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16 pages, 5915 KiB

Open AccessArticle

Hierarchically Porous Carbon Microspheres Coated with MnO₂ Nanosheets as the Sulfur Host for High-Loading Lithium–Sulfur Batteries

by Liqin Dai, Zonglin Yi, Lijing Xie, Fangyuan Su, Xiaoqian Guo, Zhenbing Wang, Jiayao Cheng and Chengmeng Chen

Molecules 2024, 29(24), 5881; https://doi.org/10.3390/molecules29245881 - 13 Dec 2024

Viewed by 1064

Abstract

Lithium–sulfur (Li–S) batteries have emerged as a promising candidate for next-generation high-energy rechargeable lithium batteries, but their practical application is impeded by the sluggish redox kinetics and low sulfur loading. Here, we report the in situ growth of δ-MnO₂ nanosheets onto hierarchical [...] Read more.

Lithium–sulfur (Li–S) batteries have emerged as a promising candidate for next-generation high-energy rechargeable lithium batteries, but their practical application is impeded by the sluggish redox kinetics and low sulfur loading. Here, we report the in situ growth of δ-MnO₂ nanosheets onto hierarchical porous carbon microspheres (HPCs) to form an HPCs/S@MnO₂ composite for advanced lithium–sulfur batteries. The delicately designed hybrid architecture can effectively confine LiPSs and obtain high sulfur loading up to 10 mg cm⁻², in which the inner carbon microspheres with a large pore volume and large specific surface area can encapsulate high sulfur content, and the outer MnO₂ nanosheets, as a catalytic layer, can improve the conversion reaction of LiPSs and suppress the shuttle effect. The thick HPCs/S@MnO₂ electrode with 7 mg cm⁻² sulfur loading delivers an areal capacity of 4.0 mAh cm⁻² at 0.1 C and provides stable cycling stability with a low-capacity decay rate of 0.063 % per cycle after 200 cycles at 0.1 C. Furthermore, a Li–S pouch cell with a capacity of 2.5 A h is fabricated and demonstrates high cycling stability. This work offers a feasible method to build advanced sulfur electrodes with high areal loading and sheds light on their commercial application in high-performance Li–S batteries. Full article

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12 pages, 5135 KiB

Open AccessArticle

Hierarchically Developed Ni(OH)₂@MgCo₂O₄ Nanosheet Composites for Boosting Supercapacitor Performance

by Hammad Mueen Arbi, Ganesh Koyyada, Yedluri Anil Kumar, Dasha Kumar Kulurumotlakatla, Jae Hong Kim, Md Moniruzzaman, Salem Alzahmi and Ihab M. Obaidat

Nanomaterials 2023, 13(8), 1414; https://doi.org/10.3390/nano13081414 - 19 Apr 2023

Cited by 14 | Viewed by 2585

Abstract

MgCo₂O₄ nanomaterial is thought to be a promising candidate for renewable energy storage and conversions. Nevertheless, the poor stability performances and small specific areas of transition-metal oxides remain a challenge for supercapacitor (SC) device applications. In this study, sheet-like Ni(OH) [...] Read more.

MgCo₂O₄ nanomaterial is thought to be a promising candidate for renewable energy storage and conversions. Nevertheless, the poor stability performances and small specific areas of transition-metal oxides remain a challenge for supercapacitor (SC) device applications. In this study, sheet-like Ni(OH)₂@MgCo₂O₄ composites were hierarchically developed on nickel foam (NF) using the facile hydrothermal process with calcination technology, under carbonization reactions. The combination of the carbon–amorphous layer and porous Ni(OH)₂ nanoparticles was anticipated to enhance the stability performances and energy kinetics. The Ni(OH)₂@MgCo₂O₄ nanosheet composite achieved a superior specific capacitance of 1287 F g⁻¹ at a current value of 1 A g⁻¹, which is higher than that of pure Ni(OH)₂ nanoparticles and MgCo₂O₄ nanoflake samples. At a current density of 5 A g⁻¹, the Ni(OH)₂@MgCo₂O₄ nanosheet composite delivered an outstanding cycling stability of 85.6%, which it retained over 3500 long cycles with an excellent rate of capacity of 74.5% at 20 A g⁻¹. These outcomes indicate that such a Ni(OH)₂@MgCo₂O₄ nanosheet composite is a good contender as a novel battery-type electrode material for high-performance SCs. Full article

(This article belongs to the Special Issue Nanomaterials for Supercapacitors)

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17 pages, 10155 KiB

Open AccessArticle

Synthesis and Characterization of Porous MgO Nanosheet-Modified Activated Carbon Fiber Felt for Fluoride Adsorption

by De-Cai Wang, Min-Da Xu, Zhen Jin, Yi-Fan Xiao, Yang Chao, Jie Li, Shao-Hua Chen and Yi Ding

Nanomaterials 2023, 13(6), 1082; https://doi.org/10.3390/nano13061082 - 16 Mar 2023

Cited by 4 | Viewed by 2402

Abstract

In the present work, the porous MgO nanosheet-modified activated carbon fiber felt (MgO@ACFF) was prepared for fluoride removal. The MgO@ACFF was characterized by XRD, SEM, TEM, EDS, TG, and BET. The fluoride adsorption performance of MgO@ACFF also has been investigated. The adsorption rate [...] Read more.

In the present work, the porous MgO nanosheet-modified activated carbon fiber felt (MgO@ACFF) was prepared for fluoride removal. The MgO@ACFF was characterized by XRD, SEM, TEM, EDS, TG, and BET. The fluoride adsorption performance of MgO@ACFF also has been investigated. The adsorption rate of the MgO@ACFF toward fluoride is fast; more than 90% of the fluoride ions can be adsorbed within 100 min, and the adsorption kinetics of MgO@ACFF can be fitted in a pseudo-second-order model. The adsorption isotherm of MgO@ACFF fitted well in the Freundlich model. Additionally, the fluoride adsorption capacity of MgO@ACFF is larger than 212.2 mg/g at neutral. In a wide pH range of 2–10, the MgO@ACFF can efficiently remove fluoride from water, which is meaningful for practical usage. The effect of co-existing anions on the fluoride removal efficiency of the MgO@ACFF also has been studied. Furthermore, the fluoride adsorption mechanism of the MgO@ACFF was studied by the FTIR and XPS, and the results reveal a hydroxyl and carbonate co-exchange mechanism. The column test of the MgO@ACFF also has been investigated; 505-bed volumes of 5 mg/L fluoride solution can be treated with effluent under 1.0 mg/L. It is believed that the MgO@ACFF is a potential candidate for a fluoride adsorbent. Full article

(This article belongs to the Special Issue Nanomaterial Application in Environmental Monitoring and Water Treatment)

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28 pages, 7864 KiB

Open AccessArticle

Hierarchical Nanoflowers of MgFe₂O₄, Bentonite and B-,P- Co-Doped Graphene Oxide as Adsorbent and Photocatalyst: Optimization of Parameters by Box–Behnken Methodology

by Manpreet Kaur Ubhi, Manpreet Kaur, Dhanwinder Singh, Mohammed Javed, Aderbal C. Oliveira, Vijayendra Kumar Garg and Virender K. Sharma

Int. J. Mol. Sci. 2022, 23(17), 9678; https://doi.org/10.3390/ijms23179678 - 26 Aug 2022

Cited by 18 | Viewed by 2422

Abstract

In the present study, nanocomposites having hierarchical nanoflowers (HNFs) -like morphology were synthesized by ultra-sonication approach. HNFs were ternary composite of MgFe₂O₄ and bentonite with boron-, phosphorous- co-doped graphene oxide (BPGO). The HNFs were fully characterized using different analytical tools [...] Read more.

In the present study, nanocomposites having hierarchical nanoflowers (HNFs) -like morphology were synthesized by ultra-sonication approach. HNFs were ternary composite of MgFe₂O₄ and bentonite with boron-, phosphorous- co-doped graphene oxide (BPGO). The HNFs were fully characterized using different analytical tools viz. X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersion spectroscopy, transmission electron microscopy, X-ray diffraction, vibrating sample magnetometry and Mössbauer analysis. Transmission electron micrographs showed that chiffon-like BPGO nanosheets were wrapped on the MgFe₂O₄-bentonite surface, resulting in a porous flower-like morphology. The red-shift in XPS binding energies of HNFs as compared to MgFe₂O₄-bentoniteand BPGO revealed the presence of strong interactions between the two materials. Box–Behnken statistical methodology was employed to optimize adsorptive and photocatalytic parameters using Pb(II) and malathion as model pollutants, respectively. HNFs exhibited excellent adsorption ability for Pb(II) ions, with the Langmuir adsorption capacity of 654 mg g⁻¹ at optimized pH 6.0 and 96% photocatalytic degradation of malathion at pH 9.0 as compared to MgFe₂O₄-bentonite and BPGO. Results obtained in this study clearly indicate that HNFs are promising nanocomposite for the removal of inorganic and organic contaminants from the aqueous solutions. Full article

(This article belongs to the Section Molecular Nanoscience)

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12 pages, 4938 KiB

Open AccessArticle

Synthesis of a Novel 1D/2D Bi₂O₂CO₃–BiOI Heterostructure and Its Enhanced Photocatalytic Activity

by Yin Peng, Haozhi Qian, Nannan Zhao and Yuan Li

Catalysts 2021, 11(11), 1284; https://doi.org/10.3390/catal11111284 - 25 Oct 2021

Cited by 14 | Viewed by 2666

Abstract

A novel 1D/2D Bi₂O₂CO₃–BiOI heterojunction photocatalyst with high-quality interfaces was synthesized through a hydrothermal method by using Bi₂O₂CO₃ nanorods and KI as raw materials. Two-dimensional (2D) BiOI nanosheets uniformly and vertically grow [...] Read more.

A novel 1D/2D Bi₂O₂CO₃–BiOI heterojunction photocatalyst with high-quality interfaces was synthesized through a hydrothermal method by using Bi₂O₂CO₃ nanorods and KI as raw materials. Two-dimensional (2D) BiOI nanosheets uniformly and vertically grow on the 1D porous Bi₂O₂CO₃ rods. Bi₂O₂CO₃–BiOI heterojunctions exhibit better photocatalytic activity than pure Bi₂O₂CO₃ nanorods and BiOI nanosheets. Cr(VI) (30 mg/L), MO (20 mg/L) and BPA (20 mg/L) can be completely degraded in 8–15 min. The superior photocatalytic performance of 1D/2D Bi₂O₂CO₃–BiOI heterojunction is ascribed to the synergistic effects: (a) vertical 2D on 1D multidimensional structure; (b) the formation of the Bi₂O₂CO₃–BiOI p–n heterojunction; (c) high-quality interfaces between Bi₂O₂CO₃ and BiOI. Full article

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18 pages, 7902 KiB

Open AccessArticle

Superior Adsorption and Photocatalytic Degradation Capability of Mesoporous LaFeO₃/g-C₃N₄ for Removal of Oxytetracycline

by Ke Xu, Xiaosheng Yang, Luda Ruan, Shaolv Qi, Jianling Liu, Kaiyuan Liu, Shaoliang Pan, Guangwei Feng, Zeqin Dai, Xianjiong Yang, Rong Li and Jian Feng

Catalysts 2020, 10(3), 301; https://doi.org/10.3390/catal10030301 - 6 Mar 2020

Cited by 30 | Viewed by 3896

Abstract

Mesoporous LaFeO₃/g-C₃N₄ Z-scheme heterojunctions (LFC) were synthesized via the incorporation of LaFeO₃ nanoparticles and porous g-C₃N₄ ultrathin nanosheets. The as prepared LFC were characterized by transmission electron microscopy, scanning electron microscopy, atomic force microscopy, [...] Read more.

Mesoporous LaFeO₃/g-C₃N₄ Z-scheme heterojunctions (LFC) were synthesized via the incorporation of LaFeO₃ nanoparticles and porous g-C₃N₄ ultrathin nanosheets. The as prepared LFC were characterized by transmission electron microscopy, scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, powder X-ray diffraction, Raman spectra and N₂ adsorption analysis. The structural analysis indicated that the reheating process and the addition of NH₄Cl in the thermal polymerization were the key factors to get porous g-C₃N₄ ultrathin nanosheets and to obtain high specific surface areas of LFC. It remarkably enhanced the adsorption capacity and photocatalytic degradation of LFC for removal of oxytetracycline (OTC). The effect of the mass percentage of LaFeO₃ in LFC, pH and temperature on the OTC adsorption was investigated. The LaFeO₃/g-C₃N₄ heterojunction with 2 wt % LaFeO₃ (2-LFC) exhibited highest saturated adsorption capacity (101.67 mg g⁻¹) and largest photocatalytic degradation rate constant (1.35 L g⁻¹ min⁻¹), which was about 9 and 5 times higher than that of bulk g-C₃N₄ (CN), respectively. This work provided a facile method to prepare mesoporous LaFeO₃/g-C₃N₄ heterojunctions with especially well adsorption and photocatalytic activities for OTC, which can facilitate its practical applications in pollution control. Full article

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12 pages, 7315 KiB

Open AccessArticle

Highly Sensitive Acetone Gas Sensor Based on g-C₃N₄ Decorated MgFe₂O₄ Porous Microspheres Composites

by Run Zhang, Yan Wang, Zhanying Zhang and Jianliang Cao

Sensors 2018, 18(7), 2211; https://doi.org/10.3390/s18072211 - 10 Jul 2018

Cited by 65 | Viewed by 6773

Abstract

The g-C₃N₄ decorated magnesium ferrite (MgFe₂O₄) porous microspheres composites were successfully obtained via a one-step solvothermal method. The structure and morphology of the as-prepared MgFe₂O₄/g-C₃N₄ composites were characterized by [...] Read more.

The g-C₃N₄ decorated magnesium ferrite (MgFe₂O₄) porous microspheres composites were successfully obtained via a one-step solvothermal method. The structure and morphology of the as-prepared MgFe₂O₄/g-C₃N₄ composites were characterized by the techniques of X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermal gravity and differential scanning calorimeter (TG–DSC) and N₂-sorption. The gas sensing properties of the samples were measured and compared with a pure MgFe₂O₄-based sensor. The maximum response of the sensor based on MgFe₂O₄/g-C₃N₄ composites with 10 wt % g-C₃N₄ content to acetone is improved by about 145 times, while the optimum temperature was lowered by 60 °C. Moreover, the sensing mechanism and the reason for improving gas sensing performance were also discussed. Full article

(This article belongs to the Special Issue Advanced Nanomaterials based Gas Sensors)

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8 pages, 1696 KiB

Open AccessCommunication

Facile Synthesis of Two-Dimensional Porous MgCo₂O₄ Nanosheets as Anode for Lithium-Ion Batteries

by Fei Wang, Yong Liu, Yuanfang Zhao, Yue Wang, Zhijie Wang, Wanhong Zhang and Fengzhang Ren

Appl. Sci. 2018, 8(1), 22; https://doi.org/10.3390/app8010022 - 24 Dec 2017

Cited by 125 | Viewed by 8620

Abstract

Lithium-ion batteries (LIBs) have drawn considerable attention due to their high energy density and good cycling stability. As a transition-metal oxide, MgCo₂O₄ (MCO) is a promising candidate for energy storage applications because of its low-cost and environmental characteristics. Here, MCO [...] Read more.

Lithium-ion batteries (LIBs) have drawn considerable attention due to their high energy density and good cycling stability. As a transition-metal oxide, MgCo₂O₄ (MCO) is a promising candidate for energy storage applications because of its low-cost and environmental characteristics. Here, MCO porous nanosheets have been successfully synthesized by a microwave-assisted liquid phase method followed by an annealing procedure. As a result, MCO annealed at 600 °C exhibited optimal rate and cycling performances for Lithium storage application. Specifically, when tested as anode materials for Lithium ion batteries, MCO porous nanosheets delivered a high specific capacity of 1173.8 mAh g⁻¹ at 200 mA g⁻¹, and the specific capacity reached 1130.1 mAh g⁻¹ after 100 cycles at 200 mA g⁻¹, achieving 96.3% for the retention rate. The excellent electrochemical performances are mainly attributed to the monolayer porous nanosheet, which provides short transport paths for Li ions and electrons. Results demonstrated that the MCO porous nanosheets are promising electrode materials for Lithium ion batteries applications. Full article

(This article belongs to the Special Issue Electrode Materials for Lithium-ion Batteries/Super-capacitors)

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15 pages, 8654 KiB

Open AccessArticle

Hydrothermal Fabrication of High Specific Surface Area Mesoporous MgO with Excellent CO₂ Adsorption Potential at Intermediate Temperatures

by Wanlin Gao, Tuantuan Zhou, Benoit Louis and Qiang Wang

Catalysts 2017, 7(4), 116; https://doi.org/10.3390/catal7040116 - 15 Apr 2017

Cited by 50 | Viewed by 8732

Abstract

In this work, we report on a novel sodium dodecyl sulfate (SDS)-assisted magnesium oxide (MgO)-based porous adsorbent synthesized by hydrothermal method for intermediate CO₂ capture. For industrial MgO, its CO₂ adsorption capacity is normally less than 0.06 mmol g⁻¹, [...] Read more.

In this work, we report on a novel sodium dodecyl sulfate (SDS)-assisted magnesium oxide (MgO)-based porous adsorbent synthesized by hydrothermal method for intermediate CO₂ capture. For industrial MgO, its CO₂ adsorption capacity is normally less than 0.06 mmol g⁻¹, with a specific surface area as low as 25.1 m² g⁻¹. Herein, leaf-like MgO nanosheets which exhibited a disordered layer structure were fabricated by the introduction of SDS surfactants and the control of other synthesis parameters. This leaf-like MgO adsorbent showed an excellent CO₂ capacity of 0.96 mmol g⁻¹ at moderate temperatures (~300 °C), which is more than ten times higher than that of the commercial light MgO. This novel mesoporous MgO adsorbent also exhibited high stability during multiple CO₂ adsorption/desorption cycles. The excellent CO₂ capturing performance was believed to be related to its high specific surface area of 321.3 m² g⁻¹ and abundant surface active adsorption sites. This work suggested a new synthesis scheme for MgO based CO₂ adsorbents at intermediate temperatures, providing a competitive candidate for capturing CO₂ from certain sorption enhanced hydrogen production processes. Full article

(This article belongs to the Special Issue C1 Chemistry—C1-Platform Chemicals as Cornerstone for a Sustainable Energy)

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