice Bran-Derived Komecosanol
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Monte Carlo Investigation of Orientation-Dependent Percolation Networks in Carbon Nanotube-Based Conductive Polymer Composites
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Improving Oxidation Stability and Insulation Performance of Plant-Based Oils for Sustainable Power Transformers
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Theoretical Insights into the Chemical Bonding, Electronic Structure, and Spectroscopic Properties of the Lanarkite Pb2SO5 Structure
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Reversible Thermochemical Routes for Carbon Neutrality: A Review of CO2 Methanation and Steam Methane Reforming
Journal Description
Physchem
Physchem
is an international, peer-reviewed, open access journal on science and technology in physical chemistry published quarterly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, ESCI (Web of Science) and other databases.
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 24.3 days after submission; acceptance to publication is undertaken in 3.3 days (median values for papers published in this journal in the first half of 2025).
- Recognition of Reviewers: APC discount vouchers, optional signed peer review, and reviewer names published annually in the journal.
Impact Factor:
1.7 (2024);
5-Year Impact Factor:
1.6 (2024)
Latest Articles
Effect of Vibration on Open-Cathode Direct Methanol Fuel Cell Stack Performance
Physchem 2025, 5(4), 44; https://doi.org/10.3390/physchem5040044 - 8 Oct 2025
Abstract
This study investigates the impact of vibration frequency on the performance of a 10-cell open-cathode direct methanol fuel cell (OC-DMFC) stack. Experiments were conducted using three different vibration frequencies (15, 30, and 60 Hz) and compared against a baseline condition without vibration. Performance
[...] Read more.
This study investigates the impact of vibration frequency on the performance of a 10-cell open-cathode direct methanol fuel cell (OC-DMFC) stack. Experiments were conducted using three different vibration frequencies (15, 30, and 60 Hz) and compared against a baseline condition without vibration. Performance was evaluated under varying methanol–water fuel flow rates (1, 5, 25, and 50 mL·min−1) while maintaining constant operating conditions: methanol temperature at 70 °C, methanol concentration at 1 M, and cathode air flow velocity at 4.8 m·s−1. The optimal performance was observed at a fuel flow rate of 5 mL·min−1, where the maximum power density reached 26.05 mW·cm−2 under 15 Hz vibration—representing a 14% increase compared to the non-vibrated condition. These findings demonstrate that low-frequency vibration can enhance fuel cell performance by improving mass transport characteristics.
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(This article belongs to the Section Electrochemistry)
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Controlled Hydrophilic–Hydrophobic Transition of PET Films via Fluorination and Drying
by
Zhipeng He, Jae-Ho Kim and Susumu Yonezawa
Physchem 2025, 5(4), 43; https://doi.org/10.3390/physchem5040043 - 7 Oct 2025
Abstract
Polyethylene terephthalate (PET) films were modified by direct fluorination using fluorine gas at room temperature and 660 torr for reaction times ranging from 10 min to 5 h. Some of the fluorinated samples were dried at 70 °C for 7 days. FT-IR and
[...] Read more.
Polyethylene terephthalate (PET) films were modified by direct fluorination using fluorine gas at room temperature and 660 torr for reaction times ranging from 10 min to 5 h. Some of the fluorinated samples were dried at 70 °C for 7 days. FT-IR and XPS analyses confirmed the successful incorporation of fluorine into the PET structure, with the formation of -CHF- and -CF2- groups. The degree of fluorination increased with the reaction time, but excessive reaction led to the formation and loss of CF4. Drying further decreased the fluorine content due to the continued CF4 formation. XRD revealed that fluorination increased the crystallinity of PET owing to increased polarity, whereas drying decreased the crystallinity owing to increased crosslinking. The DSC results showed an increase in the glass transition temperature (Tg) after fluorination and drying, which was attributed to increased polarity and crosslinking, respectively. The surface hydrophilicity of PET increased significantly with fluorination time, and the water contact angle decreased to as low as 3.35°. This was due to the introduction of polar fluorine atoms and the development of a rough and porous surface morphology, as observed by AFM. Interestingly, drying of the fluorinated samples led to an increase in the water contact angle, with a maximum of 85.95°, owing to increased crosslinking and particle formation on the surface. This study demonstrates a simple and effective method for controlling the hydrophilicity and hydrophobicity of PET surfaces via direct fluorination and drying.
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(This article belongs to the Section Surface Science)
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Top-Down Ultrasonication Method for ZnO Nanoparticles Fabrication and Their Application in Developing Pectin-Glycerol Bionanocomposite Films
by
Maulida Nur Astriyani, Nugraha Edhi Suyatma, Vallerina Armetha, Eko Hari Purnomo, Tjahja Muhandri, Faleh Setia Budi, Boussad Abbes and Ahmed Tara
Physchem 2025, 5(4), 42; https://doi.org/10.3390/physchem5040042 - 3 Oct 2025
Abstract
Ultrasonication offers a safer, lower-temperature method for synthesizing zinc oxide nanoparticles (ZnO-NPs). This study details the development of a pectin-glycerol bionanocomposite film reinforced with ZnO-NPs produced using the top-down ultrasonication method. ZnO-NPs were fabricated with varying ultrasonication durations (0, 30, and 60 min)
[...] Read more.
Ultrasonication offers a safer, lower-temperature method for synthesizing zinc oxide nanoparticles (ZnO-NPs). This study details the development of a pectin-glycerol bionanocomposite film reinforced with ZnO-NPs produced using the top-down ultrasonication method. ZnO-NPs were fabricated with varying ultrasonication durations (0, 30, and 60 min) and the addition of pectin as a capping agent. Extended ultrasonication duration resulted in smaller particle size and more defined morphology. Bionanocomposite films were prepared using the solvent casting method by incorporating ZnO-NPs (0, 0.5, 1, 2.5% w/w) and glycerol (0, 10, 20% w/w) as a plasticizer to a pectin base. The inclusion of ZnO-NPs and glycerol did not affect the shear-thinning behavior of the film-forming solution. FTIR analysis indicated interactions between ZnO-NPs, glycerol, and pectin. The addition of ZnO-NPs and glycerol reduced tensile strength but increased flexibility. ZnO-NPs improved barrier and thermal properties by reducing water vapor permeability and increasing melting point, whereas glycerol lowered glass transition temperature, thus enhancing film flexibility. The best film performance was observed with a combination of 0.5% ZnO and 20% glycerol. These results highlight the effectiveness of the top-down ultrasonication method as a sustainable approach for ZnO-NPs fabrication, supporting the development of pectin/ZnO-NPs/glycerol films as a promising material for eco-friendly packaging.
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(This article belongs to the Section Nanoscience)
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Open AccessArticle
Predicting the Bandgap of Graphene Based on Machine Learning
by
Qinze Yu, Lingtao Zhan, Xiongbai Cao, Tingting Wang, Haolong Fan, Zhenru Zhou, Huixia Yang, Teng Zhang, Quanzhen Zhang and Yeliang Wang
Physchem 2025, 5(4), 41; https://doi.org/10.3390/physchem5040041 - 1 Oct 2025
Abstract
Over the past decade, two-dimensional materials have become a research hotspot in chemistry, physics, materials science, and electrical and optical engineering due to their excellent properties. Graphene is one of the earliest discovered 2D materials. The absence of a bandgap in pure graphene
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Over the past decade, two-dimensional materials have become a research hotspot in chemistry, physics, materials science, and electrical and optical engineering due to their excellent properties. Graphene is one of the earliest discovered 2D materials. The absence of a bandgap in pure graphene limits its application in digital electronics where switching behavior is essential. In the present study, researchers have proposed a variety of methods for tuning the graphene bandgap. Machine learning methodologies have demonstrated the capability to enhance the efficiency of materials research by automating the recording of characteristic parameters from the discovery and preparation of 2D materials, property calculations, and simulations, as well as by facilitating the extraction and summarization of governing principles. In this work, we use first principle calculations to build a dataset of graphene band gaps under various conditions, including the application of a perpendicular external electric field, nitrogen doping, and hydrogen atom adsorption. Support Vector Machine (SVM), Random Forest (RF), and Multi-Layer Perceptron (MLP) Regression were utilized to successfully predict the graphene bandgap, and the accuracy of the models was verified using first principles. Finally, the advantages and limitations of the three models were compared.
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(This article belongs to the Section Application of New Technologies: Artificial Intelligence, Virtual Reality, Quantum Computing and Machine Learning)
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Open AccessArticle
Viscosity Analysis of Electron-Beam Degraded Gellan in Dilute Aqueous Solution
by
Fathi Elashhab, Lobna Sheha, Nada Elzawi and Abdelsallam E. A. Youssef
Physchem 2025, 5(4), 40; https://doi.org/10.3390/physchem5040040 - 30 Sep 2025
Abstract
Gellan gum (Gellan), a versatile polysaccharide applied in gel formation and prebiotic formulations, is often processed to tailor its molecular properties. Previous studies employed gamma irradiation and chemical hydrolysis, though without addressing systematic scaling behavior. This study investigates the structural and conformational modifications
[...] Read more.
Gellan gum (Gellan), a versatile polysaccharide applied in gel formation and prebiotic formulations, is often processed to tailor its molecular properties. Previous studies employed gamma irradiation and chemical hydrolysis, though without addressing systematic scaling behavior. This study investigates the structural and conformational modifications of Gellan in dilute aqueous salt solutions using a safer and eco-friendly approach: atmospheric low-dose electron beam (e-beam) degradation coupled with viscosity analysis. Native and E-beam-treated Gellan samples (0.05 g/cm3 in 0.1 M KCl) were examined by relative viscosity at varying temperatures, with intrinsic viscosity and molar mass determined via Solomon–Ciuta and Mark–Houwink relations. Molar mass degradation followed first-order kinetics, yielding rate constants and degradation lifetimes. Structural parameters, including radius of gyration and second virial coefficient, produced scaling coefficients of 0.62 and 0.15, consistent with perturbed coil conformations in a good solvent. The shape factor confirmed preservation of an ideal random coil structure despite irradiation. Conformational flexibility was further analyzed using theoretical models. Transition state theory (TST) revealed that e-beam radiation lowered molar mass and activation energy but raised activation entropy, implying reduced flexibility alongside enhanced solvent interactions. The freely rotating chain (FRC) model estimated end-to-end distance (Rθ) and characteristic ratio (C∞), while the worm-like chain (WLC) model quantified persistence length (lp). Results indicated decreased Rθ, increased lp, and largely unchanged C∞, suggesting diminished chain flexibility without significant deviation from ideal coil behavior. Overall, this work provides new insights into Gellan’s scaling laws and flexibility under aerobic low-dose E-beam irradiation, with relevance for bioactive polysaccharide applications.
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(This article belongs to the Section Theoretical and Computational Chemistry)
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Open AccessArticle
Experimental Thermal Analysis of Box-Type Shell-and-Tube Configuration Filled with RT42 Phase Change Material: A Case Study
by
Ihsan Ur Rahman, Numan Khan, Oronzio Manca, Bernardo Buonomo and Sergio Nardini
Physchem 2025, 5(4), 39; https://doi.org/10.3390/physchem5040039 - 28 Sep 2025
Abstract
Thermal management in heat exchangers is crucial in many industrial, medical, and scientific applications. However, reducing dependency on active energy sources still represents a substantial challenge. In this context, phase change materials (PCMs) offer an effective solution due to their ability to store
[...] Read more.
Thermal management in heat exchangers is crucial in many industrial, medical, and scientific applications. However, reducing dependency on active energy sources still represents a substantial challenge. In this context, phase change materials (PCMs) offer an effective solution due to their ability to store and release large amounts of latent heat, assisting in passive thermal management. Therefore, this study proposes the use of RT42 PCM inside a box-type shell-and-tube configuration to establish the relationship between flow rate and charging and discharging behavior of PCM. In the proposed system, heat transferring fluid (HTF) water is circulated in the internal tubes at 60 °C, where the temperature is monitored by a series of thermocouples strategically placed inside the box-type configuration. To evaluate the effect of the flow of HTF on the thermal behavior of the PCM, the charging (melting) and discharging (solidification) analysis is performed by varying the water flow rate at three levels: 1.2, 0.8, and 0.4 L/min inside the laminar region (Re < 2300). A thermal camera and two webcams were used to assess the surface temperature distribution and PCM response, respectively. It was determined that increasing the flow rate accelerates charging and discharging with fluctuations in temperature curves during melting.
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(This article belongs to the Section Kinetics and Thermodynamics)
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Open AccessArticle
Effect of Organic Acid Mixtures on the Extraction Efficiency, Physicochemical, and Thermal Properties of Pigskin Gelatin and Resulting Films
by
Diego Ezequiel Velazquez and María Emilia Latorre
Physchem 2025, 5(3), 38; https://doi.org/10.3390/physchem5030038 - 11 Sep 2025
Abstract
Animal tissue by-products, rich in collagen, represent a valuable source of biomaterials. Understanding their physicochemical and thermal behavior is essential for expanding their applications. In this study, pigskin gelatin was extracted through acid hydrolysis using a combination of acetic acid (AH) and either
[...] Read more.
Animal tissue by-products, rich in collagen, represent a valuable source of biomaterials. Understanding their physicochemical and thermal behavior is essential for expanding their applications. In this study, pigskin gelatin was extracted through acid hydrolysis using a combination of acetic acid (AH) and either lactic, citric, or ascorbic acid (75:25, v:v, [0.5 M]), followed by thermal denaturation. We evaluated the physicochemical properties of the gelatin solutions (pH, hydroxyproline content, and extraction yield), as well as the macroscopic gel characteristics. Gelatin films were then prepared and analyzed for moisture content, color, and thermal properties. One-way ANOVA was applied to compare treatments, and Pearson’s correlation was used to assess the relationship between the solution pH and physicochemical parameters. Significant differences in the final pH of the solutions were observed among the acid mixture treatments, though the hydroxyproline content and extraction yield were not significantly affected. All gelatin solutions formed stable gels, and the resulting films exhibited similar moisture content. Thermal analysis revealed treatment-dependent variations. Specifically, a significant negative correlation (p < 0.005) was found between the gelatin solution pH and the melting temperature. These results suggest that the use of organic acid mixtures can effectively modulate gelatin properties, offering a versatile approach for tailoring biomaterials for both food and non-food applications.
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(This article belongs to the Section Biophysical Chemistry)
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Open AccessArticle
Improving Methanol Production from Carbon Dioxide Through Electrochemical Processes with Draining System
by
Cristina Rincón and Carlos Armenta-Déu
Physchem 2025, 5(3), 37; https://doi.org/10.3390/physchem5030037 - 9 Sep 2025
Abstract
The paper describes the conversion of carbon dioxide into methanol in a chemical reactor under standard operating conditions. Electro-analytical techniques, cyclic voltammetry, and chrono-amperometry characterize the process. The electrochemical redox reaction develops using various catalyzers to evaluate the performance of the carbon dioxide
[...] Read more.
The paper describes the conversion of carbon dioxide into methanol in a chemical reactor under standard operating conditions. Electro-analytical techniques, cyclic voltammetry, and chrono-amperometry characterize the process. The electrochemical redox reaction develops using various catalyzers to evaluate the performance of the carbon dioxide conversion into methanol process under variable chemical conditions. The results of the applied technique showed an incomplete redox reaction with an electronic change of z = 2.84 on average, below the ideal number, z = 6, that may be due to methanol decomposition (reverse reaction) because the system operates with a reaction constant above the equilibrium value. The methanol production may improve by draining the methanol/water solution from the chemical reactor to reduce the methanol concentration in the electrochemical cell, shifting the forward reaction towards the formation of methanol, increasing the electron change number, which approaches the ideal value, and improving the methanol production efficiency. The draining process shows a significant increase in methanol formation, which depends on the draining flow rate and the catalyzer type. A simulation process shows that if we operate in optimum conditions, with no methanol decomposition through a reverse reaction, the redox reaction fulfills the ideal condition of maximum electronic change. The experimental tests validate the simulation results, showing a relevant increase in the electron change number with values up to z = 4.2 for optimum draining flow rate conditions (0.2 L/s). The experimental results show a relative increase factor of 4.7 in methanol production, meaning we can produce more than four times more methanol compared with no draining techniques. The data analysis shows that the draining flow rate has a threshold of 0.2 L/s, beyond which the extent of the reaction reverses, reducing the methanol formation due to a chemical reaction disequilibrium. The paper concludes that using the draining method, the methanol production mass rate increases significantly from an average value of 20.9 kg/h for non-draining use, considering all catalyzer types, to a range between 91.9 kg/h and 104.3 kg/h, depending on the flow rate. Averaging all values for different flow rates and comparing with the non-draining case, we obtain an absolute methanol production mass rate of 77 kg/h, meaning an incremental percentage of 469.1%, more than four times the initial production. Although the proposed methodology looks promising, applying this procedure on an industrial scale may suffer from restrictions since the chemical reactions intervening in the methanol formation do not perform linearly. According to experimental tests, the best option among the six catalyzers used for methanol production is the plain copper, with copper oxides (Cu2O, CuO) and copper Sulphur (CuS) as feasible alternatives.
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(This article belongs to the Section Electrochemistry)
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A Comprehensive Solution and Solid-State NMR Study of Proton Spin Lattice Relaxation in Paramagnetic Metallocenes
by
Gabrielle E. Harmon-Welch, Douglas W. Elliott, Nattamai Bhuvanesh, Vladimir I. Bakhmutov and Janet Blümel
Physchem 2025, 5(3), 36; https://doi.org/10.3390/physchem5030036 - 5 Sep 2025
Abstract
Solid solutions of the metallocenes ferrocene (Cp2Fe), nickelocene (Cp2Ni), and cobaltocene (Cp2Co) have been prepared by manually grinding the components together, or by co-crystallizing them from solution. In the solid solutions Cp2Fe/Cp2Ni and
[...] Read more.
Solid solutions of the metallocenes ferrocene (Cp2Fe), nickelocene (Cp2Ni), and cobaltocene (Cp2Co) have been prepared by manually grinding the components together, or by co-crystallizing them from solution. In the solid solutions Cp2Fe/Cp2Ni and Cp2Co/Cp2Ni, the cyclopentadienyl (Cp) protons relax via dipolar electron–proton interactions, which represent the dominant relaxation mechanism. The 1H T1 relaxation times of the molecules Cp2Ni and Cp2Co, dissolved in CDCl3, and in the solid solutions, show that the relaxation takes place intramolecularly. The relaxation of the protons is propagated exclusively via the unpaired electrons of the metal centers to which their Cp rings are coordinated, due to the large intermolecular distances that are greater than 3.91 Å. In contrast, the intramolecular distances between the electrons of the metal atoms and the protons of their coordinated Cp rings are merely 2.70 Å. Using these intramolecular distances and the 1H T1 relaxation times, the electron relaxation times T1e have been determined as 17 × 10−13 s in CDCl3 solutions and 45 × 10−13 s in the solid state for Cp2Ni. The corresponding T1e times for Cp2Co are calculated as ca. 5 × 10−13 s and 20 × 10−13 s. Grinding Cp2Fe and Cp2Ni together leads to two different 1H T1 relaxation times for the protons of Cp2Fe. The longer T1 relaxation time indicates domains that consist mostly of Cp2Fe molecules. The short T1 times show a close contact of Cp2Fe and Cp2Ni molecules. An analysis of the short 1H T1 times reveals the presence of at least two to three short distances of 3.91 Å between Cp2Fe and Cp2Ni molecules. These results support the hypothesis that dry grinding of the metallocenes Cp2Fe and Cp2Ni in ratios that were changed in 10% increments from 90%/10% to 30%/70% leads to domains that mostly consist of Cp2Fe molecules, and additionally to domains that contain a mixture of the components on the molecular level.
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(This article belongs to the Section Solid-State Chemistry and Physics)
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Increasing the Probability of Obtaining Intergrown Mixtures of Nanostructured Manganese Oxide Phases Under Solvothermal Conditions by Mixing Additives with Weak and Strong Chelating Natures
by
María Lizbeth Barrios-Reyna, Enrique Sánchez-Mora and Enrique Quiroga-González
Physchem 2025, 5(3), 35; https://doi.org/10.3390/physchem5030035 - 16 Aug 2025
Abstract
Intergrown mixtures of nanostructured manganese oxide phases have been obtained using a highly complexing agent (ethylenediamine) and a weak complexer (urea) during their solvothermal synthesis. In this work, through a detailed structural analysis, it is evidenced the formation of an intergrown mixture of
[...] Read more.
Intergrown mixtures of nanostructured manganese oxide phases have been obtained using a highly complexing agent (ethylenediamine) and a weak complexer (urea) during their solvothermal synthesis. In this work, through a detailed structural analysis, it is evidenced the formation of an intergrown mixture of three distinct manganese oxide phases (β-MnO2, α-Mn2O3, and Mn3O4). Scanning electron microscopy shows that the products have just one morphology, indicating that the different manganese oxide phases may have grown together, organizing themselves in a 3D crystal network. The reaction mechanisms are discussed in this paper. It is of great interest to produce intergrown mixtures of manganese oxide phases to take advantage of the availability of the different oxidation states of Mn in neighboring crystallites for applications like catalysis.
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(This article belongs to the Section Solid-State Chemistry and Physics)
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Physicochemical Properties of Supramolecular Complexes Formed Between Cyclodextrin and Rice Bran-Derived Komecosanol
by
Mione Uchimura, Akiteru Ohtsu, Junki Tomita, Yoshiyuki Ishida, Daisuke Nakata, Keiji Terao and Yutaka Inoue
Physchem 2025, 5(3), 34; https://doi.org/10.3390/physchem5030034 - 13 Aug 2025
Abstract
In this study, supramolecular inclusion complexes composed of komecosanol (Ko), a lipophilic compound derived from rice bran, and α-cyclodextrin (αCD) were prepared using a solvent-free three-dimensional (3D) ball milling method. Their physicochemical properties were examined using various techniques. Powder X-ray diffraction analysis of
[...] Read more.
In this study, supramolecular inclusion complexes composed of komecosanol (Ko), a lipophilic compound derived from rice bran, and α-cyclodextrin (αCD) were prepared using a solvent-free three-dimensional (3D) ball milling method. Their physicochemical properties were examined using various techniques. Powder X-ray diffraction analysis of the ground mixture at a Ko/αCD ratio of 1/8 revealed the disappearance of diffraction peaks characteristic of Ko and the emergence of new peaks, indicating the formation of a distinct crystalline phase. Moreover, differential scanning calorimetry analysis showed the disappearance of the endothermic peaks corresponding to Ko, indicating molecular-level interactions with αCD. Near-infrared spectroscopy results suggested the formation of hydrogen bonds between the C–H groups of Ko and the O–H groups of αCD. Solid-state 13C CP/MAS NMR and T1 relaxation time measurements indicated the formation of a pseudopolyrotaxane structure, while scanning electron microscopy images confirmed distinct morphological changes consistent with complex formation. These findings demonstrate that 3D ball milling facilitates the formation of Ko/αCD inclusion complexes with a supramolecular architecture, providing a novel approach to improve the formulation and bioavailability of poorly water-soluble lipophilic compounds.
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(This article belongs to the Section Biophysical Chemistry)
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Green Synthesis and Characterization of Fe3O4 and ε-Fe2O3 Nanoparticles Using Apricot Kernel Shell Extract and Study of Their Optical Properties
by
Tayeb Ben Kouider, Lahcene Souli, Yazid Derouiche, Taoufik Soltani and Ulrich Maschke
Physchem 2025, 5(3), 33; https://doi.org/10.3390/physchem5030033 - 10 Aug 2025
Abstract
The synthesis of Fe3O4 and ε-Fe2O3 nanoparticles (hereafter referred to as Fe3O4 NPs and ε-Fe2O3 NPs, respectively) was conducted in an eco-friendly manner using FeCl3·6H2O as the
[...] Read more.
The synthesis of Fe3O4 and ε-Fe2O3 nanoparticles (hereafter referred to as Fe3O4 NPs and ε-Fe2O3 NPs, respectively) was conducted in an eco-friendly manner using FeCl3·6H2O as the primary reactant. The experiment was conducted by subjecting the sample to an aqueous solution of FeCl2·4H2O at a temperature of 80 °C for a duration of 45 min, with the inclusion of apricot kernel shell extract (AKSE) as a natural reducing agent. The synthesized Fe3O4 NPs and ε-Fe2O3 NPs were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The optical properties of Fe3O4 NPs and ε-Fe2O3 NPs were examined, with the band gap energy estimated using the Kubelka–Munk formula. The results demonstrated a band gap of Eg (Fe3O4 NPs) = 2.59 eV and Eg (ε-Fe2O3 NPs) = 2.75 eV, thereby confirming their semiconductor behavior. The photoconductivity of Fe3O4 NPs and ε-Fe2O3 NPs was analyzed as a function of photon energy. For Fe3O4 NPs, photoconductivity exhibited an increase between 1.37 eV and 6.2 eV prior to reaching a state of stability. A comparable trend was observed for ε-Fe2O3 NPs, with an increase from 1.35 eV to 6.22 eV, followed by stabilization. Furthermore, the extinction coefficient (k) was determined. For Fe3O4 NPs, k ranged from 39 to a maximum of 300, while for ε-Fe2O3 NPs, it varied from 37 to a maximum of 280. A higher k value indicates strong light absorption, rendering these nanoparticles highly suitable for photothermal and sensing applications.
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(This article belongs to the Section Photophysics, Photochemistry and Photobiology)
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Pectin Extraction from Citrus Waste: Structural Quality and Yield with Mineral and Organic Acids
by
Muhamad Hawari Mansor, Lydia Williamson, Daniel Ludwikowski, Faith Howard and Munitta Muthana
Physchem 2025, 5(3), 32; https://doi.org/10.3390/physchem5030032 - 10 Aug 2025
Abstract
Pectin is a renewable polysaccharide valued for its gelling, stabilising, and encapsulating properties, with broad applications in food, pharmaceutical, and industrial sectors. However, extraction conditions critically affect its yield, structural integrity, and functional performance. Despite citrus peel being a major source of pectin,
[...] Read more.
Pectin is a renewable polysaccharide valued for its gelling, stabilising, and encapsulating properties, with broad applications in food, pharmaceutical, and industrial sectors. However, extraction conditions critically affect its yield, structural integrity, and functional performance. Despite citrus peel being a major source of pectin, large amounts remain underutilised as waste. This study systematically investigates how different acid types influence the extraction efficiency and structural quality of pectin derived from citrus peel. Dried citrus peel powder was extracted using four acids—sulphuric, hydrochloric, acetic, and citric—under controlled conditions at 80 °C. Extractions were performed at a fixed time of 90 min for all acids, with additional time trials for sulphuric acid. Extracted pectins were evaluated for gravimetric yield, colour, solubility, degree of esterification (DE) by titration and FTIR, and structural features using FTIR and 1H NMR spectroscopy. Results showed that sulphuric and hydrochloric acids yielded the highest pectin recoveries (30–35% and 20–25%, respectively) but caused significant degradation, evident from dark colour, broad FTIR peaks, low DE (<10%), and poor solubility. In contrast, acetic and citric acid extractions resulted in moderate yields (8–15%) but preserved the pectin backbone and maintained higher DE (>30%) compared to the mineral acid-extracted samples and the commercial low methoxyl (LM) standard, as confirmed by clear FTIR and NMR profiles. These findings demonstrate the trade-off between extraction yield and structural integrity, underscoring the potential of mild organic acids to produce high-quality pectin suitable for value-added applications. Optimising acid type and extraction conditions can support sustainable waste valorisation and expand the industrial use of citrus-derived pectin.
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(This article belongs to the Section Biophysical Chemistry)
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Influence of Molecular Weight of Anthraquinone Acid Dyes on Color Strength, Migration, and UV Protection of Polyamide 6 Fabrics
by
Nawshin Farzana, Abu Naser Md Ahsanul Haque, Shamima Akter Smriti, Abu Sadat Muhammad Sayem, Fahmida Siddiqa, Md Azharul Islam, Md Nasim and S M Kamrul Hasan
Physchem 2025, 5(3), 31; https://doi.org/10.3390/physchem5030031 - 4 Aug 2025
Abstract
Anthraquinone acid dyes are widely used in dyeing polyamide due to their good exhaustion and brightness. While ionic interactions primarily govern dye–fiber bonding, the molecular weight (Mw) of these dyes can significantly influence migration, apparent color strength, and fastness behavior. This study offers
[...] Read more.
Anthraquinone acid dyes are widely used in dyeing polyamide due to their good exhaustion and brightness. While ionic interactions primarily govern dye–fiber bonding, the molecular weight (Mw) of these dyes can significantly influence migration, apparent color strength, and fastness behavior. This study offers comparative insight into how the Mw of structurally similar anthraquinone acid dyes impacts their diffusion, fixation, and functional outcomes (e.g., UV protection) on polyamide 6 fabric, using Acid Blue 260 (Mw~564) and Acid Blue 127:1 (Mw~845) as representative low- and high-Mw dyes. The effects of dye concentration, pH, and temperature on color strength (K/S) were evaluated, migration index and zeta potential were measured, and UV protection factor (UPF) and FTIR analyses were used to assess fabric functionality. Results showed that the lower-Mw dye exhibited higher migration tendency, particularly at increased dye concentrations, while the higher-Mw dye demonstrated greater color strength and superior wash fastness. Additionally, improved UPF ratings were associated with higher-Mw dye due to enhanced light absorption. These findings offer practical insights for optimizing acid dye selection in polyamide coloration to balance color performance and functional attributes.
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(This article belongs to the Section Surface Science)
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Open AccessCommunication
Scalable Synthesis of 2D TiNCl via Flash Joule Heating
by
Gabriel A. Silvestrin, Marco Andreoli, Edson P. Soares, Elita F. Urano de Carvalho, Almir Oliveira Neto and Rodrigo Fernando Brambilla de Souza
Physchem 2025, 5(3), 30; https://doi.org/10.3390/physchem5030030 - 28 Jul 2025
Abstract
A scalable synthesis of two-dimensional titanium nitride chloride (TiNCl) via flash Joule heating (FJH) using titanium tetrachloride (TiCl4) precursor has been developed. This single-step method overcomes traditional synthesis challenges, including high energy consumption, multi-step procedures, and hazardous reagent requirements. The structural
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A scalable synthesis of two-dimensional titanium nitride chloride (TiNCl) via flash Joule heating (FJH) using titanium tetrachloride (TiCl4) precursor has been developed. This single-step method overcomes traditional synthesis challenges, including high energy consumption, multi-step procedures, and hazardous reagent requirements. The structural and chemical properties of the synthesized TiNCl were characterized through multiple analytical techniques. X-ray diffraction (XRD) patterns confirmed the presence of TiNCl phase, while Raman spectroscopy data showed no detectable oxide impurities. Fourier transform infrared spectroscopy (FTIR) analysis revealed characteristic Ti–N stretching vibrations, further confirming successful titanium nitride synthesis. Transmission electron microscopy (TEM) imaging revealed thin, plate-like nanostructures with high electron transparency. These analyses confirmed the formation of highly crystalline TiNCl flakes with nanoscale dimensions and minimal structural defects. The material exhibits excellent structural integrity and phase purity, demonstrating potential for applications in photocatalysis, electronics, and energy storage. This work establishes FJH as a sustainable and scalable approach for producing MXenes with controlled properties, facilitating their integration into emerging technologies. Unlike conventional methods, FJH enables rapid, energy-efficient synthesis while maintaining material quality, providing a viable route for industrial-scale production of two-dimensional materials.
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(This article belongs to the Section Nanoscience)
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Open AccessReview
Reversible Thermochemical Routes for Carbon Neutrality: A Review of CO2 Methanation and Steam Methane Reforming
by
Marisa Martins, Carlos Andrade and Amadeu D. S. Borges
Physchem 2025, 5(3), 29; https://doi.org/10.3390/physchem5030029 - 23 Jul 2025
Abstract
This review explores CO2 methanation and steam methane reforming (SMR) as two key thermochemical processes governed by reversible reactions, each offering distinct contributions to carbon-neutral energy systems. The objective is to provide a comparative assessment of both processes, highlighting how reaction reversibility
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This review explores CO2 methanation and steam methane reforming (SMR) as two key thermochemical processes governed by reversible reactions, each offering distinct contributions to carbon-neutral energy systems. The objective is to provide a comparative assessment of both processes, highlighting how reaction reversibility can be strategically leveraged for decarbonization. The study addresses methane production via CO2 methanation and hydrogen production via SMR, focusing on their thermodynamic behaviors, catalytic systems, environmental impacts, and economic viability. CO2 methanation, when powered by renewable hydrogen, can result in emissions ranging from −471 to 1076 kg CO2-equivalent per MWh of methane produced, while hydrogen produced from SMR ranges from 90.9 to 750.75 kg CO2-equivalent per MWh. Despite SMR’s lower production costs (USD 21–69/MWh), its environmental footprint is considerably higher. In contrast, methanation offers environmental benefits but remains economically uncompetitive (EUR 93.53–204.62/MWh). Both processes rely primarily on Ni-based catalysts, though recent developments in Ru-based and bimetallic systems have demonstrated improved performance. The review also examines operational challenges such as carbon deposition and catalyst deactivation. By framing these technologies through the shared lens of reversibility, this work outlines pathways toward integrated, efficient, and circular energy systems aligned with long-term sustainability and climate neutrality goals.
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(This article belongs to the Section Kinetics and Thermodynamics)
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Open AccessReview
Depolymerization to Decontamination: Transforming PET Waste into Tailored MOFs for Advanced Pollutant Adsorption
by
Asma Nouira and Imene Bekri-Abbes
Physchem 2025, 5(3), 28; https://doi.org/10.3390/physchem5030028 - 19 Jul 2025
Abstract
Plastic waste and water pollution demand circular economy-driven innovations. This review examines metal–organic framework (MOF) synthesis from polyethylene terephthalate (PET) waste for wastewater treatment. Depolymerized PET yields terephthalic acid and ethylene glycol—essential MOF precursors. We evaluate the following: (1) PET depolymerization (hydrolysis, glycolysis,
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Plastic waste and water pollution demand circular economy-driven innovations. This review examines metal–organic framework (MOF) synthesis from polyethylene terephthalate (PET) waste for wastewater treatment. Depolymerized PET yields terephthalic acid and ethylene glycol—essential MOF precursors. We evaluate the following: (1) PET depolymerization (hydrolysis, glycolysis, ammonolysis) for monomer recovery efficiency; (2) MOF synthesis (solvothermal, microwave, mechanochemical) using PET-derived linkers; (3) performance in adsorbing heavy metals, dyes, and emerging contaminants. PET-based MOFs match or exceed commercial adsorbents in pollutant removal while lowering costs. Their tunable porosity and surface chemistry enhance selectivity and capacity. By converting waste plastics into functional materials, this strategy tackles dual challenges: diverting PET from landfills and purifying water. The review underscores the environmental and economic benefits of waste-sourced MOFs, proposing scalable routes for sustainable water remediation aligned with zero-waste goals.
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(This article belongs to the Section Surface Science)
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Open AccessArticle
Monte Carlo Investigation of Orientation-Dependent Percolation Networks in Carbon Nanotube-Based Conductive Polymer Composites
by
Sang-Un Kim and Joo-Yong Kim
Physchem 2025, 5(3), 27; https://doi.org/10.3390/physchem5030027 - 7 Jul 2025
Abstract
Conductive polymer composites (CPCs) filled with anisotropic materials such as carbon nanotubes (CNTs) exhibit electrical behavior governed by percolation through filler networks. While filler volume and shape are commonly studied, the influence of orientation and alignment remains underexplored. This study uses Monte Carlo
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Conductive polymer composites (CPCs) filled with anisotropic materials such as carbon nanotubes (CNTs) exhibit electrical behavior governed by percolation through filler networks. While filler volume and shape are commonly studied, the influence of orientation and alignment remains underexplored. This study uses Monte Carlo simulations to examine how the mean orientation angle and angular dispersion of CNTs affect conductive network formation. The results demonstrate that electrical connectivity is highly sensitive to orientation. Contrary to conventional assumptions, maximum connectivity occurred not at 45° but at around 55–60°. A Gaussian-based orientation probability function was proposed to model this behavior. Additionally, increased orientation dispersion enhanced conductivity in cases where alignment initially hindered connection, highlighting the dual role of alignment and randomness. These findings position orientation as a critical design parameter—beyond filler content or geometry—for engineering CPCs with optimized electrical performance. The framework provides guidance for processing strategies that control alignment and supports applications such as stretchable electronics, directional sensors, and multifunctional materials. Future research will incorporate full 3D orientation modeling to reflect complex manufacturing conditions.
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(This article belongs to the Section Statistical and Classical Mechanics)
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Open AccessArticle
Rotational vs. Vibrational Excitations in a Chemical Laser
by
José Daniel Sierra Murillo
Physchem 2025, 5(3), 26; https://doi.org/10.3390/physchem5030026 - 4 Jul 2025
Abstract
The research reviews and contrasts two studies based on the gas-phase reaction OH + D2(v, j). In these studies, Quasi-Classical Trajectory (QCT) calculations and the Gaussian Binning (GB) technique were used on the Wu–Schatz–Lendvay–Fang–Harding (WSLFH) potential energy surface. Large sample sizes
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The research reviews and contrasts two studies based on the gas-phase reaction OH + D2(v, j). In these studies, Quasi-Classical Trajectory (QCT) calculations and the Gaussian Binning (GB) technique were used on the Wu–Schatz–Lendvay–Fang–Harding (WSLFH) potential energy surface. Large sample sizes allow for precise energy state distribution analysis across translational, vibrational, and rotational components in the products. A key observation is the influence of the vibrational and rotational excitation of D2 on the total angular momentum (J′) of the HOD* product. This study reveals that increasing the vibrational level, vD2, significantly shifts P(J′) distributions toward higher values, broadening them due to increased isotropy. In contrast, increasing the rotational level, jD2, results in a smaller shift but introduces greater anisotropy, leading to a more selective distribution of J′ values. The dual Gaussian Binning selection—Vibrational-GB followed by Rotational-GB—further highlights a preference for either odd or even J′ values, depending on the specific excitation conditions. These findings have implications for the development of chemical lasers, as the excitation and emission properties of HOD* can be leveraged in the laser design. Future research aims to extend this study to a broader range of initial conditions, refining the understanding of reaction dynamics in controlled gas-phase environments.
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(This article belongs to the Section Application of Lasers to Physical Chemistry)
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A Comprehensive Review of the Development of Perovskite Oxide Anodes for Fossil Fuel-Based Solid Oxide Fuel Cells (SOFCs): Prospects and Challenges
by
Arash Yahyazadeh
Physchem 2025, 5(3), 25; https://doi.org/10.3390/physchem5030025 - 23 Jun 2025
Abstract
Solid oxide fuel cells (SOFCs) represent a pivotal technology in renewable energy due to their clean and efficient power generation capabilities. Their role in potential carbon mitigation enhances their viability. SOFCs can operate via a variety of alternative fuels, including hydrocarbons, alcohols, solid
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Solid oxide fuel cells (SOFCs) represent a pivotal technology in renewable energy due to their clean and efficient power generation capabilities. Their role in potential carbon mitigation enhances their viability. SOFCs can operate via a variety of alternative fuels, including hydrocarbons, alcohols, solid carbon, and ammonia. However, several solutions have been proposed to overcome various technical issues and to allow for stable operation in dry methane, without coking in the anode layer. To avoid coke formation thermodynamically, methane is typically reformed, contributing to an increased degradation rate through the addition of oxygen-containing gases into the fuel gas to increase the O/C ratio. The performance achieved by reforming catalytic materials, comprising active sites, supports, and electrochemical testing, significantly influences catalyst performance, showing relatively high open-circuit voltages and coking-resistance of the CH4 reforming catalysts. In the next step, the operating principles and thermodynamics of methane reforming are explored, including their traditional catalyst materials and their accompanying challenges. This work explores the components and functions of SOFCs, particularly focusing on anode materials such as perovskites, Ruddlesden–Popper oxides, and spinels, along with their structure–property relationships, including their ionic and electronic conductivity, thermal expansion coefficients, and acidity/basicity. Mechanistic and kinetic studies of common reforming processes, including steam reforming, partial oxidation, CO2 reforming, and the mixed steam and dry reforming of methane, are analyzed. Furthermore, this review examines catalyst deactivation mechanisms, specifically carbon and metal sulfide formation, and the performance of methane reforming and partial oxidation catalysts in SOFCs. Single-cell performance, including that of various perovskite and related oxides, activity/stability enhancement by infiltration, and the simulation and modeling of electrochemical performance, is discussed. This review also addresses research challenges in regards to methane reforming and partial oxidation within SOFCs, such as gas composition changes and large thermal gradients in stack systems. Finally, this review investigates the modeling of catalytic and non-catalytic processes using different dimension and segment simulations of steam methane reforming, presenting new engineering designs, material developments, and the latest knowledge to guide the development of and the driving force behind an oxygen concentration gradient through the external circuit to the cathode.
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(This article belongs to the Section Electrochemistry)
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