Nanomaterials

11 pages, 5349 KiB

Open AccessArticle

Low-Temperature Hydrotreatment of C4/C5 Fractions Using a Dual-Metal-Loaded Composite Oxide Catalyst

by Zhou Du, Renyi Li, Zhenghui Shen, Xiao Hai and Ruqiang Zou

Nanomaterials 2024, 14(23), 1934; https://doi.org/10.3390/nano14231934 (registering DOI) - 30 Nov 2024

C4 and C5 fractions are significant by-products in the ethylene industry, with considerable research and economic potential when processed through hydrogenation technology to enhance their value. This study explored the development of hydrotreating catalysts using composite oxides as carriers, specifically enhancing low-temperature performance [...] Read more.

C4 and C5 fractions are significant by-products in the ethylene industry, with considerable research and economic potential when processed through hydrogenation technology to enhance their value. This study explored the development of hydrotreating catalysts using composite oxides as carriers, specifically enhancing low-temperature performance by incorporating electronic promoters and employing specialized surface modification techniques. This approach enabled the synthesis of non-noble metal hydrogenation catalysts supported on Al₂O₃–TiO₂ composite oxides. The catalysts were characterized using various techniques, including X-ray diffraction, N₂ adsorption-desorption, scanning electron microscopy, X-ray photoelectron spectroscopy, ammonia temperature-programmed desorption, infrared spectroscopy, and transmission electron microscopy. Mo–Ni/Al₂O₃–TiO₂ catalysts were optimized for low-temperature hydrotreating of C4 and C5 fractions, demonstrating stable performance at inlet temperatures far below those typically required. This finding enables a shift from traditional gas-phase to gas–liquid two-phase reactions, eliminating the need for high-pressure steam in industrial settings. As a result, energy consumption is reduced, and operational stability is significantly improved. Full article

(This article belongs to the Section Energy and Catalysis)

31 pages, 3649 KiB

Open AccessReview

Application of Biochar-Based Materials for Effective Pollutant Removal in Wastewater Treatment

by Meiyao Han, Ziyang Liu, Shiyue Huang, Huanxing Zhang, Huilin Yang, Yuan Liu, Ke Zhang and Yusheng Zeng

Nanomaterials 2024, 14(23), 1933; https://doi.org/10.3390/nano14231933 (registering DOI) - 30 Nov 2024

Abstract

With the growth of the global population and the acceleration of industrialization, the problem of water pollution has become increasingly serious, posing a major threat to the ecosystem and human health. Traditional water treatment technologies make it difficult to cope with complex pollution, [...] Read more.

With the growth of the global population and the acceleration of industrialization, the problem of water pollution has become increasingly serious, posing a major threat to the ecosystem and human health. Traditional water treatment technologies make it difficult to cope with complex pollution, so the scientific community is actively exploring new and efficient treatment methods. Biochar (BC), as a low-cost, green carbon-based material, exhibits good adsorption and catalytic properties in water treatment due to its porous structure and abundant active functional groups. However, BC’s pure adsorption or catalytic capacity is limited, and researchers have dramatically enhanced its performance through modification means, such as loading metals or heteroatoms. In this paper, we systematically review the recent applications of BC and its modified materials for water treatment in adsorption, Fenton-like, electrocatalytic, photocatalytic, and sonocatalytic systems, and discuss their adsorption/catalytic mechanisms. However, most of the research in this field is at the laboratory simulation stage and still needs much improvement before it can be applied in large-scale wastewater treatment. This review improves the understanding of the pollutant adsorption/catalytic properties and mechanisms of BC-based materials, analyzes the limitations of the current studies, and investigates future directions. Full article

(This article belongs to the Special Issue Application of Nanomaterials in Catalysis for Pollution Control)

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10 pages, 2457 KiB

Open AccessArticle

Angle-Controlled Nanospectrum Switching from Lorentzian to Fano Lineshapes

by Fu Tang, Qinyang Zhong, Xiaoqiuyan Zhang, Yuxuan Zhuang, Tianyu Zhang, Xingxing Xu and Min Hu

Nanomaterials 2024, 14(23), 1932; https://doi.org/10.3390/nano14231932 (registering DOI) - 30 Nov 2024

Abstract

The tunability of spectral lineshapes, ranging from Lorentzian to Fano profiles, is essential for advancing nanoscale photonic technologies. Conventional far-field techniques are insufficient for studying nanoscale phenomena, particularly within the terahertz (THz) range. In this work, we use a U-shaped resonant ring on [...] Read more.

The tunability of spectral lineshapes, ranging from Lorentzian to Fano profiles, is essential for advancing nanoscale photonic technologies. Conventional far-field techniques are insufficient for studying nanoscale phenomena, particularly within the terahertz (THz) range. In this work, we use a U-shaped resonant ring on a waveguide substrate to achieve precise modulation of Lorentzian, Fano, and antiresonance profiles. THz scattering scanning near-field optical microscopy (s-SNOM) reveals the underlying physical mechanism of these transitions, driven by time-domain phase shifts between the background excitation from the waveguide and the resonance of the U-shaped ring. Our approach reveals a pronounced asymmetry in the near-field response, which remains undetectable in far-field systems. The ability to control spectral lineshapes at the nanoscale presents promising applications in characterizing composite nanoresonators and developing nanoscale phase sensors. Full article

(This article belongs to the Special Issue Light−Matter Interactions Enabled by THz Low-Dimensional Nanophotonic Structures)

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4 pages, 161 KiB

Open AccessEditorial

Functional Nanocomposites: From Strategic Design to Applications

by Li Cao and Mohammed J. Meziani

Nanomaterials 2024, 14(23), 1931; https://doi.org/10.3390/nano14231931 (registering DOI) - 30 Nov 2024

Abstract

Nanomaterials with one-, two-, or three-dimensional structures have exhibited superior optical, electronic, magnetic, thermal, and mechanical properties compared to their bulk material counterparts [...] Full article

(This article belongs to the Special Issue Functional Nanocomposites: From Strategic Design to Applications)

14 pages, 3150 KiB

Open AccessArticle

Influence of Copper Valence in CuO_x/TiO₂ Catalysts on the Selectivity of Carbon Dioxide Photocatalytic Reduction Products

by Sha Ni, Wenjing Wu, Zichao Yang, Min Zhang and Jianjun Yang

Nanomaterials 2024, 14(23), 1930; https://doi.org/10.3390/nano14231930 (registering DOI) - 29 Nov 2024

Abstract

The Cu cocatalyst supported on the surface of TiO₂ photocatalysts has demonstrated unique activity and selectivity in photocatalytic CO₂ reduction. The valence state of copper significantly influences the catalytic process; however, due to the inherent instability of copper’s valence states, the [...] Read more.

The Cu cocatalyst supported on the surface of TiO₂ photocatalysts has demonstrated unique activity and selectivity in photocatalytic CO₂ reduction. The valence state of copper significantly influences the catalytic process; however, due to the inherent instability of copper’s valence states, the precise role of different valence states in CO₂ reduction remains inadequately understood. In this study, CuO_x/TiO₂ catalysts were synthesized using an in situ growth reduction method, and we investigated the impact of various valence copper species on CO₂ photocatalytic reduction. Our results indicate that Cu⁺ and Cu⁰ serve as primary active sites, with the selectivity for CH₄ and CO products during CO₂ photoreduction being closely related to their respective ratios on the catalyst surface. The adsorption and activation mechanisms of CO on both Cu⁺ and Cu⁰ surfaces are identified as critical factors determining product selectivity in photocatalytic processes. Furthermore, it is confirmed that Cu⁺ primarily facilitates CH₄ production while Cu⁰ is responsible for generating CO. This study provides valuable insights into developing highly selective photocatalysts. Full article

(This article belongs to the Special Issue Nanomaterials for Photocatalytic Degradation of Pollutant and Hydrogen Evolution)

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17 pages, 1626 KiB

Open AccessArticle

Antibacterial and Photocatalytic Activities of Leonotis ocymifolia (L. ocymifolia)-Mediated ZnO Nanoparticles Annealed at Different Temperatures

by Dorcas Mutukwa, Raymond Tichaona Taziwa, Shepherd Masimba Tichapondwa and Lindiwe Khotseng

Nanomaterials 2024, 14(23), 1929; https://doi.org/10.3390/nano14231929 (registering DOI) - 29 Nov 2024

Abstract

This research achieved the successful synthesis of zinc oxide (ZnO) NPs through an eco-friendly method, utilizing the leaf extract of Leonotis ocymifolia (L.O.). This innovative approach not only highlights the potential of green synthesis but also underscores the effectiveness of natural resources in [...] Read more.

This research achieved the successful synthesis of zinc oxide (ZnO) NPs through an eco-friendly method, utilizing the leaf extract of Leonotis ocymifolia (L.O.). This innovative approach not only highlights the potential of green synthesis but also underscores the effectiveness of natural resources in nanoparticle production. The influence of annealing temperature on the properties and performance of the synthesized ZnO NPs was evaluated by varying the annealing temperatures as follows: unannealed (000), 350 °C (350), 550 °C (550), and 750 °C (750). The XRD analysis of L.O-mediated ZnO NPs confirmed the synthesis of highly crystalline wurtzite-structured ZnO NPs, with calculated average crystallite sizes that ranged between 13.8 and 20.4 nm. The UV–Vis spectra revealed a single strong absorption peak ranging from 354 to 375 nm, and the absorption peaks red-shifted with an increase in annealing temperature. The SEM micrographs showed that annealing temperature had an effect on the morphology, particle size, and distribution, with the average particle of 53.7–66.3 nm. The BET analysis revealed that the surface area of the prepared ZnO NPs was between 31.6 and 13.2 m²/g. In addition to its significant impact on the characteristics of the L.O-mediated, annealing temperature notably boosts the L.O-mediated capacity to photodegrade Methylene blue (MB) dye. Moreover, it exhibited significant antibacterial efficacy against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The photodegradation studies under UV irradiation and in 180 min revealed 750 (71.1%) had the highest degradation efficiency compared to 000, 350, and 550. The antibacterial tests showed that 000 had greater antibacterial efficacy than 350, 550, and 750. The results from this work suggest that annealing temperature had a significant effect on the structural, morphological, and optical properties and performance of L.O-mediated ZnO NPs. Full article

26 pages, 11335 KiB

Open AccessArticle

Water–Gas Shift over Pt Nanoparticles Dispersed on CeO₂ and Gadolinium-Doped Ceria (GDC) Supports with Specific Nano-Configurations

by Athanasios Androulakis, Ersi Nikolaraki, Catherine Drosou, Kalliopi Maria Papazisi, Stella Balomenou, Dimitrios Tsiplakides, Konstantinos G. Froudas, Pantelis N. Trikalitis, Dimitrios P. Gournis, Paraskevi Panagiotopoulou and Ioannis V. Yentekakis

Nanomaterials 2024, 14(23), 1928; https://doi.org/10.3390/nano14231928 (registering DOI) - 29 Nov 2024

Abstract

The water–gas shift (WGS) reaction is one of the most significant reactions in hydrogen technology since it can be used directly to produce hydrogen from the reaction of CO and water; it is also a side reaction taking place in the hydrocarbon reforming [...] Read more.

The water–gas shift (WGS) reaction is one of the most significant reactions in hydrogen technology since it can be used directly to produce hydrogen from the reaction of CO and water; it is also a side reaction taking place in the hydrocarbon reforming processes, determining their selectivity towards H₂ production. The development of highly active WGS catalysts, especially at temperatures below ~450 °C, where the reaction is thermodynamically favored but kinetically limited, remains a challenge. From a fundamental point of view, the reaction mechanism is still unclear. Since specific nanoshapes of CeO₂-based supports have recently been shown to play an important role in the performance of metal nanoparticles dispersed on their surface, in this study, a comparative study of the WGS is conducted on Pt nanoparticles dispersed (with low loading, 0.5 wt.% Pt) on CeO₂ and gadolinium-doped ceria (GDC) supports of different nano-morphologies, i.e., nanorods (NRs) and irregularly faceted particle (IRFP) CeO₂ and GDC, produced by employing hydrothermal and (co-)precipitation synthesis methods, respectively. The results showed that the support’s shape strongly affected its physicochemical properties and in turn the WGS performance of the dispersed Pt nanoparticles. Nanorod-shaped CeO_2,NRs and GDC_NRs supports presented a higher specific surface area, lower primary crystallite size and enhanced reducibility at lower temperatures compared to the corresponding irregular faceted CeO_2,IRFP and GDC_IRFP supports, leading to up to 5-fold higher WGS activity of the Pt particles supported on them. The Pt/GDC_NRs catalyst outperformed all other catalysts and exhibited excellent time-on-stream (TOS) stability. A variety of techniques, namely N₂ physical adsorption–desorption (the BET method), scanning and transmission electron microscopies (SEM and TEM), powder X-ray diffraction (PXRD) and hydrogen temperature programmed reduction (H₂-TPR), were used to identify the texture, structure, morphology and other physical properties of the materials, which together with the in situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) and detailed kinetic studies helped to decipher their catalytic behavior. The enhanced metal–support interactions of Pt nanoparticles with the nanorod-shaped CeO_2,NRs and GDC_NRs supports due to the creation of more active sites at the metal–support interface, leading to significantly improved reducibility of these catalysts, were concluded to be the critical factor for their superior WGS activity. Both the redox and associative reaction mechanisms proposed for WGS in the literature were found to contribute to the reaction pathway. Full article

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

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14 pages, 1603 KiB

Open AccessArticle

Chip-Scale Aptamer Sandwich Assay Using Optical Waveguide-Assisted Surface-Enhanced Raman Spectroscopy

by Megan Makela, Dandan Tu, Zhihai Lin, Gerard Coté and Pao Tai Lin

Nanomaterials 2024, 14(23), 1927; https://doi.org/10.3390/nano14231927 (registering DOI) - 29 Nov 2024

Abstract

Chip-scale optical waveguide-assisted surface-enhanced Raman spectroscopy (SERS) that used nanoparticles (NPs) was demonstrated. The Raman signals from Raman reporter (RR) molecules on NPs can be efficiently excited by the waveguide evanescent field when the molecules are in proximity to the waveguide surface. The [...] Read more.

Chip-scale optical waveguide-assisted surface-enhanced Raman spectroscopy (SERS) that used nanoparticles (NPs) was demonstrated. The Raman signals from Raman reporter (RR) molecules on NPs can be efficiently excited by the waveguide evanescent field when the molecules are in proximity to the waveguide surface. The Raman signal was enhanced by plasmon resonance due to the NPs close to the waveguide surface. The optical waveguide mode and the NP-induced field enhancement were calculated using a finite difference method (FDM). The sensing performance of the waveguide-assisted SERS device was experimentally characterized by measuring the Raman scattering from various RRs, including 4-mercaptobenzoic acid (4-MBA), 5,5′-dithio-bis-(2-nitrobenzoic acid) (DTNB), and malachite green isothiocyanate (MGITC). The observed Raman spectral features were identified and assigned to the complex vibrational modes associated with different reporters. A low detection limit of 1 nM was achieved. In addition, the device sensing method was applied to the detection of the biomarker cardiac troponin I (cTnI) using an aptamer sandwich assay immobilized on the device surface. Overall, the optical waveguides integrated with SERS show a miniaturized sensing platform for the detection of small molecules and large proteins, potentially enabling multiplexed detection for clinically relevant applications. Full article

(This article belongs to the Special Issue Nanoscale Photonics and Metamaterials)

12 pages, 3032 KiB

Open AccessArticle

Dynamics of Blister Actuation in Laser-Induced Forward Transfer for Contactless Microchip Transfer

by DoYoung Kim, Seong Ryu, Sukang Bae, Min Wook Lee, Tae-Wook Kim, Jong-Seong Bae, Jiwon Park and Seoung-Ki Lee

Nanomaterials 2024, 14(23), 1926; https://doi.org/10.3390/nano14231926 - 29 Nov 2024

Abstract

The rapid evolution of microelectronics and display technologies has driven the demand for advanced manufacturing techniques capable of precise, high-speed microchip transfer. As devices shrink in size and increase in complexity, scalable and contactless methods for microscale placement are essential. Laser-induced forward transfer [...] Read more.

The rapid evolution of microelectronics and display technologies has driven the demand for advanced manufacturing techniques capable of precise, high-speed microchip transfer. As devices shrink in size and increase in complexity, scalable and contactless methods for microscale placement are essential. Laser-induced forward transfer (LIFT) has emerged as a transformative solution, offering the precision and adaptability required for next-generation applications such as micro-light-emitting diodes (μ-LEDs). This study optimizes the LIFT process for the precise transfer of silicon microchips designed to mimic μ-LEDs. Critical parameters, including laser energy density, laser pulse width, and dynamic release layer (DRL) thickness are systematically adjusted to ensure controlled blister formation, a key factor for successful material transfer. The DRL, a polyimide-based photoreactive layer, undergoes photothermal decomposition under 355 nm laser irradiation, creating localized pressure that propels microchips onto the receiver substrate in a contactless manner. Using advanced techniques such as three-dimensional profilometry, X-ray photoelectron spectroscopy, and ultrafast imaging, this study evaluates the rupture dynamics of the DRL and the velocity of microchips during transfer. Optimization of the DRL thickness to 1 µm and a transfer velocity of 20 m s⁻¹ achieves a transfer yield of up to 97%, showcasing LIFT’s potential in μ-LED manufacturing and semiconductor production. Full article

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16 pages, 5468 KiB

Open AccessArticle

Enhancing Methylene Blue Adsorption Performance of Ti₃C₂T_x@Sodium Alginate Foam Through Pore Structure Regulation

by Yi Hu, Hongwei Wang, Xianliang Ren, Fang Wu, Gaobin Liu, Shufang Zhang, Haijun Luo and Liang Fang

Nanomaterials 2024, 14(23), 1925; https://doi.org/10.3390/nano14231925 (registering DOI) - 29 Nov 2024

Abstract

Pore structural regulation is expected to be a facile way to enhance the adsorption performance of MXene. In this work, spherical foam composites consisting of Ti₃C₂T_x and sodium alginate (SA) were synthesized via a vacuum freeze-drying technique. By [...] Read more.

Pore structural regulation is expected to be a facile way to enhance the adsorption performance of MXene. In this work, spherical foam composites consisting of Ti₃C₂T_x and sodium alginate (SA) were synthesized via a vacuum freeze-drying technique. By varying the solution volume of Ti₃C₂T_x, four distinct Ti₃C₂T_x@SA spherical foams with honeycomb-like and lamellar structures with a pore diameter in the range of 100–300 μm were fabricated. Their methylene blue (MB) adsorption performances were then systematically compared. The results revealed that the honeycomb-like porous-structured spherical foams have a significantly higher adsorption capacity than their lamellar counterparts. Notably, the Ti₃C₂T_x@SA honeycomb-like porous foam exhibited a remarkable maximum adsorption capacity (q_m) of 969 mg/g, positioning it at the forefront of MB adsorbent materials. Respective analysis of the adsorption kinetics, thermodynamics, and isotherm model indicated that this MB adsorption of Ti₃C₂T_x@SA honeycomb-like porous foam is characterized to be a physical, endothermic, and monolayer adsorption. The Ti₃C₂T_x@SA honeycomb-like porous foam also demonstrated excellent resistance to ion interference and good reusability, further attesting to its substantial potential for practical applications. X-ray photoelectron spectroscopy (XPS) analysis was employed to elucidate the adsorption mechanism, which was found to involve the synergistic effect of electrostatic adsorption and amidation reaction. This work not only offers new avenues for the development of high-performance adsorption materials but also provides crucial insights into the structural design and performance optimization of porous materials. Full article

(This article belongs to the Special Issue Advanced Porous Nanomaterials: Synthesis, Properties, and Application (Second Edition))

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21 pages, 6957 KiB

Open AccessArticle

Impact of Metal Source Structure on the Electrocatalytic Properties of Polyacrylonitrile-Derived Co-N-Doped Oxygen Reduction Reaction Catalysts

by Arseniy Kalnin, Ksenia Kharisova, Daniil Lukyanov, Sofia Filippova, Ruopeng Li, Peixia Yang, Oleg Levin and Elena Alekseeva

Nanomaterials 2024, 14(23), 1924; https://doi.org/10.3390/nano14231924 - 29 Nov 2024

Abstract

The oxygen reduction reaction (ORR) plays a central role in energy conversion and storage technologies. A promising alternative to precious metal catalysts are non-precious metal doped carbons. Considerable efforts have been devoted to cobalt-doped carbonized polyacrylonitrile catalysts, but the optimization of their catalytic [...] Read more.

The oxygen reduction reaction (ORR) plays a central role in energy conversion and storage technologies. A promising alternative to precious metal catalysts are non-precious metal doped carbons. Considerable efforts have been devoted to cobalt-doped carbonized polyacrylonitrile catalysts, but the optimization of their catalytic performance remains a key challenge. We have proposed a multifunctional active metal source strategy based on the cobalt complex with the ligand containing pyridine and azo-fragments. This complex simultaneously provides the nitrogenous environment for the Co atoms and acts as a blowing agent due to N₂ extrusion, thus increasing the surface area and porosity of the material. This strategy provided the catalysts with a high surface area and pore volume, combined with the greater fraction of Co-N clusters, and a lesser amount and smaller size of Co metal particles compared to conventionally prepared catalysts, resulting in improved catalytic performance. In addition to strict 4-electron ORR kinetics and 383 mV overpotential, the novel catalysts exhibit limiting current values close to the Pt/C benchmark and greatly overcome the Pt in methanol tolerance. These results demonstrate the critical role of metal source structure and carbonization parameters in tailoring the structural and electrochemical properties of the catalysts. Full article

(This article belongs to the Special Issue Advanced Understanding of Metal-Based Catalysts)

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13 pages, 4524 KiB

Open AccessArticle

Self-Powered Photodetectors with High Stability Based on Se Paper/P3HT:Graphene Heterojunction

by Xuewei Yu, Yuxin Huang, Pengfan Li, Shiliang Feng, Xi Wan, Yanfeng Jiang and Pingping Yu

Nanomaterials 2024, 14(23), 1923; https://doi.org/10.3390/nano14231923 - 29 Nov 2024

Abstract

Photodetectors based on selenium (Se) have attracted significant attention because of their outstanding optoelectronic characteristics, including their rapid reactivity and high photoconductivity. However, the poor responsivity of pure Se limits their further development. In this study, a novel Se-P/P3HT:G photodetector was designed and [...] Read more.

Photodetectors based on selenium (Se) have attracted significant attention because of their outstanding optoelectronic characteristics, including their rapid reactivity and high photoconductivity. However, the poor responsivity of pure Se limits their further development. In this study, a novel Se-P/P3HT:G photodetector was designed and fabricated by combining an organic semiconductor made of poly-3-hexylthiophene mixed with graphene (P3HT:G) with self-supporting Se paper (Se-P) via spin-coating process. The device possesses a dark current of around 4.23 × 10⁻¹² A and self-powered characteristics at 300–900 nm. At zero bias voltage and 548 nm illumination, the Se-P/P3HT:G photodetector demonstrates a maximum photocurrent of 1.35 × 10⁻⁹ A (745% higher than that of Se-P at 0.1 V), a quick response time (16.2/27.6 ms), an on/off ratio of 292, and a maximum detectivity and responsivity of 6.47 × 10¹¹ Jones and 34 mA W⁻¹, respectively. Moreover, Se-P/P3HT:G exhibits superior environmental stability. After one month, the photocurrent value of the Se-P/P3HT:G device held steady at 91.4% of its initial value, and even following pre-treatment at 140 °C, the on/off ratio still remained 17 (at a retention rate of about 5.9%). The excellent thermal stability, environmental reliability, and optoelectronic performance of this heterojunction structure offer a useful pathway for the future advancement of high-performance optoelectronic devices. Full article

(This article belongs to the Special Issue Graphene and 2D Material-Based Photodetectors)

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20 pages, 6154 KiB

Open AccessReview

Plasma-Assisted Preparation of Reduced Graphene Oxide and Its Applications in Energy Storage

by Haiying Li, Yufei Han, Pengyu Qiu and Yuzhe Qian

Nanomaterials 2024, 14(23), 1922; https://doi.org/10.3390/nano14231922 - 29 Nov 2024

Abstract

Reduced graphene oxide (rGO) exhibits mechanical, optoelectronic, and conductive properties comparable to pristine graphene, which has led to its widespread use as a method for producing graphene-like materials in bulk. This paper reviews the characteristics of graphene oxide and the evolution of traditional [...] Read more.

Reduced graphene oxide (rGO) exhibits mechanical, optoelectronic, and conductive properties comparable to pristine graphene, which has led to its widespread use as a method for producing graphene-like materials in bulk. This paper reviews the characteristics of graphene oxide and the evolution of traditional reduction methods, including chemical and thermal techniques. A comparative analysis reveals that these traditional methods encounter challenges, such as toxicity and high energy consumption, while plasma reduction offers advantages like enhanced controllability, the elimination of additional reducing agents, and reduced costs. However, plasma reduction is complex and significantly influenced by process parameters. This review highlights the latest advancements in plasma technology for reducing graphene oxide, examining its effectiveness across various gas environments. Inert gas plasmas, such as argon (Ar) and helium (He), demonstrate superior reduction efficiency, while mixed gases facilitate simultaneous impurity reduction. Additionally, carbon-based gases can aid in restoring defects in graphene oxide. This paper concludes by discussing the future prospects of plasma-reduced graphene and emphasizes the importance of understanding plasma parameters to manage energy and chemical footprints for effective reduction. Full article

(This article belongs to the Special Issue Functional Polymer and Ceramic Nanocomposites)

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14 pages, 3443 KiB

Open AccessArticle

Menthol-Induced Chirality in Semiconductor Nanostructures: Chiroptical Properties of Atomically Thin 2D CdSe Nanoplatelets Capped with Enantiomeric L-(−)/D-(+)-Menthyl Thioglycolates

by Maria Yu. Skrypnik, Daria A. Kurtina, Sofia P. Karamysheva, Evgeniia A. Stepanidenko, Irina S. Vasil’eva, Shuai Chang, Alexander I. Lebedev and Roman B. Vasiliev

Nanomaterials 2024, 14(23), 1921; https://doi.org/10.3390/nano14231921 - 28 Nov 2024

Abstract

Semiconductor colloidal nanostructures capped with chiral organic molecules are a research hotspot due to their wide range of important implications for photonic and spintronic applications. However, to date, the study of chiral ligands has been limited almost exclusively to naturally occurring chiral amino [...] Read more.

Semiconductor colloidal nanostructures capped with chiral organic molecules are a research hotspot due to their wide range of important implications for photonic and spintronic applications. However, to date, the study of chiral ligands has been limited almost exclusively to naturally occurring chiral amino and hydroxy acids, which typically contain only one stereocenter. Here, we show the pronounced induction of chirality in atomically thin CdSe nanoplatelets (NPLs) by capping them with enantiopure menthol derivatives as multi-stereocenter molecules. L-(−)/D-(+)-menthyl thioglycolate, easily synthesized from L-(−)/D-(+)-menthol, is attached to Cd-rich (001) basal planes of 2- and 3-monolayer (ML) CdSe NPLs. We show the appearance of narrow sign-alternating bands in the circular dichroism (CD) spectra of 2 ML NPLs corresponding to heavy-hole (HH) and light-hole (LH) excitons with maximal dissymmetry g-factor up to 2.5 × 10⁻⁴. The most intense CD bands correspond to the lower-energy HH exciton, and in comparison with the N-acetyl-L-Cysteine ligand, the CD bands for L-(−)-menthyl thioglycolate have the opposite sign. The CD measurements are complemented with magnetic CD measurements and first-principles modeling. The obtained results may be of interest for designing new chiral semiconductor nanostructures and improving understanding of their chiroptical properties. Full article

(This article belongs to the Special Issue Nano Surface Engineering)

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11 pages, 3997 KiB

Open AccessArticle

Single-Crystalline Nanowires of Molecular Ferroelectric Semiconductors for Optoelectronic Memory

by Xinxia Qiu, Mingsheng Xu, Chunxiao Cong, Zhi-Jun Qiu, Laigui Hu and Ran Liu

Nanomaterials 2024, 14(23), 1920; https://doi.org/10.3390/nano14231920 (registering DOI) - 28 Nov 2024

Abstract

Though much progress has been achieved in the discovery of new molecular ferroelectrics in recent years, practical applications and related physics are still rarely explored due to the difficulty in high-quality film production and patterning issues. Single-crystalline films and patterns are in high [...] Read more.

Though much progress has been achieved in the discovery of new molecular ferroelectrics in recent years, practical applications and related physics are still rarely explored due to the difficulty in high-quality film production and patterning issues. Single-crystalline films and patterns are in high demand for high device performance. Through a template-assisted space-confined strategy, herein, ordered single-crystalline nanowire patterns and optoelectronic devices of a semiconducting molecular ferroelectric (SMF), hexane-1,6-diammonium pentaiodobismuth (HDA-BiI₅), were successfully demonstrated. The coupling of semiconducting and ferroelectric polarization of the SMF devices enables a broadband self-powered photodetection from ultraviolet to visible light, as well as polarization-tunable photoresponsivity. These may open an avenue for high-performance SMF optoelectronic memory devices with low cost and flexibility. Full article

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14 pages, 4331 KiB

Open AccessArticle

Efficient and Stable Deep-Blue 0D Copper-Based Halide TEA₂Cu₂I₄ with Near-Unity Photoluminescence Quantum Yield for Light-Emitting Diodes

by Fang Yuan, Xiaoyun Liu, Songting Zhang, Peichao Zhu, Fawad Ali, Chenjing Zhao, Shuaiqi He, Qianhao Ma, Jingrui Li, Kunping Guo, Lu Li and Zhaoxin Wu

Nanomaterials 2024, 14(23), 1919; https://doi.org/10.3390/nano14231919 - 28 Nov 2024

Abstract

Achieving deep-blue light with high color saturation remains a critical challenge in the development of white light-emitting diode (LED) technology, necessitating luminescent materials that excel in efficiency, low toxicity, and stability. Here, we report the synthesis of [N(C₂H₅)₄ [...] Read more.

Achieving deep-blue light with high color saturation remains a critical challenge in the development of white light-emitting diode (LED) technology, necessitating luminescent materials that excel in efficiency, low toxicity, and stability. Here, we report the synthesis of [N(C₂H₅)₄]₂Cu₂I₄ (TEA₂Cu₂I₄) single crystals (SCs), which exhibit deep-blue photoluminescence (PL) at 450 nm. These crystals are characterized by a significant Stokes shift of 180 nm, a long lifetime of 1.7 μs, and an impressive photoluminescence quantum yield (PLQY) of 96.7% for SCs and 87.2% for polycrystalline films. The zero-dimensional structure is attributed to the proper spacing of triangular inorganic units [Cu₂I₄]²⁻ by organic cations [N(C₂H₅)₄]⁺. This structural arrangement facilitates broadband deep-blue light emission with phosphorescent characteristics, as evidenced by temperature-dependent PL and time-resolved photoluminescence (TRPL) measurements. The band gap properties of TEA₂Cu₂I₄ were further elucidated through density functional theory (DFT) computations. Notably, the material exhibited minimal PL intensity degradation after continuous UV irradiation and one month of exposure to ambient conditions. Moreover, the polycrystalline film of TEA₂Cu₂I₄ maintained substantial deep-blue emission even after one year of storage. Utilizing TEA₂Cu₂I₄ thin film, we fabricated an electroluminescent device emitting deep-blue light with high color saturation, featuring CIE coordinates (0.143, 0.076) and a brightness of 90 cd/m². The exceptional photophysical properties of TEA₂Cu₂I₄ render it a highly promising candidate for optoelectronic applications. Full article

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

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12 pages, 1804 KiB

Open AccessArticle

Vibrational Spectrum of Magnesium Monochalcogenide Nanoparticles

by Nikos Aravantinos-Zafiris, Fotios I. Michos and Michail M. Sigalas

Nanomaterials 2024, 14(23), 1918; https://doi.org/10.3390/nano14231918 - 28 Nov 2024

Abstract

In this work, the vibrational spectra of magnesium monochalcogenide nanoparticles were examined numerically. The calculations were performed with Density Functional Theory and the examined magnesium monochalcogenide nanoparticles were formed from an initial cubic-like unit with type

{M g}_{4} Y_{4}

, where [...] Read more.

In this work, the vibrational spectra of magnesium monochalcogenide nanoparticles were examined numerically. The calculations were performed with Density Functional Theory and the examined magnesium monochalcogenide nanoparticles were formed from an initial cubic-like unit with type

{M g}_{4} Y_{4}

, where

Y = S, S e, T e

, after elongating this unit along one, two, and three vertical directions. Therefore, beyond the initial building block, different groups of magnesium monochalcogenide nanoparticles were examined in the form

{M g}_{x} Y_{x}

, where

x = 8, 16, 24

. Especially for the case where the chalcogen part of the nanoparticle was sulfur, another group of nanoparticles was examined where

x = 32

. For this group of the examined nanostructures, an exotic case was also included in the calculations. Among the findings of this research was the existence of stable structures, of the examined morphologies. The calculations of this research led to the identification of both common characteristics and differences among these nanostructures. These characteristics regarding their vibrational modes could be a very useful tool, especially for experimentalists. The relevant phonon spectrum that was extracted from the calculations also provided very useful information regarding the examined nanoparticles and their potential uses in several technological applications. Full article

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13 pages, 4571 KiB

Open AccessArticle

Haptic-Based Real-Time Platform for Microswarm Steering in a Multi-Bifurcation Vascular Network

by Benjamin W. Jarvis, Kiana Abolfathi, Riccardo Poli and Ali Kafash Hoshiar

Nanomaterials 2024, 14(23), 1917; https://doi.org/10.3390/nano14231917 - 28 Nov 2024

Abstract

The use of electromagnetic fields to control a collection of magnetic nanoparticles, known as a microswarm, has many promising applications. Current research often makes use of accurate but time-consuming simulations lacking real-time human input. On the contrary, human interaction is possible with a [...] Read more.

The use of electromagnetic fields to control a collection of magnetic nanoparticles, known as a microswarm, has many promising applications. Current research often makes use of accurate but time-consuming simulations lacking real-time human input. On the contrary, human interaction is possible with a real-time simulator, allowing the collection of valuable user interaction data. This paper presents the development and validation of a real-time two-dimensional microswarm simulator to accommodate the human interaction aspect. A haptic device is used to steer the microswarm through a multi-bifurcation vascular network towards a selected outlet. The percentage of particles reaching the selected outlet is used as the success metric. The simulator is verified against collected real-world experimental data and shows an 8% deviation. Parametric studies demonstrate the most influential parameters. We found that reducing the magnetic gradient from 1000 mT/m to 100 mT/m resulted in a decrease in recorded performance from 100% to 30.8%. Variation in fluid flow also had a considerable effect on the recorded performance, presenting a drop from 100% to 35.3% when fluid flow velocities increased from 0.005 m/s to 0.06 m/s. Changing the starting arrangement of particles resulted in a drop to 59% over the same range of fluid flow velocities. Full article

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18 pages, 5075 KiB

Open AccessArticle

Optimization of Setpoint Conditions for Enhanced Biofabrication of Silver Nanoparticles Using Helichrysum crispum Extracts

by Lebogang L. R. Mphahlele, Patrick T. Sekoai, Oluwatoyin Joseph Gbadeyan, Veshara Ramdas, Santosh Ramchuran, Viren Chunilall and Malusi Mkhize

Nanomaterials 2024, 14(23), 1916; https://doi.org/10.3390/nano14231916 - 28 Nov 2024

Abstract

This study investigated the optimization of setpoint conditions used for the enhanced biofabrication of silver nanoparticles (H.C-AgNPs) using Helichrysum crispum extracts. A Box–Behnken Design (BBD) model was used to evaluate the effects of reaction time, temperature, an H. crispum extraction volume, and a [...] Read more.

This study investigated the optimization of setpoint conditions used for the enhanced biofabrication of silver nanoparticles (H.C-AgNPs) using Helichrysum crispum extracts. A Box–Behnken Design (BBD) model was used to evaluate the effects of reaction time, temperature, an H. crispum extraction volume, and a 0.1 M AgNO₃ solution volume. A second-order polynomial regression equation was developed with a high R² of 0.9629, indicating that the model explained 96.29% of the variability in the data. The statistical significance of the model was confirmed with an F-value of 25.92 and a p-value of less than 0.0001. The optimal biofabrication conditions were determined to be a reaction time of 60 min, a temperature of 50 °C, an H. crispum extract volume of 10 mL, and a silver nitrate volume of 90 mL, achieving a peak absorbance of 3.007 a.u. The optimized conditions were experimentally validated, resulting in an absorbance of 3.386 a.u., reflecting a 12.6% increase. UV-Vis spectroscopy showed a distinct surface plasmon resonance (SPR) peak at 433 nm. XRD analysis confirmed a crystalline face-centered cubic (FCC) structure with a primary diffraction peak at 2θ = 38.44° (111 plane). SEM and EDS results confirmed a uniform size and high purity, while FTIR spectra confirmed the involvement of phytochemicals in nanoparticle stabilization. TEM analysis revealed a uniform particle size distribution with a mean size of 19.46 nm and a dispersity of 0.16%, respectively. These results demonstrate the importance of statistical tools in optimizing the setpoint conditions used in the biofabrication of AgNPs, which have applications in various fields. Full article

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