Nanomaterials

25 pages, 4500 KiB

Open AccessArticle

Cost-Effective Bimetallic Catalysts for Green H₂ Production in Anion Exchange Membrane Water Electrolyzers

by Sabrina Campagna Zignani, Marta Fazio, Mariarosaria Pascale, Chiara Alessandrello, Claudia Triolo, Maria Grazia Musolino and Saveria Santangelo

Nanomaterials 2025, 15(13), 1042; https://doi.org/10.3390/nano15131042 - 4 Jul 2025

Abstract

Green hydrogen production from water electrolysis (WE) is one of the most promising technologies to realize a decarbonized future and efficiently utilize intermittent renewable energy. Among the various WE technologies, the emerging anion exchange membrane (AEMWE) technology shows the greatest potential for producing [...] Read more.

Green hydrogen production from water electrolysis (WE) is one of the most promising technologies to realize a decarbonized future and efficiently utilize intermittent renewable energy. Among the various WE technologies, the emerging anion exchange membrane (AEMWE) technology shows the greatest potential for producing green hydrogen at a competitive price. To achieve this goal, simple methods for the large-scale synthesis of efficient and low-cost electrocatalysts are needed. This paper proposes a very simple and scalable process for the synthesis of nanostructured NiCo- and NiFe-based electrode materials for a zero-gap AEMWE full cell. For the preparation of the cell anode, oxides with different Ni molar fractions (0.50 or 0.85) are synthesized by the sol–gel method, followed by calcination in air at different temperatures (400 or 800 °C). To fabricate the cell cathode, the oxides are reduced in a H₂/Ar atmosphere. Electrochemical testing reveals that phase purity and average crystal size significantly influence cell performance. Highly pure and finely grained electrocatalysts yield higher current densities at lower overpotentials. The best performing membrane electrode assembly exhibits a current density of 1 A cm⁻² at 2.15 V during a steady-state 150 h long stability test with 1 M KOH recirculating through the cell, the lowest series resistance at any cell potential (1.8 or 2.0 V), and the highest current density at the cut-off voltage (2.2 V) both at the beginning (1 A cm⁻²) and end of tests (1.78 A cm⁻²). The presented results pave the way to obtain, via simple and scalable techniques, cost-effective catalysts for the production of green hydrogen aimed at a wider market penetration by AEMWE. Full article

(This article belongs to the Special Issue Advances in Nanostructured Electrode Materials: Design and Applications)

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15 pages, 1555 KiB

Open AccessArticle

Synthesis and Characterization of Temperature- and pH-Responsive PIA-b-PNIPAM@Fe₃O₄ Nanocomposites

by Swati Kumari, Cayla Cook, Fatema Tarannum, Erick S. Vasquez-Guardado, Olufemi Ogunjimi and Keisha B. Walters

Nanomaterials 2025, 15(13), 1041; https://doi.org/10.3390/nano15131041 - 4 Jul 2025

Abstract

Stimuli-responsive polymers (SRPs) have garnered significant attention in recent decades due to their immense potential in biomedical and environmental applications. When these SRPs are grafted onto magnetic nanoparticles, they form multifunctional nanocomposites capable of various complex applications, such as targeted drug delivery, advanced [...] Read more.

Stimuli-responsive polymers (SRPs) have garnered significant attention in recent decades due to their immense potential in biomedical and environmental applications. When these SRPs are grafted onto magnetic nanoparticles, they form multifunctional nanocomposites capable of various complex applications, such as targeted drug delivery, advanced separations, and magnetic resonance imaging. In this study, we employed a one-step hydrothermal method using 3-aminopropyltrimethoxysilane (APTES) to synthesize APTES-modified Fe₃O₄ nanoparticles (APTES@Fe₃O₄) featuring reactive terminal amine groups. Subsequently, via two consecutive surface-initiated atom transfer radical polymerizations (SI-ATRP), pH- and temperature-responsive polymer blocks were grown from the Fe₃O₄ surface, resulting in the formation of poly(itaconic acid)-block-poly(N-isopropyl acrylamide) (PIA-b-PNIPAM)-grafted nanomagnetic particles (PIA-b-PNIPAM@Fe₃O₄). To confirm the chemical composition and assess how the particle morphology and size distribution of these SRP-based nanocomposites change in response to ambient pH and temperature stimuli, various characterization techniques were employed, including transmission electron microscopy, differential light scattering, and Fourier transform infrared spectroscopy. The results indicated successful synthesis, with PIA-b-PNIPAM@Fe₃O₄ demonstrating sensitivity to both temperature and pH. Full article

(This article belongs to the Section Nanocomposite Materials)

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16 pages, 3506 KiB

Open AccessArticle

Biological Impact of True-to-Life PET and Titanium-Doped PET Nanoplastics on Human-Derived Monocyte (THP-1) Cells

by Aliro Villacorta, Michelle Morataya-Reyes, Lourdes Vela, Jéssica Arribas Arranz, Joan Martín-Perez, Irene Barguilla, Ricard Marcos and Alba Hernández

Nanomaterials 2025, 15(13), 1040; https://doi.org/10.3390/nano15131040 - 4 Jul 2025

Abstract

In the environment, plastic waste degrades into small particles known as microplastics and nanoplastics (MNPLs), depending on their size. Given the potential harmful effects associated with MNPL exposure, it is crucial to develop environmentally representative particles for hazard assessment. These so-called true-to-life MNPLs [...] Read more.

In the environment, plastic waste degrades into small particles known as microplastics and nanoplastics (MNPLs), depending on their size. Given the potential harmful effects associated with MNPL exposure, it is crucial to develop environmentally representative particles for hazard assessment. These so-called true-to-life MNPLs are generated through in-house degradation of real-world plastic products. In this study, we produced titanium-doped nanoplastics (NPLs) from opaque polyethylene terephthalate (PET) milk bottles, which contain titanium dioxide as a filler. The resulting PET(Ti)-NPLs were thoroughly characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), mass spectrometry (MS), dynamic light scattering (DLS), ζ-potential measurements, transmission electron microscopy (TEM), and Fourier-transform infrared (FTIR) spectroscopy. Human-derived THP-1 monocytes were employed to investigate particle uptake kinetics, dosimetry, and genotoxicity. A combination of flow cytometry and inductively coupled plasma mass spectrometry (ICP-MS) enabled the quantification of internalized particles, while the comet assay assessed DNA damage. The results revealed dose- and time-dependent effects of PET(Ti)-NPLs on THP-1 cells, particularly in terms of internalization. Titanium doping facilitated detection and influenced genotoxic outcomes. This study demonstrates the relevance of using environmentally representative nanoplastic models for evaluating human health risks and underscores the importance of further mechanistic research. Full article

(This article belongs to the Section Biology and Medicines)

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19 pages, 2086 KiB

Open AccessArticle

Strategic Doping for Precise Structural Control and Intense Photocurrents Under Visible Light in Ba₂M_0.4Bi_1.6O₆ (M = La, Ce, Pr, Pb, Y) Double Perovskites

by Tirong Guo, Wen Tian Fu and Huub J. M. de Groot

Nanomaterials 2025, 15(13), 1039; https://doi.org/10.3390/nano15131039 - 4 Jul 2025

Abstract

Developing functional perovskites is important for advancing solar energy conversion technologies. This study investigates the effects of dopants on the structural, optical, electronic, and solar conversion performances of Ba₂M_0.4Bi_1.6O₆ double perovskites. X-ray diffraction (XRD) and Rietveld [...] Read more.

Developing functional perovskites is important for advancing solar energy conversion technologies. This study investigates the effects of dopants on the structural, optical, electronic, and solar conversion performances of Ba₂M_0.4Bi_1.6O₆ double perovskites. X-ray diffraction (XRD) and Rietveld refinement confirm crystallization in the I2/m space group (M = La, Ce, Pr, Pb), and Fm

\bar{3}

m and I2/m space groups (M = Y). The B1-O-B2 structure modulates to highly ordered (M = La, Y), partially ordered (M = Pr), or disordered (M = Ce, Pb). UV-vis spectra show strong light absorption, with Tauc plots estimating ~1.57 eV (M = La) and ~1.73 eV (M = Pr) optical band gaps. Under AM 1.5G illumination, the M = La photoelectrode generates photocurrents of 1 mA cm⁻² at 0.3 V_RHE, surpassing M = Ce and Pb (1 μm, 4-times spin-coating). Increasing its thickness to 7.7 μm (4-times dip-coating) further enhances the photocurrents to 2.3 mA cm⁻² at 0.2 V_RHE, outperforming all counterparts due to improved stability. Fine-tuning crystal and electronic structures via strategic B-site doping provides a new route for engineering Ba₂Bi₂O₆-based double perovskites for broad solar energy conversion applications. Full article

(This article belongs to the Special Issue Organic/Perovskite Solar Cell)

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20 pages, 4646 KiB

Open AccessReview

Vanadium-Based MXenes: Types, Synthesis, and Recent Advances in Supercapacitor Applications

by Zhiwei Gao, Donghu Shi, Jiawei Xu, Te Hai, Yao Zhao, Meng Qin and Jian Li

Nanomaterials 2025, 15(13), 1038; https://doi.org/10.3390/nano15131038 - 4 Jul 2025

Abstract

Since the discovery of two-dimensional transition metal carbides and nitrides (MXenes), MXenes have attracted widespread research in the academic community due to their advantages, such as adjustable interlayer spacing, excellent hydrophilicity, conductivity, compositional diversity, and rich surface chemical composition. More than 100 different [...] Read more.

Since the discovery of two-dimensional transition metal carbides and nitrides (MXenes), MXenes have attracted widespread research in the academic community due to their advantages, such as adjustable interlayer spacing, excellent hydrophilicity, conductivity, compositional diversity, and rich surface chemical composition. More than 100 different MXene combinations can be calculated theoretically, but only more than 40 have been successfully synthesized through experiments. Among the many synthesized and reported MXene materials, vanadium-based carbide MXenes, represented by V₂CT_x and V₄C₃T_x, show excellent application prospects in energy storage and have become the focus of researchers. In this review, we mainly discuss the structure, characteristics, and preparation methods of vanadium-based MXene precursors in the MAX phase and their applications in supercapacitors. Finally, we propose the main challenges existing at the current stage of vanadium-based materials and their heterostructures and provide a perspective on future research directions. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Energetic Application: Experiment and Simulation)

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12 pages, 1250 KiB

Open AccessArticle

Probing the Structural Order of Half-Heusler Phases in Sb-Doped (Ti,Zr,Hf)NiSn Thermoelectrics

by Fani Pinakidou, Andreas Delimitis and Maria Katsikini

Nanomaterials 2025, 15(13), 1037; https://doi.org/10.3390/nano15131037 - 3 Jul 2025

Abstract

The nanostructural features of a mechanically alloyed Sb-doped (Ti_0.4Zr_0.6)_0.7Hf_0.3NiSn thermoelectric (TE) Half-Heusler (HH) compound were addressed using Transmission Electron Microscopy (TEM) coupled with Energy Dispersive Spectroscopy measurements and Extended X-Ray Absorption Fine Structure (EXAFS) spectroscopy. [...] Read more.

The nanostructural features of a mechanically alloyed Sb-doped (Ti_0.4Zr_0.6)_0.7Hf_0.3NiSn thermoelectric (TE) Half-Heusler (HH) compound were addressed using Transmission Electron Microscopy (TEM) coupled with Energy Dispersive Spectroscopy measurements and Extended X-Ray Absorption Fine Structure (EXAFS) spectroscopy. The EXAFS measurements at the Ni-K, Sn-K, Zr-K, and Hf-L₃-edge were implemented in an effort to reveal the influence of Hf and Zr incorporation into the crystal with respect to their previously measured TE properties. The substitution of Ti by Hf and Zr is expected to yield local lattice distortions due to the different atomic sizes of the dopants or/and electronic charge redistribution amongst the cations. However, the material is characterised by a high degree of crystallinity in both the short and long-range order, on average, and the nominal stoichiometry is identified as (Zr_0.42Hf_0.30Ti_0.28)NiSn_0.98Sb_0.02. The synergistic effect of minimization of extended structural defects or lattice distortions and considerable alloying-induced point defect population contributes to the improved TE properties and leads to the previously reported enhancement of the figure of merit of the mixed HHs. Full article

(This article belongs to the Special Issue Nanoscale Thermoelectric Materials: Advanced Synthesis and Characterisation Approaches)

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20 pages, 6691 KiB

Open AccessArticle

An Easy and Single-Step Biosynthesis of WO₃ with High Photocatalytic Degradation Activity for Dye Degradation

by Azza A. Al-Ghamdi, Reema H. Aldahiri, Elham A. Alzahrani, Naha Meslet Alsebaii, Sumbul Hafeez, Shafiul Haque, Poonam Dwivedi and Seungdae Oh

Nanomaterials 2025, 15(13), 1036; https://doi.org/10.3390/nano15131036 - 3 Jul 2025

Abstract

In the present study, a photodegradation technique was employed for the removal of methylene blue dye from aqueous solution using a tungsten oxide-based photocatalyst. The photocatalyst was synthesized via a green synthesis route utilizing a plant extract (PE) under acidic conditions. The synthesized [...] Read more.

In the present study, a photodegradation technique was employed for the removal of methylene blue dye from aqueous solution using a tungsten oxide-based photocatalyst. The photocatalyst was synthesized via a green synthesis route utilizing a plant extract (PE) under acidic conditions. The synthesized photocatalyst was characterized by various spectroscopic and microscopic techniques that confirmed the presence of various functional groups on the catalyst surface and revealed a narrow bandgap of ~3.0 eV. The synthesized particles exhibited a nanoscale dimension ranging from 10 to 15 nm. The photocatalytic activity of the material was evaluated under ultraviolet light, visible light, and sunlight irradiation, demonstrating the efficient degradation of methylene blue under all light sources. Furthermore, catalysis reusability studies indicated excellent stability, with consistent photocatalytic performance observed after five successive cycles. Full article

(This article belongs to the Special Issue Application of Nanotechnology in Detection and Removal of Pollutants in Water System)

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13 pages, 10650 KiB

Open AccessArticle

Barrier-Free Carrier Injection in 2D WSe₂-MoSe₂ Heterostructures via Fermi-Level Depinning

by Tian-Jun Dai, Xiang Xiao, Zhong-Yuan Fan, Zi-Yan Zhang, Yi Zhou, Yong-Chi Xu, Jian Sun and Xue-Fei Liu

Nanomaterials 2025, 15(13), 1035; https://doi.org/10.3390/nano15131035 - 3 Jul 2025

Abstract

Fermi-level pinning (FLP) at metal–semiconductor interfaces remains a key obstacle to achieving low-resistance contacts in two-dimensional (2D) transition metal dichalcogenide (TMDC)-based heterostructures. Here, we present a first-principles study of Schottky barrier formation in WSe₂-MoSe₂ van der Waals heterostructures interfaced with [...] Read more.

Fermi-level pinning (FLP) at metal–semiconductor interfaces remains a key obstacle to achieving low-resistance contacts in two-dimensional (2D) transition metal dichalcogenide (TMDC)-based heterostructures. Here, we present a first-principles study of Schottky barrier formation in WSe₂-MoSe₂ van der Waals heterostructures interfaced with four representative metals (Ag, Al, Au, and Pt). It was found that all metal–WSe₂/MoSe₂ direct contacts induce pronounced metal-induced gap states (MIGSs), leading to significant FLP inside the WSe₂/MoSe₂ band gaps and elevated Schottky barrier heights (SBHs) greater than 0.31 eV. By introducing a 2D metal-doped metallic (mWSe/mMoSe) layer between WSe₂/MoSe₂ and the metal electrodes, the MIGSs can be effectively suppressed, resulting in nearly negligible SBHs for both electrons and holes, with even an SBH of 0 eV observed in the Ag-AgMoSe-MoSe₂ contact, thereby enabling quasi-Ohmic contact behavior. Our results offer a universal and practical strategy to mitigate FLP and achieve high-performance TMDC-based electronic devices with ultralow contact resistance. Full article

(This article belongs to the Section Nanoelectronics, Nanosensors and Devices)

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22 pages, 7596 KiB

Open AccessArticle

Optimization of Solid Lipid Nanoparticle Formulation Using Design of Experiments, PART I: Strategic Tool for the Determination of Critical Parameters Regarding Formulation and Process

by Margot Cassayre, Dany Teles de Souza, Magalie Claeys-Bruno, Alexandre Altié, Philippe Piccerelle and Christophe Sauzet

Nanomaterials 2025, 15(13), 1034; https://doi.org/10.3390/nano15131034 - 3 Jul 2025

Abstract

This study presents a methodological framework for optimizing “blank” solid lipid nanoparticles (SLNs), focusing on the use of a design of experiments (DOE) approach. Rather than emphasizing the applications of SLNs, the objective is to identify and optimize critical formulation and process parameters—specifically [...] Read more.

This study presents a methodological framework for optimizing “blank” solid lipid nanoparticles (SLNs), focusing on the use of a design of experiments (DOE) approach. Rather than emphasizing the applications of SLNs, the objective is to identify and optimize critical formulation and process parameters—specifically those influencing particle size (PS), polydispersity index (PDI), and zeta potential (ZP)—during early development stages. A non-classical mixed design was applied using AZURAD^® software (version 4.4.1), incorporating a mixture variable for lipid composition (comprising carnauba wax, glyceryl behenate, glyceryl distearate), and two quantitative factors: the percentage of polysorbate 80 (P80) in the P80/sorbitan oleate surfactant system and ultrasound (US) treatment time. The DOE analysis identified P80 concentration as a key parameter, with optimal formulations observed when P80 ranged between 35% and 45%. A fixed P80 ratio of 41% and a US time of 7.5 min enabled precise adjustment of lipid composition. Following a desirability function analysis, an optimized formulation was obtained with a PS of 176.3 ± 2.78 nm, a PDI of 0.268 ± 0.022, and a ZP of −35.5 ± 0.36 mV. These findings validate the relevance of our DOE-based strategy, offering a scalable, cost-effective platform that reduces material use, time, and analytical effort in SLN development. Full article

(This article belongs to the Special Issue Modeling, Simulation and Optimization of Nanomaterials)

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16 pages, 2468 KiB

Open AccessArticle

Multi-Bit Resistive Random-Access Memory Based on Two-Dimensional MoO₃ Layers

by Kai Liu, Wengui Jiang, Liang Zhou, Yinkang Zhou, Minghui Hu, Yuchen Geng, Yiyuan Zhang, Yi Qiao, Rongming Wang and Yinghui Sun

Nanomaterials 2025, 15(13), 1033; https://doi.org/10.3390/nano15131033 - 3 Jul 2025

Abstract

Two-dimensional (2D) material-based resistive random-access memory (RRAM) has emerged as a promising solution for neuromorphic computing and computing-in-memory architectures. Compared to conventional metal-oxide-based RRAM, the novel 2D material-based RRAM devices demonstrate lower power consumption, higher integration density, and reduced performance variability, benefiting from [...] Read more.

Two-dimensional (2D) material-based resistive random-access memory (RRAM) has emerged as a promising solution for neuromorphic computing and computing-in-memory architectures. Compared to conventional metal-oxide-based RRAM, the novel 2D material-based RRAM devices demonstrate lower power consumption, higher integration density, and reduced performance variability, benefiting from their atomic-scale thickness and ultra-flat surfaces. Remarkably, 2D layered metal oxides retain these advantages while preserving the merits of traditional metal oxides, including their low cost and high environmental stability. Through a multi-step dry transfer process, we fabricated a Pd-MoO₃-Ag RRAM device featuring 2D α-MoO₃ as the resistive switching layer, with Pd and Ag serving as inert and active electrodes, respectively. Resistive switching tests revealed an excellent operational stability, low write voltage (~0.5 V), high switching ratio (>10⁶), and multi-bit storage capability (≥3 bits). Nevertheless, the device exhibited a limited retention time (~2000 s). To overcome this limitation, we developed a Gr-MoO₃-Ag heterostructure by substituting the Pd electrode with graphene (Gr). This modification achieved a fivefold improvement in the retention time (>10⁴ s). These findings demonstrate that by controlling the type and thickness of 2D materials and resistive switching layers, RRAM devices with both high On/Off ratios and long-term data retention may be developed. Full article

(This article belongs to the Special Issue The 15th Anniversary of Nanomaterials—2D Materials and Heterostructures: Synthesis, Processing, and Device Applications)

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30 pages, 1472 KiB

Open AccessReview

Evaluating Biocompatibility: From Classical Techniques to State-of-the-Art Functional Proteomics

by Ana Nuño-Soriano, Carlota Arias-Hidalgo, Enrique Montalvillo, Rafael Góngora, Ángela-Patricia Hernández, Pablo Juanes-Velasco and Manuel Fuentes

Nanomaterials 2025, 15(13), 1032; https://doi.org/10.3390/nano15131032 - 3 Jul 2025

Abstract

Biocompatibility remains a central issue for introducing biomaterials and nanomedicines into the clinic, requiring safety, functionality, toxicity prevention, and the control of foreign body reactions. Therefore, it is necessary to evaluate multiple biomaterial parameters and molecular interactions affecting cell functions, like apoptosis, adhesion, [...] Read more.

Biocompatibility remains a central issue for introducing biomaterials and nanomedicines into the clinic, requiring safety, functionality, toxicity prevention, and the control of foreign body reactions. Therefore, it is necessary to evaluate multiple biomaterial parameters and molecular interactions affecting cell functions, like apoptosis, adhesion, proliferation, or spreading, as well as intracellular signals and cellular microenvironment status. Although conventional well-established in vitro techniques are helpful at the first stages of bio and nanomaterials development, high-throughput techniques expand the screening and designing possibilities. This review presents high-throughput functional proteomics approaches, focused on protein microarrays and mass spectrometry techniques, for the evaluation of biocompatibility in the new era of biomedicine. Full article

(This article belongs to the Section Biology and Medicines)

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14 pages, 8408 KiB

Open AccessArticle

MRE Encapsulating MRG: Synergistic Improvement in Modulus Tunability and Energy Dissipation

by Mi Zhu, Wang Li, Qi Hou and Yanmei Li

Nanomaterials 2025, 15(13), 1031; https://doi.org/10.3390/nano15131031 - 3 Jul 2025

Abstract

Traditional magnetorheological elastomers (MREs) often suffer from limited modulus tunability and insufficient energy dissipation, which restrict their applications. This study prepared a novel composite material by an MR gel (MRG) embedded within the MRE, called the MRE encapsulating MRG, to synergistically enhance these [...] Read more.

Traditional magnetorheological elastomers (MREs) often suffer from limited modulus tunability and insufficient energy dissipation, which restrict their applications. This study prepared a novel composite material by an MR gel (MRG) embedded within the MRE, called the MRE encapsulating MRG, to synergistically enhance these properties. Annular and radial MRE encapsulating MRG configurations were fabricated using 3D-printed molds, and their dynamic mechanical performance was characterized under varying magnetic fields (0–1 T) via a rheometer. The results revealed that the composite materials demonstrated significantly improved magnetic-induced modulus and magnetorheological (MR) effects compared to conventional MREs. Specifically, the annular MRE encapsulating MRG exhibited a 238.47% increase in the MR effect and a 51.35% enhancement in the magnetic-induced modulus compared to traditional MREs. Correspondingly, the radial configuration showed respective improvements of 168.19% and 27.03%. Furthermore, both the annular and radial composites displayed superior energy dissipation capabilities, with loss factors 2.68 and 2.03 times greater than those of pure MREs, respectively. Dynamic response tests indicated that composite materials, particularly the annular MRE encapsulating MRG, achieve faster response times. These advancements highlight the composite’s potential for high-precision damping systems, vibration isolation, and adaptive control applications. Full article

(This article belongs to the Section Nanocomposite Materials)

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24 pages, 1605 KiB

Open AccessReview

Zinc Oxide Nanoparticles as Next-Generation Feed Additives: Bridging Antimicrobial Efficacy, Growth Promotion, and Sustainable Strategies in Animal Nutrition

by Jiayi Yang, Dongwei Xiong and Miao Long

Nanomaterials 2025, 15(13), 1030; https://doi.org/10.3390/nano15131030 - 2 Jul 2025

Abstract

Zinc oxide nanoparticles (ZnO NPs) have attracted significant attention due to their wide-ranging applications in animal production, largely because of their notable biocompatibility, low toxicity, and strong antimicrobial activity. These properties make ZnO NPs a promising substitute for traditional antibiotics. Their application could [...] Read more.

Zinc oxide nanoparticles (ZnO NPs) have attracted significant attention due to their wide-ranging applications in animal production, largely because of their notable biocompatibility, low toxicity, and strong antimicrobial activity. These properties make ZnO NPs a promising substitute for traditional antibiotics. Their application could address the growing concern of antibiotic resistance in livestock industries. This review examines the unique physicochemical characteristics of ZnO NPs, including their nanoscale size and high surface area, which contribute to their biological functionality. Emphasis is placed on green synthesis methods that minimize environmental impact while producing high-quality ZnO NPs. In animal farming, ZnO NPs play a crucial role not only in promoting growth and improving immune responses, but also in enhancing meat and egg quality. Additionally, this review discusses the environmental and safety implications of ZnO NPs, considering their sustainable application potential in future animal production practices, aimed at fostering a more eco-friendly and efficient livestock sector. Full article

(This article belongs to the Section Environmental Nanoscience and Nanotechnology)

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33 pages, 2373 KiB

Open AccessArticle

Effect of Ga₂O₃ Content on the Activity of Al₂O₃-Supported Catalysts for the CO₂-Assisted Oxidative Dehydrogenation of Propane

by Alexandra Florou, Georgios Bampos, Panagiota D. Natsi, Aliki Kokka and Paraskevi Panagiotopoulou

Nanomaterials 2025, 15(13), 1029; https://doi.org/10.3390/nano15131029 - 2 Jul 2025

Abstract

Propylene production through the CO₂-assisted oxidative dehydrogenation of propane (CO₂-ODP) is an effective route able to address the ever-increasing demand for propylene and simultaneously utilize CO₂. In this study, a series of alumina-supported gallium oxide catalysts of [...] Read more.

Propylene production through the CO₂-assisted oxidative dehydrogenation of propane (CO₂-ODP) is an effective route able to address the ever-increasing demand for propylene and simultaneously utilize CO₂. In this study, a series of alumina-supported gallium oxide catalysts of variable Ga₂O₃ loading was synthesized, characterized, and evaluated with respect to their activity for the CO₂-ODP reaction. It was found that both the catalysts’ physicochemical characteristics and performance were strongly affected by the amount of Ga₂O₃ dispersed on Al₂O₃. Surface basicity was maximized for the sample containing 20 wt.% Ga₂O₃, whereas surface acidity was monotonically increased with increasing Ga₂O₃ loading. A volcano-type correlation was found between catalytic performance and acid/base properties, according to which propane conversion and propylene yield exhibited optimum values for intermediate surface basicity and acidity, which both correspond to the sample containing 30 wt.% Ga₂O₃. The dispersion of a suitable amount of Ga₂O₃ on the Al₂O₃ surface not only enhances the conversion of propane to propylene but also suppresses the formation of side products (C₂H₄, CH₄, and C₂H₆) at temperatures of practical interest. The 30%Ga₂O₃-Al₂O₃ catalyst exhibited very good stability at 550 °C, where byproduct formation and carbon deposition were limited. Mechanistic studies indicated that the reaction proceeds through a two-step oxidative route with the participation of CO₂ in the abstraction of H₂, originating from propane dehydrogenation, through the reverse water–gas reaction (RWGS) reaction, shifting the thermodynamic equilibrium towards propylene generation. Full article

(This article belongs to the Special Issue Nanoscale Material Catalysis for Environmental Protection)

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19 pages, 7364 KiB

Open AccessArticle

Sustainable Sugarcane Bagasse-Derived Activated Carbon for High-Performance Symmetric Supercapacitor Devices Applications

by Perumal Rajivgandhi, Vediyappan Thirumal, Alagan Sekar and Jinho Kim

Nanomaterials 2025, 15(13), 1028; https://doi.org/10.3390/nano15131028 - 2 Jul 2025

Abstract

In this study, sugarcane bagasse (SCB), an abundant agricultural byproduct, was transformed into activated carbon via a controlled thermochemical pyrolysis route for high-performance energy storage applications. Herein, we utilized the activated carbon derived from pure sugarcane bagasse (SCB-AC) and further activated using KOH [...] Read more.

In this study, sugarcane bagasse (SCB), an abundant agricultural byproduct, was transformed into activated carbon via a controlled thermochemical pyrolysis route for high-performance energy storage applications. Herein, we utilized the activated carbon derived from pure sugarcane bagasse (SCB-AC) and further activated using KOH (SCB-KOH-AC) as an electrode material in aqueous symmetric supercapacitor configurations. The synthesized activated carbon was subjected to analysis using a range of characteristics including FT-Raman spectroscopy, which was employed to confirm the functional groups present in the carbon materials. The XPS analysis provided insights into the elemental composition and ionic states. The SEM analysis revealed that both activated carbon and KOH/activated carbon materials exhibited a layered or stacked, albeit slightly random, orientation. Electrochemical studies demonstrated that the synthesized carbon electrodes exhibited impressive specific capacitance values of (SCB) activated carbon (132.20 F/g) and KOH-activated, pure SCB AC (SCB-A) 253.41 F/g at 0.5 A/g. Furthermore, the SCB KOH-activated carbon (AC) electrode revealed a higher specific capacitance value and A//SCB-A symmetric devices delivered energy density reaching 17.91 Wh/kg and power density up to 2990 W/kg. The KOH-activated carbon electrode demonstrated remarkable cycling stability retaining 93.89%, even after 10,000 cycles. These results suggest that the sugarcane bagasse-derived activated carbon is a sustainable and low-cost candidate for next-generation supercapacitor electrodes. The results demonstrate enhanced capacitance, stability, and pore structure tailored for energy storage applications. The KOH-activated carbon SCB carbon symmetric device with symmetric electrodes exhibited a suitable bio-mass carbon for future energy storage applications. Full article

(This article belongs to the Section Energy and Catalysis)

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15 pages, 2628 KiB

Open AccessArticle

High Anti-Swelling Zwitterion-Based Hydrogel with Merit Stretchability and Conductivity for Motion Detection and Information Transmission

by Qingyun Zheng, Jingyuan Liu, Rongrong Chen, Qi Liu, Jing Yu, Jiahui Zhu and Peili Liu

Nanomaterials 2025, 15(13), 1027; https://doi.org/10.3390/nano15131027 - 2 Jul 2025

Abstract

Hydrogel sensors show unique advantages in underwater detection, ocean monitoring, and human–computer interaction because of their excellent flexibility, biocompatibility, high sensitivity, and environmental adaptability. However, due to the water environment, hydrogels will dissolve to a certain extent, resulting in insufficient mechanical strength, poor [...] Read more.

Hydrogel sensors show unique advantages in underwater detection, ocean monitoring, and human–computer interaction because of their excellent flexibility, biocompatibility, high sensitivity, and environmental adaptability. However, due to the water environment, hydrogels will dissolve to a certain extent, resulting in insufficient mechanical strength, poor long-term stability, and signal interference. In this paper, a double-network structure was constructed by polyvinyl alcohol (PVA) and poly([2-(methacryloyloxy) ethyl]7 dimethyl-(3-sulfopropyl) ammonium hydroxide) (PSBMA). The resultant PVA/PSBMA-PA hydrogel demonstrated notable swelling resistance, a property attributable to the incorporation of non-covalent interactions (electrostatic interactions and hydrogen bonding) through the addition of phytic acid (PA). The hydrogel exhibited high stretchability (maximum tensile strength up to 304 kPa), high conductivity (5.8 mS/cm), and anti-swelling (only 1.8% swelling occurred after 14 days of immersion in artificial seawater). Assembled as a sensor, it exhibited high strain sensitivity (0.77), a low detection limit (1%), and stable electrical properties after multiple tensile cycles. The utilization of PVA/PSBMA-PA hydrogel as a wearable sensor shows promise for detecting human joint movements, including those of the fingers, wrists, elbows, and knees. Due to the excellent resistance to swelling, the PVA/PSBMA-PA-based sensors are also suitable for underwater applications, enabling the detection of underwater mannequin motion. This study proposes an uncomplicated and pragmatic methodology for producing hydrogel sensors suitable for use within subaquatic environments, thereby concomitantly broadening the scope of applications for wearable electronic devices. Full article

(This article belongs to the Special Issue Nanomaterials in Flexible Sensing and Devices)

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20 pages, 4689 KiB

Open AccessArticle

Novel Core–Shell Metal Oxide Nanofibers with Advanced Optical and Magnetic Properties Deposited by Co-Axial Electrospinning

by Roman Viter, Viktor Zabolotnii, Martin Sahul, Mária Čaplovičová, Iryna Tepliakova, Viesturs Sints and Ambra Fioravanti

Nanomaterials 2025, 15(13), 1026; https://doi.org/10.3390/nano15131026 - 2 Jul 2025

Abstract

Co-axial electrospinning is one of the facile methods for the fabrication of core–shell metal oxides for environmental applications. Indeed, core–shell architectures featuring a magnetic core and a photocatalytic shell represent a novel approach to catalytic nanostructures in applications such as water treatment and [...] Read more.

Co-axial electrospinning is one of the facile methods for the fabrication of core–shell metal oxides for environmental applications. Indeed, core–shell architectures featuring a magnetic core and a photocatalytic shell represent a novel approach to catalytic nanostructures in applications such as water treatment and pollutant removal via magnetic separation. This study focuses on the fabrication of novel Fe₃O₄-Fe₂NiO₄/NiO core–shell nanofibers with enhanced optical and magnetic properties using co-axial electrospinning. The aim is to optimize the fabrication parameters, particularly the amount of metal precursor in the starting solutions, to achieve well-defined core and shell structures (rather than single-phase spinels), and to investigate phase transitions, structural characteristics, as well as the optical and magnetic properties of the resulting nanofibers. Raman, XRD, and XPS results show several phases and high defect concentration in the NiO shell. The Fe₃O₄-Fe₂NiO₄/NiO core–shell nanofibers exhibit strong visible-light absorption and significant magnetization. These advanced properties highlight their potential in photocatalytic applications. Full article

(This article belongs to the Special Issue Nanomaterials for Advanced Fibers and Textiles)

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Graphical abstract

21 pages, 2913 KiB

Open AccessArticle

Analysis of Transition from Compact to Mossy Structures During Galvanostatic Zinc Electrodeposition and Its Implications for CO₂ Electroreduction

by Pietro Altimari, Silvia Iacobelli, Pier Giorgio Schiavi, Gianluca Zanellato, Francesco Amato, Andrea Giacomo Marrani, Olga Russina, Alessia Sanna and Francesca Pagnanelli

Nanomaterials 2025, 15(13), 1025; https://doi.org/10.3390/nano15131025 - 2 Jul 2025

Abstract

The galvanostatic electrodeposition of zinc on carbon paper from mildly acidic solutions (ZnCl₂: 0.05–0.1 M; H₃BO₃: 0.05 M) was investigated. The deposits’ growth mechanisms were analyzed through the study of the electrodeposition potential transients and the physical [...] Read more.

The galvanostatic electrodeposition of zinc on carbon paper from mildly acidic solutions (ZnCl₂: 0.05–0.1 M; H₃BO₃: 0.05 M) was investigated. The deposits’ growth mechanisms were analyzed through the study of the electrodeposition potential transients and the physical characterization of the electrodes synthesized by varying the current density, transferred charge, and zinc precursor concentration. The analysis reveals that the transition from crystalline to amorphous mossy deposits takes place via the electrodeposition of metallic zinc followed by the formation of oxidized zinc structures. The time required for this transition can be controlled by varying the zinc precursor concentration and electrodeposition current density, allowing for the synthesis of composite zinc/oxidized zinc electrodes with varying ratios of the oxidized to underlying metallic phases. The impact of this ratio on the electrode activity for CO₂ electroreduction is analyzed, highlighting that composite zinc/oxidized zinc electrodes can achieve a faradaic efficiency to CO equal to 82% at −1.8 V vs. Ag/AgCl. The mechanisms behind the variations in the catalytic activity with varying morphologies and structures are discussed, providing guidelines for the synthesis of composite zinc/oxidized zinc electrodes for CO₂ electroreduction. Full article

(This article belongs to the Special Issue Advances in Nanostructured Catalysts for Energy and Environmental Applications)

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20 pages, 11822 KiB

Open AccessArticle

Inverse Design of Ultrathin Metamaterial Absorber

by Eunbi Jang, Junghee Cho, Chanik Kang and Haejun Chung

Nanomaterials 2025, 15(13), 1024; https://doi.org/10.3390/nano15131024 - 1 Jul 2025

Abstract

Electromagnetic absorbers combining ultrathin profiles with robust absorptivity across wide incidence angles are essential for applications such as stealth applications, wireless communications, and quantum computing. Traditional designs, including Salisbury screens, typically require thicknesses of at least a quarter-wavelength (

λ / 4

), [...] Read more.

Electromagnetic absorbers combining ultrathin profiles with robust absorptivity across wide incidence angles are essential for applications such as stealth applications, wireless communications, and quantum computing. Traditional designs, including Salisbury screens, typically require thicknesses of at least a quarter-wavelength (

λ / 4

), restricting their use in compact systems. While metamaterial absorbers (MMAs) offer reduced thicknesses, their absorptivity generally decreases under oblique incidence conditions. Here, we introduce an adjoint optimization-based inverse design method that merges the ultrathin advantage of MMAs with the angle-insensitive characteristics of Salisbury screens. By leveraging the computational efficiency of the adjoint method, we systematically optimize absorber structures as thin as

λ / 20

. The optimized structures achieve absorption exceeding 90% at the target frequency (7.5 GHz) and demonstrate robust performance under oblique incidence, maintaining over 90% absorption up to 50°, approximately 80% at 60°, and around 70% at 70°. Comparative analysis against particle swarm optimization further highlights the superior efficiency of the adjoint method, reducing the computational effort by approximately 98%. This inverse design framework thus provides substantial improvements in both the performance and computational cost, offering a promising solution for advanced electromagnetic absorber design. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Electromagnetic Shielding and Absorption Applications)

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