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13 pages, 4216 KiB

Open AccessArticle

NiMoO₄ Nanosheets Embedded in Microflake-Assembled CuCo₂O₄ Island-like Structure on Ni Foam for High-Performance Asymmetrical Solid-State Supercapacitors

by Gaofeng Li, Lingling Chen and Longfei Li

Molecules 2023, 28(19), 6840; https://doi.org/10.3390/molecules28196840 - 28 Sep 2023

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Abstract

Micro/nano-heterostructure with subtle structural design is an effective strategy to reduce the self-aggregation of 2D structure and maintain a large specific surface area to achieve high-performance supercapacitors. Herein, we report a rationally designed micro/nano-heterostructure of complex ternary transition metal oxides (TMOs) by a [...] Read more.

Micro/nano-heterostructure with subtle structural design is an effective strategy to reduce the self-aggregation of 2D structure and maintain a large specific surface area to achieve high-performance supercapacitors. Herein, we report a rationally designed micro/nano-heterostructure of complex ternary transition metal oxides (TMOs) by a two-step hydrothermal method. Microflake-assembled island-like CuCo₂O₄ frameworks and secondary inserted units of NiMoO₄ nanosheets endow CuCo₂O₄/NiMoO₄ composites with desired micro/nanostructure features. Three-dimensional architectures constructed from CuCo₂O₄ microflakes offer a robust skeleton to endure structural change during cycling and provide efficient and rapid pathways for ion and electron transport. Two-dimensional NiMoO₄ nanosheets possess numerous active sites and multi-access ion paths. Benefiting from above-mentioned advantages, the CuCo₂O₄/NiMoO₄ heterostructures exhibit superior pseudocapacitive performance with a high specific capacitance of 2350 F/g at 1 A/g as well as an excellent cycling stability of 91.5% over 5000 cycles. A solid-state asymmetric supercapacitor based on the CuCo₂O₄/NiMoO₄ electrode as a positive electrode and activated carbon as a negative electrode achieves a high energy density of 51.7 Wh/kg at a power density of 853.7 W/kg. These results indicate that the hybrid micro/nanostructured TMOs will be promising for high-performance supercapacitors. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion)

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12 pages, 3426 KiB

Open AccessArticle

GeO₂ Nanoparticles Decorated in Amorphous Carbon Nanofiber Framework as Highly Reversible Lithium Storage Anode

by Wenhe Xie, Congcong Liu, Chen Hu, Yuanxiao Ma, Xuefeng Li, Qian Wang, Zhe An, Shenghong Liu, Haibin Sun and Xiaolei Sun

Molecules 2023, 28(18), 6730; https://doi.org/10.3390/molecules28186730 - 21 Sep 2023

Cited by 1 | Viewed by 892

Abstract

Germanium oxide (GeO₂) is a high theoretical capacity electrode material due to its alloying and conversion reaction. However, the actual cycling capacity is rather poor on account of suffering low electron/ion conductivity, enormous volume change and agglomeration in the repeated lithiation/delithiation [...] Read more.

Germanium oxide (GeO₂) is a high theoretical capacity electrode material due to its alloying and conversion reaction. However, the actual cycling capacity is rather poor on account of suffering low electron/ion conductivity, enormous volume change and agglomeration in the repeated lithiation/delithiation process, which renders quite a low reversible electrochemical lithium storage reaction. In this work, highly amorphous GeO₂ particles are uniformly distributed in the carbon nanofiber framework, and the amorphous carbon nanofiber not only improves the conduction and buffers the volume changes but also prevents active material agglomeration. As a result, the present GeO₂ and carbon composite electrode exhibits highly reversible alloying and conversion processes during the whole cycling process. The two reversible electrochemical reactions are verified by differential capacity curves and cyclic voltammetry measurements during the whole cycling process. The corresponding reversible capacity is 747 mAh g⁻¹ after 300 cycles at a current density of 0.3 A g⁻¹. The related reversible capacities are 933, 672, 487 and 302 mAh g⁻¹ at current densities of 0.2, 0.4, 0.8 and 1.6 A g⁻¹, respectively. The simple strategy for the design of amorphous GeO₂/carbon composites enables potential application for high-performance LIBs. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion)

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15 pages, 4950 KiB

Open AccessArticle

In Situ N, O Co-Doped Nanoporous Carbon Derived from Mixed Egg and Rice Waste as Green Supercapacitor

by Shumeng Qin, Peiliang Liu, Jieni Wang, Chenxiao Liu, Shuqin Zhang, Yijun Tian, Fangfang Zhang, Lin Wang, Leichang Cao, Jinglai Zhang and Shicheng Zhang

Molecules 2023, 28(18), 6543; https://doi.org/10.3390/molecules28186543 - 09 Sep 2023

Cited by 1 | Viewed by 809

Abstract

The conversion of nitrogen–oxygen-rich biomass wastes into heteroatomic co-doped nanostructured carbons used as energy storage materials has received widespread attention. In this study, an in situ nitrogen–oxygen co-doped porous carbon was prepared for supercapacitor applications via a two-step method of pre-carbonization and pyrolytic [...] Read more.

The conversion of nitrogen–oxygen-rich biomass wastes into heteroatomic co-doped nanostructured carbons used as energy storage materials has received widespread attention. In this study, an in situ nitrogen–oxygen co-doped porous carbon was prepared for supercapacitor applications via a two-step method of pre-carbonization and pyrolytic activation using mixed egg yolk/white and rice waste. The optimal sample (YPAC-1) was found to have a 3D honeycomb structure composed of abundant micropores and mesopores with a high specific surface area of 1572.1 m² g⁻¹, which provided abundant storage space and a wide transport path for electrolyte ions. Notably, the specific capacitance of the constructed three-electrode system was as high as 446.22 F g⁻¹ at a current density of 1 A g⁻¹ and remained above 50% at 10 A g⁻¹. The capacitance retention was 82.26% after up to 10,000 cycles. The symmetrical capacitor based on YPAC-1 with a two-electrode structure exhibited an energy density of 8.3 Wh kg⁻¹ when the power density was 136 W kg⁻¹. These results indicate that porous carbon materials prepared from mixed protein and carbohydrate waste have promising applications in the field of supercapacitors. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion)

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13 pages, 2941 KiB

Open AccessArticle

Phosphate-Induced Reaction to Prepare Coal-Based P-Doped Hard Carbon with a Hierarchical Porous Structure for Improved Sodium-Ion Storage

by Limin Deng, Yakun Tang, Jingmei Liu, Yue Zhang, Wenjun Song, Yuandong Li and Lang Liu

Molecules 2023, 28(13), 4921; https://doi.org/10.3390/molecules28134921 - 22 Jun 2023

Cited by 1 | Viewed by 1208

Abstract

The use of coal as a precursor for producing hard carbon is favored due to its abundance, low cost, and high carbon yield. To further optimize the sodium storage performance of hard carbon, the introduction of heteroatoms has been shown to be an [...] Read more.

The use of coal as a precursor for producing hard carbon is favored due to its abundance, low cost, and high carbon yield. To further optimize the sodium storage performance of hard carbon, the introduction of heteroatoms has been shown to be an effective approach. However, the inert structure in coal limits the development of heteroatom-doped coal-based hard carbon. Herein, coal-based P-doped hard carbon was synthesized using Ca₃(PO₄)₂ to achieve homogeneous phosphorus doping and inhibit carbon microcrystal development during high-temperature carbonization. This involved a carbon dissolution reaction where Ca₃(PO₄)₂ reacted with SiO₂ and carbon in coal to form phosphorus and CO. The resulting hierarchical porous structure allowed for rapid diffusion of Na⁺ and resulted in a high reversible capacity of 200 mAh g⁻¹ when used as an anode material for Na⁺ storage. Compared to unpretreated coal-based hard carbon, the P-doped hard carbon displayed a larger initial coulombic efficiency (64%) and proportion of plateau capacity (47%), whereas the unpretreated carbon only exhibited an initial coulombic efficiency of 43.1% and a proportion of plateau capacity of 29.8%. This work provides a green, scalable approach for effective microcrystalline regulation of hard carbon from low-cost and highly aromatic precursors. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion)

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12 pages, 1924 KiB

Open AccessArticle

Activated Carbon Derived from Waste Oil Shale Semi-Coke for Supercapacitor Application

by Chu’an Xiong, Nan Wang and Mai Feng

Molecules 2023, 28(12), 4804; https://doi.org/10.3390/molecules28124804 - 16 Jun 2023

Cited by 1 | Viewed by 1332

Abstract

As fossil fuels gradually deplete, oil shale, one of the world’s largest energy resources, has attracted much attention. Oil shale semi-coke (OSS) is the main byproduct of oil shale pyrolysis, which is produced in large quantities and causes severe environmental pollution. Therefore, there [...] Read more.

As fossil fuels gradually deplete, oil shale, one of the world’s largest energy resources, has attracted much attention. Oil shale semi-coke (OSS) is the main byproduct of oil shale pyrolysis, which is produced in large quantities and causes severe environmental pollution. Therefore, there is an urgent need to explore a method suitable for the sustainable and effective utilization of OSS. In this study, OSS was used to prepare activated carbon by microwave-assisted separation and chemical activation, which was then applied in the field of supercapacitors. Raman, XRD, FT-IR, TEM, and nitrogen adsorption–desorption were adopted to characterize activated carbon. The results showed that ACF activated with FeCl₃-ZnCl₂/carbon as a precursor has larger specific surface area, suitable pore size, and higher degree of graphitization compared with the materials prepared by other activation methods. The electrochemical properties of several active carbon materials were also evaluated by CV, GCD, and EIS measurements. The specific surface area of ACF is 1478 m² g⁻¹, when the current density is 1 A g⁻¹, the specific capacitance is 185.0 F g⁻¹. After 5000 cycles of testing, the capacitance retention rate was as high as 99.5%, which is expected to provide a new strategy of converting waste products to low-cost activated carbon materials for high-performance supercapacitors. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion)

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13 pages, 3177 KiB

Open AccessArticle

Fe-Incorporated Nickel-Based Bimetallic Metal–Organic Frameworks for Enhanced Electrochemical Oxygen Evolution

by Dan Wang, Fuhe Le, Jing Lv, Xue Yang, Xianhao Chen, Haibin Yao and Wei Jia

Molecules 2023, 28(11), 4366; https://doi.org/10.3390/molecules28114366 - 26 May 2023

Cited by 1 | Viewed by 1150

Abstract

Developing cost-effective and high-efficiency catalysts for electrocatalytic oxygen evolution reaction (OER) is crucial for energy conversions. Herein, a series of bimetallic NiFe metal–organic frameworks (NiFe-BDC) were prepared by a simple solvothermal method for alkaline OER. The synergistic effect between Ni and Fe as [...] Read more.

Developing cost-effective and high-efficiency catalysts for electrocatalytic oxygen evolution reaction (OER) is crucial for energy conversions. Herein, a series of bimetallic NiFe metal–organic frameworks (NiFe-BDC) were prepared by a simple solvothermal method for alkaline OER. The synergistic effect between Ni and Fe as well as the large specific surface area lead to a high exposure of Ni active sites during the OER. The optimized NiFe-BDC-0.5 exhibits superior OER performances with a small overpotential of 256 mV at a current density of 10 mA cm⁻² and a low Tafel slope of 45.4 mV dec⁻¹, which outperforms commercial RuO₂ and most of the reported MOF-based catalysts reported in the literature. This work provides a new insight into the design of bimetallic MOFs in the applications of electrolysis. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion)

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15 pages, 4505 KiB

Open AccessArticle

Zinc-Mediated Template Synthesis of Hierarchical Porous N-Doped Carbon Electrocatalysts for Efficient Oxygen Reduction

by Qianhui Ma, Guifa Long, Xulei Tang, Xiaobao Li, Xianghui Wang, Chenghang You, Wenjun Fan and Qingqing Wang

Molecules 2023, 28(11), 4257; https://doi.org/10.3390/molecules28114257 - 23 May 2023

Cited by 1 | Viewed by 1178

Abstract

The development of highly active and low-cost catalysts for use in oxygen reduction reaction (ORR) is crucial to many advanced and eco-friendly energy techniques. N-doped carbons are promising ORR catalysts. However, their performance is still limited. In this work, a zinc-mediated template synthesis [...] Read more.

The development of highly active and low-cost catalysts for use in oxygen reduction reaction (ORR) is crucial to many advanced and eco-friendly energy techniques. N-doped carbons are promising ORR catalysts. However, their performance is still limited. In this work, a zinc-mediated template synthesis strategy for the development of a highly active ORR catalyst with hierarchical porous structures was presented. The optimal catalyst exhibited high ORR performance in a 0.1 M KOH solution, with a half-wave potential of 0.89 V vs. RHE. Additionally, the catalyst exhibited excellent methanol tolerance and stability. After a 20,000 s continuous operation, no obvious performance decay was observed. When used as the air–electrode catalyst in a zinc–air battery (ZAB), it delivered an outstanding discharging performance, with peak power density and specific capacity as high as 196.3 mW cm⁻² and 811.5 mAh g_Zn⁻¹, respectively. Its high performance and stability endow it with potential in practical and commercial applications as a highly active ORR catalyst. Additionally, it is believed that the presented strategy can be applied to the rational design and fabrication of highly active and stable ORR catalysts for use in eco-friendly and future-oriented energy techniques. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion)

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11 pages, 6653 KiB

Open AccessArticle

The Solid-State Synthesis of BiOIO₃ Nanoplates with Boosted Photocatalytic Degradation Ability for Organic Contaminants

by Jia Li, Jing Xie, Xiaojing Zhang, Enhui Lu and Yali Cao

Molecules 2023, 28(9), 3681; https://doi.org/10.3390/molecules28093681 - 24 Apr 2023

Cited by 1 | Viewed by 1172

Abstract

BiOIO₃ exhibits excellent oxidation capacity in the photocatalytic degradation of contaminants thanks to its unique polarized electric and internal electrostatic field. However, the synthetic method of BiOIO₃ nanomaterials is mainly focused on hydrothermal technology, owing to its high energy consumption and [...] Read more.

BiOIO₃ exhibits excellent oxidation capacity in the photocatalytic degradation of contaminants thanks to its unique polarized electric and internal electrostatic field. However, the synthetic method of BiOIO₃ nanomaterials is mainly focused on hydrothermal technology, owing to its high energy consumption and time-consuming nature. In this work, a BiOIO₃ nanosheet was prepared by a simple solid-state chemical reaction, which was identified by XRD, EDS, XPS, and HRTEM. Benefiting from the strong oxidation ability of the valence band maximum, the distinctive layer structure, and the promoted generation of ·O₂⁻, the BiOIO₃ nanosheet exhibits excellent photo-degradation activity for methyl orange (MO) and its apparent rate constant is 0.2179 min⁻¹, which is about 3.02, 8.60, and 10.26 times higher than that of P25, BiOCl, and Bi₂O₂CO₃, respectively. Interestingly, the BiOIO₃ nanosheet also has good photocatalytic degradation performance for phenolic compounds; in particular, the degradation rate of BPA can reach 96.5% after 16 min, mainly due to hydroxylation reaction. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion)

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12 pages, 4120 KiB

Open AccessArticle

Nitrogen-Doped Hierarchical Porous Carbon Derived from Coal for High-Performance Supercapacitor

by Leiming Cai, Yanzhe Zhang, Rui Ma, Xia Feng, Lihua Yan, Dianzeng Jia, Mengjiao Xu, Lili Ai, Nannan Guo and Luxiang Wang

Molecules 2023, 28(9), 3660; https://doi.org/10.3390/molecules28093660 - 23 Apr 2023

Cited by 3 | Viewed by 1630

Abstract

The surface properties and the hierarchical pore structure of carbon materials are important for their actual application in supercapacitors. It is important to pursue an integrated approach that is both easy and cost-effective but also challenging. Herein, coal-based hierarchical porous carbon with nitrogen [...] Read more.

The surface properties and the hierarchical pore structure of carbon materials are important for their actual application in supercapacitors. It is important to pursue an integrated approach that is both easy and cost-effective but also challenging. Herein, coal-based hierarchical porous carbon with nitrogen doping was prepared by a simple dual template strategy using coal as the carbon precursor. The hierarchical pores were controlled by incorporating different target templates. Thanks to high conductivity, large electrochemically active surface area (483 m² g⁻¹), hierarchical porousness with appropriate micro-/mesoporous channels, and high surface nitrogen content (5.34%), the resulting porous carbon exhibits a high specific capacitance in a three-electrode system using KOH electrolytes, reaching 302 F g⁻¹ at 1 A g⁻¹ and 230 F g⁻¹ at 50 A g⁻¹ with a retention rate of 76%. At 250 W kg⁻¹, the symmetrical supercapacitor assembled at 6 M KOH shows a high energy density of 8.3 Wh kg^−1, and the stability of the cycling is smooth. The energy density of the symmetric supercapacitor assembled under ionic liquids was further increased to 48.3 Wh kg⁻¹ with a power output of 750 W kg⁻¹ when the operating voltage was increased to 3 V. This work expands the application of coal-based carbon materials in capacitive energy storage. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion)

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17 pages, 5204 KiB

Open AccessArticle

Constructing Molybdenum Phosphide@Cobalt Phosphide Heterostructure Nanoarrays on Nickel Foam as a Bifunctional Electrocatalyst for Enhanced Overall Water Splitting

by Yingchun Huang, Hongming Chen and Busheng Zhang

Molecules 2023, 28(9), 3647; https://doi.org/10.3390/molecules28093647 - 22 Apr 2023

Cited by 2 | Viewed by 1675

Abstract

The construction of multi-level heterostructure materials is an effective way to further the catalytic activity of catalysts. Here, we assembled self-supporting MoS₂@Co precursor nanoarrays on the support of nickel foam by coupling the hydrothermal method and electrostatic adsorption method, followed by [...] Read more.

The construction of multi-level heterostructure materials is an effective way to further the catalytic activity of catalysts. Here, we assembled self-supporting MoS₂@Co precursor nanoarrays on the support of nickel foam by coupling the hydrothermal method and electrostatic adsorption method, followed by a low-temperature phosphating strategy to obtain Mo₄P₃@CoP/NF electrode materials. The construction of the Mo₄P₃@CoP heterojunction can lead to electron transfer from the Mo₄P₃ phase to the CoP phase at the phase interface region, thereby optimizing the charge structure of the active sites. Not only that, the introduction of Mo₄P₃ will make water molecules preferentially adsorb on its surface, which will help to reduce the water molecule decomposition energy barrier of the Mo₄P₃@CoP heterojunction. Subsequently, H* overflowed to the surface of CoP to generate H₂ molecules, which finally showed a lower water molecule decomposition energy barrier and better intermediate adsorption energy. Based on this, the material shows excellent HER/OER dual-functional catalytic performance under alkaline conditions. It only needs 72 mV and 238 mV to reach 10 mA/cm² for HER and OER, respectively. Meanwhile, in a two-electrode system, only 1.54 V is needed to reach 10 mA/cm², which is even better than the commercial RuO₂/NF||Pt/C/NF electrode pair. In addition, the unique self-supporting structure design ensures unimpeded electron transmission between the loaded nanoarray and the conductive substrate. The loose porous surface design is not only conducive to the full exposure of more catalytic sites on the surface but also facilitates the smooth escape of gas after production so as to improve the utilization rate of active sites. This work has important guiding significance for the design and development of high-performance bifunctional electrolytic water catalysts. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion)

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14 pages, 6924 KiB

Open AccessArticle

Modulating the Graphitic Domains and Pore Structure of Corncob-Derived Hard Carbons by Pyrolysis to Improve Sodium Storage

by Ning-Jing Song, Nannan Guo, Canliang Ma, Yun Zhao, Wanxi Li and Boqiong Li

Molecules 2023, 28(8), 3595; https://doi.org/10.3390/molecules28083595 - 20 Apr 2023

Cited by 5 | Viewed by 1606

Abstract

Biomass-derived hard carbon materials are considered as the most promising anode materials for sodium-ion batteries (SIBs) due to their abundant sources, environmental friendliness, and excellent electrochemical performance. Although much research exists on the effect of pyrolysis temperature on the microstructure of hard carbon [...] Read more.

Biomass-derived hard carbon materials are considered as the most promising anode materials for sodium-ion batteries (SIBs) due to their abundant sources, environmental friendliness, and excellent electrochemical performance. Although much research exists on the effect of pyrolysis temperature on the microstructure of hard carbon materials, there are few reports that focus on the development of pore structure during the pyrolysis process. In this study, corncob is used as the raw material to synthesize hard carbon at a pyrolysis temperature of 1000~1600 °C, and their interrelationationship between pyrolysis temperature, microstructure and sodium storage properties are systematically studied. With the pyrolysis temperature increasing from 1000 °C to 1400 °C, the number of graphite microcrystal layers increases, the long-range order degree rises, and the pore structure shows a larger size and wide distribution. The specific capacity, the initial coulomb efficiency, and the rate performance of hard carbon materials improve simultaneously. However, as the pyrolysis temperature rises further to 1600 °C, the graphite-like layer begins to curl, and the number of graphite microcrystal layers reduces. In return, the electrochemical performance of the hard carbon material decreases. This model of pyrolysis temperatures–microstructure–sodium storage properties will provide a theoretical basis for the research and application of biomass hard carbon materials in SIBs. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion)

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13 pages, 3023 KiB

Open AccessArticle

Study on the Controllable Preparation of Nd³⁺ Doped in Fe₃O₄ Nanoparticles for Magnetic Protective Fabrics

by Xiaolei Song, Congzhu Xu, Wendong Yao, Jieyun Wen, Qufu Wei, Yonggui Li and Xinqun Feng

Molecules 2023, 28(7), 3175; https://doi.org/10.3390/molecules28073175 - 03 Apr 2023

Viewed by 1314

Abstract

Magnetic protective fabrics with fine wearability and great protective properties are highly desirable for aerospace, national defense, and wearable protective applications. The study of the controllable preparation method of Nd³⁺ doped in Fe₃O₄ nanoparticles with supposed magnetic properties remains [...] Read more.

Magnetic protective fabrics with fine wearability and great protective properties are highly desirable for aerospace, national defense, and wearable protective applications. The study of the controllable preparation method of Nd³⁺ doped in Fe₃O₄ nanoparticles with supposed magnetic properties remains a challenge. The characterization of the microstructure, elemental composition, and magnetic properties of NdFe₂O₄ nanoparticles was verified. Then, the surface of NdFe₂O₄ was treated with glyceric acid to provide sufficient –OH. Subsequently, the connection of the nanoparticle by the succinimide group was studied and then grafted onto cotton fabrics as its bridging effect. The optimal loading rate of the functional fabrics with nanoparticles of an average size of 230 nm was 1.37% after a 25% alkali pretreatment. The color fatness to rubbing results showed better stability after washing and drying. The corresponding hysteresis loop indicated that the functional fabrics exhibited typical magnetism behavior with a closed “S” shape and a magnetic saturation value of 17.61 emu.g⁻¹ with a particle size of 230 nm. However, the magnetic saturation value of the cotton fabric of 90 nm was just 4.89 emu.g⁻¹, exhibiting controllable preparation for the aimed electromagnetic properties and great potential in radiation protective fields. The electrochemical properties of the functional fabrics exhibited extremely weak electrical conductivity caused by the movement of the magnetic dipole derived from the NdFe₂O₄ nanoparticles. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion)

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15 pages, 2924 KiB

Open AccessArticle

CoO–Co Heterojunction Covered with Carbon Enables Highly Efficient Integration of Hydrogen Evolution and 5-Hydroxymethylfurfural Oxidation

by Lei Zhao, Shichao Du, Rui Gong, Wanqi Jia, Zhimin Chen and Zhiyu Ren

Molecules 2023, 28(7), 3040; https://doi.org/10.3390/molecules28073040 - 29 Mar 2023

Cited by 1 | Viewed by 1429

Abstract

The renewable-energy-driven integration of hydrogen production and biomass conversion into value-added products is desirable for the current global energy transition, but still a challenge. Herein, carbon-coated CoO–Co heterojunction arrays were built on copper foam (CoO–Co@C/CF) by the carbothermal reduction to catalyze the hydrogen [...] Read more.

The renewable-energy-driven integration of hydrogen production and biomass conversion into value-added products is desirable for the current global energy transition, but still a challenge. Herein, carbon-coated CoO–Co heterojunction arrays were built on copper foam (CoO–Co@C/CF) by the carbothermal reduction to catalyze the hydrogen evolution reaction (HER) coupled with a 5-hydroxymethylfurfural electrooxidation reaction (HMFEOR). The electronic modulation induced by the CoO–Co heterojunction endows CoO–Co@C/CF with a powerful catalytic ability. CoO–Co@C/CF is energetic for HER, yielding an overpotential of 69 mV at 10 mA·cm⁻¹ and Tafel slope of 58 mV·dec⁻¹. Meanwhile, CoO–Co@C/CF delivers an excellent electrochemical activity for the selective conversion from HMF into 2,5-furandicarboxylic acid (FDCA), achieving a conversion of 100%, FDCA yield of 99.4% and faradaic efficiency of 99.4% at the lower oxidation potential, along with an excellent cycling stability. The integrated CoO–Co@C/CF||CoO–Co@C/CF configuration actualizes the H₂O–HMF-coupled electrolysis at a satisfactory cell voltage of 1.448 V at 10 mA·cm⁻². This work highlights the feasibility of engineering double active sites for the coupled electrolytic system. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion)

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10 pages, 8646 KiB

Open AccessCommunication

Improving the Reaction Kinetics by Annealing MoS₂/PVP Nanoflowers for Sodium-Ion Storage

by Yuan Li, Lingxing Zan and Jingbo Chen

Molecules 2023, 28(7), 2948; https://doi.org/10.3390/molecules28072948 - 25 Mar 2023

Cited by 2 | Viewed by 1318

Abstract

Under the ever-growing demand for electrochemical energy storage devices, developing anode materials with low cost and high performance is crucial. This study established a multiscale design of MoS₂/carbon composites with a hollow nanoflower structure (MoS₂/C NFs) for use in [...] Read more.

Under the ever-growing demand for electrochemical energy storage devices, developing anode materials with low cost and high performance is crucial. This study established a multiscale design of MoS₂/carbon composites with a hollow nanoflower structure (MoS₂/C NFs) for use in sodium-ion batteries as anode materials. The NF structure consists of several MoS₂ nanosheets embedded with carbon layers, considerably increasing the interlayer distance. Compared with pristine MoS₂ crystals, the carbon matrix and hollow-hierarchical structure of MoS₂/C exhibit higher electronic conductivity and optimized thermodynamic/kinetic potential for the migration of sodium ions. Hence, the synthesized MoS₂/C NFs exhibited an excellent capacity of 1300 mA h g⁻¹ after 50 cycles at a current density of 0.1 A g⁻¹ and 630 mA h g⁻¹ at 2 A g⁻¹ and high-capacity retention at large charge/discharge current density (80% after 600 cycles 2 A g⁻¹). The suggested approach can be adopted to optimize layered materials by embedding layered carbon matrixes. Such optimized materials can be used as electrodes in sodium-ion batteries, among other electrochemical applications. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion)

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13 pages, 2985 KiB

Open AccessArticle

Rational Fabrication of Defect-Rich and Hierarchically Porous Fe-N-C Nanosheets as Highly Efficient Oxygen Reduction Electrocatalysts for Zinc-Air Battery

by Sensen Li, Yan Lv, Sawida Elam, Xiuli Zhang, Zhuojun Yang, Xueyan Wu and Jixi Guo

Molecules 2023, 28(7), 2879; https://doi.org/10.3390/molecules28072879 - 23 Mar 2023

Cited by 2 | Viewed by 1202

Abstract

The rational design of morphology and structure for oxygen reduction reaction (ORR) catalysts still remains a critical challenge. Herein, we successfully construct defect-rich and hierarchically porous Fe-N-C nanosheets (Fe-N-CNSs), by taking advantage of metal-organic complexation and a mesoporous template. Benefiting from the advantages [...] Read more.

The rational design of morphology and structure for oxygen reduction reaction (ORR) catalysts still remains a critical challenge. Herein, we successfully construct defect-rich and hierarchically porous Fe-N-C nanosheets (Fe-N-CNSs), by taking advantage of metal-organic complexation and a mesoporous template. Benefiting from the advantages of high density of active sites, fast mass transfer channels, and sufficient reaction area, the optimal Fe-N-CNSs demonstrate satisfactory ORR activity with an excellent half-wave potential of up to 0.87 V, desirable durability, and robust methanol tolerance. Noteworthy, the Fe-N-CNSs based zinc–air battery shows significant performance with a peak power density of 128.20 mW cm⁻² and open circuit voltage of 1.53 V, which reveals that the Fe-N-CNSs catalysts present promising practical application prospects. Therefore, we believe that this research will provide guidance for the optimization of Fe-N-C materials. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion)

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Review

Jump to: Research

20 pages, 5955 KiB

Open AccessReview

Design and Synthesis Strategy of MXenes-Based Anode Materials for Sodium-Ion Batteries and Progress of First-Principles Research

by Dan Su, Hao Zhang, Jiawei Zhang and Yingna Zhao

Molecules 2023, 28(17), 6292; https://doi.org/10.3390/molecules28176292 - 28 Aug 2023

Viewed by 1394

Abstract

MXenes-based materials are considered to be one of the most promising electrode materials in the field of sodium-ion batteries due to their excellent flexibility, high conductivity and tuneable surface functional groups. However, MXenes often have severe self-agglomeration, low capacity and unsatisfactory durability, which [...] Read more.

MXenes-based materials are considered to be one of the most promising electrode materials in the field of sodium-ion batteries due to their excellent flexibility, high conductivity and tuneable surface functional groups. However, MXenes often have severe self-agglomeration, low capacity and unsatisfactory durability, which affects their practical value. The design and synthesis of advanced heterostructures with advanced chemical structures and excellent electrochemical performance for sodium-ion batteries have been widely studied and developed in the field of energy storage devices. In this review, the design and synthesis strategies of MXenes-based sodium-ion battery anode materials and the influence of various synthesis strategies on the structure and properties of MXenes-based materials are comprehensively summarized. Then, the first-principles research progress of MXenes-based sodium-ion battery anode materials is summarized, and the relationship between the storage mechanism and structure of sodium-ion batteries and the electrochemical performance is revealed. Finally, the key challenges and future research directions of the current design and synthesis strategies and first principles of these MXenes-based sodium-ion battery anode materials are introduced. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion)

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