Nanomaterials

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21 pages, 4583 KiB

Open AccessArticle

Highly Efficient Liquid-Phase Exfoliation of Layered Perovskite-like Titanates HLnTiO₄ and H₂Ln₂Ti₃O₁₀ (Ln = La, Nd) into Nanosheets

by Sergei A. Kurnosenko, Iana A. Minich, Oleg I. Silyukov and Irina A. Zvereva

Nanomaterials 2023, 13(23), 3052; https://doi.org/10.3390/nano13233052 - 29 Nov 2023

Viewed by 1096

Abstract

Nanosheets of layered perovskite-like oxides attract researchers as building blocks for the creation of a wide range of demanded nanomaterials. However, Ruddlesden–Popper phases are difficult to separate into nanosheets quantitatively via the conventional liquid-phase exfoliation procedure in aqueous solutions of bulky organic bases. [...] Read more.

Nanosheets of layered perovskite-like oxides attract researchers as building blocks for the creation of a wide range of demanded nanomaterials. However, Ruddlesden–Popper phases are difficult to separate into nanosheets quantitatively via the conventional liquid-phase exfoliation procedure in aqueous solutions of bulky organic bases. The present study has considered systematically a relatively novel and efficient approach to a high-yield preparation of concentrated suspensions of perovskite nanosheets. For this, the Ruddlesden–Popper titanates HLnTiO₄ and H₂Ln₂Ti₃O₁₀ (Ln = La, Nd) have been intercalated by n-alkylamines with various chain lengths, exposed to sonication in aqueous tetrabutylammonium hydroxide (TBAOH) and centrifuged to separate the nanosheet-containing supernatant. The experiments included variations of a wide range of conditions, which allowed for the achievement of impressive nanosheet concentrations in suspensions up to 2.1 g/L and yields up to 95%. The latter were found to strongly depend on the length of intercalated n-alkylamines. Despite the less expanded interlayer space, the titanates modified with short-chain amines demonstrated a much higher completeness of liquid-phase exfoliation as compared to those with long-chain ones. It was also shown that the exfoliation efficiency depends more on the sample stirring time in the TBAOH solution than on the sonication duration. Analysis of the titanate nanosheets obtained by means of dynamic light scattering, electron and atomic force microscopy revealed their lateral sizes of 30–250 nm and thickness of 2–4 nm. The investigated exfoliation strategy appears to be convenient for the high-yield production of perovskite nanosheet-based materials for photocatalytic hydrogen production, environmental remediation and other applications. Full article

(This article belongs to the Special Issue 2D and Carbon Nanomaterials for Energy Conversion and Storage)

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18 pages, 7447 KiB

Open AccessArticle

Green Synthesis of NiFe₂O₄ Nano-Spinel Oxide-Decorated Carbon Nanotubes for Efficient Capacitive Performance—Effect of Electrolyte Concentration

by Ali H. Bashal, Mahmoud A. Hefnawy, Hoda A. Ahmed, Mohamed A. El-Atawy, Rami Adel Pashameah and Shymaa S. Medany

Nanomaterials 2023, 13(19), 2643; https://doi.org/10.3390/nano13192643 - 26 Sep 2023

Cited by 7 | Viewed by 1247

Abstract

Energy storage applications received great attention due to environmental aspects. A green method was used to prepare a composite of nickel–iron-based spinel oxide nanoparticle@CNT. The prepared materials were characterized by different analytical methods like X-ray diffraction, X-ray photon spectroscopy (XPS), scanning electron microscopy [...] Read more.

Energy storage applications received great attention due to environmental aspects. A green method was used to prepare a composite of nickel–iron-based spinel oxide nanoparticle@CNT. The prepared materials were characterized by different analytical methods like X-ray diffraction, X-ray photon spectroscopy (XPS), scanning electron microscopy (SEM), and transmitted electron microscopy (TEM). The synergistic effect between nickel–iron oxide and carbon nanotubes was characterized using different electrochemical methods like cyclic voltammetry (CV), galvanostatic charging/discharging (GCD), and electrochemical impedance spectroscopy (EIS). The capacitances of the pristine NiFe₂O₄ and NiFe₂O₄@CNT were studied in different electrolyte concentrations. The effect of

{O H}^{-}

concentrations was studied for modified and non-modified surfaces. Furthermore, the specific capacitance was estimated for pristine and modified NiFe₂O₄ at a wide current range (5 to 17 A g⁻¹). Thus, the durability of different surfaces after 2000 cycles was studied, and the capacitance retention was estimated as 78.8 and 90.1% for pristine and modified NiFe₂O₄. On the other hand, the capacitance rate capability was observed as 65.1% (5 to 17 A g⁻¹) and 62.4% (5 to 17 A g⁻¹) for NiFe₂O₄ and NiFe₂O₄@CNT electrodes. Full article

(This article belongs to the Special Issue 2D and Carbon Nanomaterials for Energy Conversion and Storage)

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13 pages, 490 KiB

Open AccessArticle

Thermophase Seebeck Coefficient in Hybridized Superconductor-Quantum-Dot-Superconductor Josephson Junction Side-Coupled to Majorana Nanowire

by Yumei Gao, Xiaoyan Zhang, Zichuan Yi, Liming Liu and Feng Chi

Nanomaterials 2023, 13(17), 2489; https://doi.org/10.3390/nano13172489 - 04 Sep 2023

Viewed by 770

Abstract

The dc Josephson current is generated from phase difference between two superconductors separated by a mesoscopic thin film (Josephson junction) without external bias voltage. In the presence of a temperature gradient across the superconductors, a thermal phase is induced under the condition of [...] Read more.

The dc Josephson current is generated from phase difference between two superconductors separated by a mesoscopic thin film (Josephson junction) without external bias voltage. In the presence of a temperature gradient across the superconductors, a thermal phase is induced under the condition of open circuit. This is very similar to the Seebeck effect in the usual thermoelectric effect, and the thermal phase is thus named as thermophase Seebeck coefficient (TPSC). Here we find obvious enhancement and sign change of the TPSC unique to the Josephson junction composing of two superconductors connected to a semiconductor quantum dot (QD), which is additionally side-coupled to a nanowire hosting Majorana bound states (MBSs), the system denoted by S-MQD-S. These result arise from the newly developed states near the Fermi level of the superconductors due to the QD-MBS hybridization when the dot level is within the superconducting gap. The sign change of the TPSC provides a strong evidence of the existence of MBSs, and is absent if the QD is coupled to regular fermion, such as another QD (system denoted by S-DQD-S). We show that the magnitude and sign of the TPSC are sensitive to the physical quantities including interaction strength between the QD and MBSs, direct overlap between the MBSs, system equilibrium temperature, as well as hopping amplitude between the QD and the superconductors. The obtained results are explained with the help of the current-carrying density of the states (CCDOS), and may be useful in interdisciplinary research areas of Josephson and Majorana physics. Full article

(This article belongs to the Special Issue 2D and Carbon Nanomaterials for Energy Conversion and Storage)

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22 pages, 4063 KiB

Open AccessArticle

The Influence of Reduced Graphene Oxide on the Texture and Chemistry of N,S-Doped Porous Carbon. Implications for Electrocatalytic and Energy Storage Applications

by Samantha K. Samaniego Andrade, Shiva Shankar Lakshmi, István Bakos, Szilvia Klébert, Robert Kun, Miklós Mohai, Balázs Nagy and Krisztina László

Nanomaterials 2023, 13(16), 2364; https://doi.org/10.3390/nano13162364 - 18 Aug 2023

Cited by 1 | Viewed by 1272

Abstract

In this work, we study the influence of reduced graphene oxide (rGO) on the morphology and chemistry of highly porous N,S-doped carbon cryogels. Simultaneously, we propose an easily upscalable route to prepare such carbons by adding graphene oxide (GO) in as-received suspended form [...] Read more.

In this work, we study the influence of reduced graphene oxide (rGO) on the morphology and chemistry of highly porous N,S-doped carbon cryogels. Simultaneously, we propose an easily upscalable route to prepare such carbons by adding graphene oxide (GO) in as-received suspended form to the aqueous solution of the ι-carrageenan and urea precursors. First, 1.25–5 wt% GO was incorporated into the dual-doped polymer matrix. The CO₂, CO, and H₂O emitted during the thermal treatments resulted in the multifaceted modification of the textural and chemical properties of the porous carbon. This facilitated the formation of micropores through self-activation and resulted in a substantial increase in the apparent surface area (up to 1780 m²/g) and pore volume (up to 1.72 cm³/g). However, adding 5 wt% GO led to overactivation. The incorporated rGO has an ordering effect on the carbon matrix. The evolving oxidative species influence the surface chemistry in a complex way, but sufficient N and S atoms (ca. 4 and >1 at%, respectively) were preserved in addition to the large number of developing defects. Despite the complexity of the textural and chemical changes, rGO increased the electrical conductivity monotonically. In alkaline oxygen reduction reaction (ORR) tests, the sample with 1.25 wt% GO exhibited a 4e⁻ mechanism and reasonable stability, but a higher rGO content gradually compromised the performance of the electrodes. The sample containing 5 wt% GO was the most sensitive under oxidative conditions, but after stabilization it exhibited the highest gravimetric capacitance. In Li-ion battery tests, the coulombic efficiency of all the samples was consistently above 98%, indicating the high potential of these carbons for efficient Li-ion insertion and reinsertion during the charge–discharge process, thereby providing a promising alternative for graphite-based anodes. The cell from the 1.25 wt% GO sample showed an initial discharge capacity of 313 mAh/g, 95.1% capacity retention, and 99.3% coulombic efficiency after 50 charge–discharge cycles. Full article

(This article belongs to the Special Issue 2D and Carbon Nanomaterials for Energy Conversion and Storage)

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12 pages, 4960 KiB

Open AccessFeature PaperArticle

High Thermoelectric Performance of a Novel γ-PbSnX₂ (X = S, Se, Te) Monolayer: Predicted Using First Principles

by Changhao Ding, Zhifu Duan, Nannan Luo, Jiang Zeng, Wei Ren, Liming Tang and Keqiu Chen

Nanomaterials 2023, 13(9), 1519; https://doi.org/10.3390/nano13091519 - 29 Apr 2023

Cited by 1 | Viewed by 1490

Abstract

Two-dimensional (2D) group IV metal chalcogenides are potential candidates for thermoelectric (TE) applications due to their unique structural properties. In this paper, we predicted a 2D monolayer group IV metal chalcogenide semiconductor

γ

-PbSn₂ (X = S, Se, Te), and first-principles calculations [...] Read more.

Two-dimensional (2D) group IV metal chalcogenides are potential candidates for thermoelectric (TE) applications due to their unique structural properties. In this paper, we predicted a 2D monolayer group IV metal chalcogenide semiconductor

γ

-PbSn₂ (X = S, Se, Te), and first-principles calculations and Boltzmann transport theory were used to study the thermoelectric performance. We found that

γ

-PbSnX₂ had an ultra-high carrier mobility of up to 4.04 × 10³ cm² V⁻¹ s⁻¹, which produced metal-like electrical conductivity. Moreover,

γ

-PbSn₂ not only has a very high Seebeck coefficient, which leads to a high power factor, but also shows an intrinsically low lattice thermal conductivity of 6–8 W/mK at room temperature. The lower lattice thermal conductivity and high power factors resulted in excellent thermoelectric performance. The

Z T

values of

γ

-PbSnS₂ and

γ

-PbSnSe₂ were as high as 2.65 and 2.96 at 900 K, respectively. The result suggests that the

γ

-PbSnX₂ monolayer is a better candidates for excellent thermoelectric performance. Full article

(This article belongs to the Special Issue 2D and Carbon Nanomaterials for Energy Conversion and Storage)

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14 pages, 6909 KiB

Open AccessArticle

The Effects of Ultrasound Treatment of Graphite on the Reversibility of the (De)Intercalation of an Anion from Aqueous Electrolyte Solution

by Ghulam Abbas, Zahid Ali Zafar, Farjana J. Sonia, Karel Knížek, Jana Houdková, Petr Jiříček, Martin Kalbáč, Jiří Červenka and Otakar Frank

Nanomaterials 2022, 12(22), 3932; https://doi.org/10.3390/nano12223932 - 08 Nov 2022

Cited by 1 | Viewed by 1785

Abstract

Low cycling stability is one of the most crucial issues in rechargeable batteries. Herein, we study the effects of a simple ultrasound treatment of graphite for the reversible (de)intercalation of a ClO₄⁻ anion from a 2.4 M Al(ClO₄)₃ [...] Read more.

Low cycling stability is one of the most crucial issues in rechargeable batteries. Herein, we study the effects of a simple ultrasound treatment of graphite for the reversible (de)intercalation of a ClO₄⁻ anion from a 2.4 M Al(ClO₄)₃ aqueous solution. We demonstrate that the ultrasound-treated graphite offers the improved reversibility of the ClO₄⁻ anion (de)intercalation compared with the untreated samples. The ex situ and in situ Raman spectroelectrochemistry and X-ray diffraction analysis of the ultrasound-treated materials shows no change in the interlayer spacing, a mild increase in the stacking order, and a large increase in the amount of defects in the lattice accompanied by a decrease in the lateral crystallite size. The smaller flakes of the ultrasonicated natural graphite facilitate the improved reversibility of the ClO₄⁻ anion electrochemical (de)intercalation and a more stable electrochemical performance with a cycle life of over 300 cycles. Full article

(This article belongs to the Special Issue 2D and Carbon Nanomaterials for Energy Conversion and Storage)

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14 pages, 21829 KiB

Open AccessArticle

Nanostructure Engineering via Intramolecular Construction of Carbon Nitride as Efficient Photocatalyst for CO₂ Reduction

by Muhammad Sohail, Tariq Altalhi, Abdullah G. Al-Sehemi, Taha Abdel Mohaymen Taha, Karam S. El-Nasser, Ahmed A. Al-Ghamdi, Mahnoor Boukhari, Arkom Palamanit, Asif Hayat, Mohammed A. Amin and Wan Izhan Nawawi Bin Wan Ismail

Nanomaterials 2021, 11(12), 3245; https://doi.org/10.3390/nano11123245 - 29 Nov 2021

Cited by 32 | Viewed by 2355

Abstract

Light-driven heterogeneous photocatalysis has gained great significance for generating solar fuel; the challenging charge separation process and sluggish surface catalytic reactions significantly restrict the progress of solar energy conversion using a semiconductor photocatalyst. Herein, we propose a novel and feasible strategy to incorporate [...] Read more.

Light-driven heterogeneous photocatalysis has gained great significance for generating solar fuel; the challenging charge separation process and sluggish surface catalytic reactions significantly restrict the progress of solar energy conversion using a semiconductor photocatalyst. Herein, we propose a novel and feasible strategy to incorporate dihydroxy benzene (DHB) as a conjugated monomer within the framework of urea containing CN (CNU-DHBx) to tune the electronic conductivity and charge separation due to the aromaticity of the benzene ring, which acts as an electron-donating species. Systematic characterizations such as SPV, PL, XPS, DRS, and TRPL demonstrated that the incorporation of the DHB monomer greatly enhanced the photocatalytic CO₂ reduction of CN due to the enhanced charge separation and modulation of the ionic mobility. The significantly enhanced photocatalytic activity of CNU–DHB_15.0 in comparison with parental CN was 85 µmol/h for CO and 19.92 µmol/h of the H₂ source. It can be attributed to the electron–hole pair separation and enhance the optical adsorption due to the presence of DHB. Furthermore, this remarkable modification affected the chemical composition, bandgap, and surface area, encouraging the controlled detachment of light-produced photons and making it the ideal choice for CO₂ photoreduction. Our research findings potentially offer a solution for tuning complex charge separation and catalytic reactions in photocatalysis that could practically lead to the generation of artificial photocatalysts for efficient solar energy into chemical energy conversion. Full article

(This article belongs to the Special Issue 2D and Carbon Nanomaterials for Energy Conversion and Storage)

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Review

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26 pages, 3595 KiB

Open AccessEditor’s ChoiceReview

A Comprehensive Review on Electrocatalytic Applications of 2D Metallenes

by Mohamed A. Basyooni-M. Kabatas

Nanomaterials 2023, 13(22), 2966; https://doi.org/10.3390/nano13222966 - 17 Nov 2023

Cited by 1 | Viewed by 1104

Abstract

This review introduces metallenes, a cutting-edge form of atomically thin two-dimensional (2D) metals, gaining attention in energy and catalysis. Their unique physicochemical and electronic properties make them promising for applications like catalysis. Metallenes stand out due to their abundance of under-coordinated metal atoms, [...] Read more.

This review introduces metallenes, a cutting-edge form of atomically thin two-dimensional (2D) metals, gaining attention in energy and catalysis. Their unique physicochemical and electronic properties make them promising for applications like catalysis. Metallenes stand out due to their abundance of under-coordinated metal atoms, enhancing the catalytic potential by improving atomic utilization and intrinsic activity. This review explores the utility of 2D metals as electrocatalysts in sustainable energy conversion, focusing on the Oxygen Evolution Reaction, Oxygen Reduction Reaction, Fuel Oxidation Reaction, and Carbon Dioxide Reduction Reaction. Aimed at researchers in nanomaterials and energy, the review is a comprehensive resource for unlocking the potential of 2D metals in creating a sustainable energy landscape. Full article

(This article belongs to the Special Issue 2D and Carbon Nanomaterials for Energy Conversion and Storage)

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26 pages, 8951 KiB

Open AccessReview

A Review of Yarn-Based One-Dimensional Supercapacitors

by Duri Han, Minju Kim, Sojung Lee and Changsoon Choi

Nanomaterials 2023, 13(18), 2581; https://doi.org/10.3390/nano13182581 - 18 Sep 2023

Cited by 1 | Viewed by 1145

Abstract

Energy storage in a one-dimensional format is increasingly vital for the functionality of wearable technologies and is garnering attention from various sectors, such as smart apparel, the Internet of Things, e-vehicles, and robotics. Yarn-based supercapacitors are a particularly compelling solution for wearable energy [...] Read more.

Energy storage in a one-dimensional format is increasingly vital for the functionality of wearable technologies and is garnering attention from various sectors, such as smart apparel, the Internet of Things, e-vehicles, and robotics. Yarn-based supercapacitors are a particularly compelling solution for wearable energy reserves owing to their high power densities and adaptability to the human form. Furthermore, these supercapacitors can be seamlessly integrated into textile fabrics for practical utility across various types of clothing. The present review highlights the most recent innovations and research directions related to yarn-based supercapacitors. Initially, we explore different types of electrodes and active materials, ranging from carbon-based nanomaterials to metal oxides and conductive polymers, that are being used to optimize electrochemical capacitance. Subsequently, we survey different methodologies for loading these active materials onto yarn electrodes and summarize innovations in stretchable yarn designs, such as coiling and buckling. Finally, we outline a few pressing research challenges and future research directions in this field. Full article

(This article belongs to the Special Issue 2D and Carbon Nanomaterials for Energy Conversion and Storage)

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