Journal of Environmental Chemical Engineering
·
2024
·
IF 7.4
Qingwen Fan,Chaoyun Song,Peng Fu
In this study, we explored the effectiveness of enhancing microwave absorption capabilities of biomass-derived porous carbon by introducing MnO 2 through thermochemical techniques. The results showed that the MnO 2 -C exhibited higher values in both the real and imaginary parts of the dielectric constant compared to the Control, indicating that the addition of MnO 2 significantly enhanced the energy storage and dissipation capabilities. Although the magnetic loss properties of the composite were relatively weak, the increase in conductive and dielectric losses compensated for this aspect. Moreover, the loading of MnO 2 optimized the dielectric losses and promoted the reconstruction of charge, enabling MnO 2 -C to demonstrate superior microwave absorption performance, particularly in the high-frequency range. This is attributed to the multiple polarization mechanisms present in MnO 2 -C, including interfacial and dipolar polarization, which play a crucial role in enhancing dielectric losses. Additionally, a multilevel porous structure significantly enhanced the scattering and reflection of microwaves, further improving the absorption effectiveness. Consequently, these characteristics contribute to the MnO 2 -C achieving a minimum reflection loss value of −46.2 dB and an expanded effective absorption bandwidth. Overall, the MnO 2 -C composite, with its optimized electromagnetic properties and complex microstructure, provides valuable insights for the development of new, highly efficient microwave absorption materials.
研究领域:
材料科学
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电磁学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Yingying Fang,Wenbo Zhou,Yihuan Cheng,Yuge Zhang,Tingting Yu,Shaoxian Song
The high-value utilization of steel pickling waste liquid (SPWL) is an important direction in the resourceful utilization of hazardous waste. In this study, nano-Fe 3 O 4 prepared from SPWL (S-Fe 3 O 4 ) was hydrothermally compounded with MnO 2 as Fe 3 O 4 -MnO 2 (SFM), which were compared with Fe 3 O 4 -MnO 2 (CFM) prepared by chemical reagents. The synthetic materials were evaluated by SEM, VSM, BET, XRD, and zeta potential, the results show that the spherical S-Fe 3 O 4 was encapsulated by spiny spherical shell-like MnO 2 , and the SFM has a high saturation magnetization and specific surface area (159.91 m 2 /g). The adsorption experiments demonstrated that the adsorption effect of SFM on Pb 2+ is highly similar to that of CFM. The maximal adsorption capacity of SFM reached 129.74 mg/g under ideal composite ratio and pH conditions, and the adsorption process was unaffected by competing heavy metal ions coexisting in the environment. Moreover, the high saturation magnetization strength of the SFM makes it simple to separate materials under a magnetic field. The pseudo-second-order kinetics and Langmuir isotherm models provided a good description of the Pb 2+ adsorption on SFM. XPS and FTIR analysis provided evidence that the adsorbent surface has a high concentration of -OH functional groups, and that O atoms serve as Pb 2+ binding sites, suggesting that ion exchange occurs during the SFM adsorption process. In this paper, we developed a cheap SFM with high adsorption performance and provided a novel approach to the high-value application of SPWL.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF NANOPARTICLE RESEARCH
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2021
·Vol. 23
·期 2
·1-11
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IF 2.253
He Yunbing,Pan Xuexue,Kuang Liping,Hu Bo,Zha Qinbing,Chen Xinman
The MnCo 2 O 4.5 @MnO 2 composite nanomaterial was successfully designed and synthesized via successive hydrothermal and subsequent calcination methods, in which MnO 2 nanosheets coated on MnCo 2 O 4.5 nanoneedle arrays were directly grown on Ni foam. Compared with pristine MnCo 2 O 4.5 nanoneedle electrode, MnCo 2 O 4.5 @MnO 2 composite electrode exhibits a high specific discharge capacitance of 1155 F g -1 at a current density of 1.43 A g -1 , the capacitance retention of 93.4% after 5000 cycles, and low initial internal resistance of 1.9 Ω. The results reveal that the rational design of MnCo 2 O 4.5 @MnO 2 electrode with such structure and composition is an effective strategy to improve electrochemical performances of MnCo 2 O 4.5 . Due to unique nanostructure and brilliant electrochemical properties of MnCo 2 O 4.5 @MnO 2 electrode, the fabricated hybrid supercapacitor based on MnCo 2 O 4.5 @MnO 2 positive electrode and activated carbon negative electrode delivers the wide operating voltage window of 1.6 V, a capacitance retention of 87.8% after 8000 continuous charge-discharge cycles at a current density of 1.33 A g -1 , the maximum energy density of 40.8 Wh kg -1 at a power density of 263.9 W kg -1 , and highest power density of 1336.6 W kg -1 to achieve an energy density of 24.4 Wh kg -1 . Herein, the designed MnCo 2 O 4.5 @MnO 2 composite is a distinguished candidate material for hybrid supercapacitor.
研究领域:
材料科学
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能源存储与转换
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2022
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IF 7.392
Tong Ding,Wenxiao Zhao,Yuqing Sun,Shilong Li,Tianxiang Yu,Wenheng Jing
In this work, a novel 2D Fe 3 O 4 -MnO 2 hollow fiber ceramic membrane (HFCM) with both excellent separation performance and high catalytic activity was constructed. The Fe 3 O 4 nanoparticles were deposited on 2D MnO 2 nanoplates to increase the Mn 3+ content, and then the nanoplates were pressure-driven and sintered on the surface of the hollow fiber ceramic supports to obtain 2D Fe 3 O 4 -MnO 2 -HFCMs. Electron spin resonance analysis confirmed that hydroxyl radicals and superoxide radicals played a major role in oxidative degradation and tetracycline hydrochloride (TCH) removal was 86.9 %. Noteworthily, TCH was concentrated on the membrane interface due to the concentration polarization effect, which increases the probability of binding free radicals from the catalytic membrane layer, thus enhancing the catalytic performance and the anti-fouling capability of the membrane. The 2D Fe 3 O 4 -MnO 2 -HFCM can be applied in wastewater treatment due to its superior catalytic ozonation activity and high separation performance.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2024
·
IF 4.1
Mengjie Pan,Huachen Lin,Lin Sun,Yulong Ying,Hong Jia,Yu Liu
Research into electrode materials that are low-cost, possess high capacity, and exhibit long cycle life is pivotal for the advancement of supercapacitor technology. Herein, a CoP/P-C/MnO 2 @CC composite is synthesized by solution impregnation and high temperature phosphating. The unique combination of nanotubes and MnO 2 nanosheets reduces ion and electron transmission distance and significantly increases active sites. The CoP/P-C/MnO 2 @CC electrode demonstrates a specific capacitance of 742.0 F g −1 at 1 A g −1 , a substantial improvement over the counterpart prior to KMnO 4 immersion (459.4 F g −1 ). Furthermore, an asymmetric supercapacitor based on the CoP/P-C/MnO 2 @CC electrode was assembled, achieving a high energy density of 93.12 Wh kg −1 at a power density of 800 W kg −1 . Meanwhile, the device maintains 77.3 % of its original capacity after 8000 cycles, demonstrating good cycle stability. This study not only presents an attractive electrode material with unique structure, but also provides a referential methodology for developing superior electrodes.
研究领域:
材料科学
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能源存储技术
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS & DESIGN
·
2021
·
IF 7.991
Lu Gan,Xingyu Fang,Lijie Xu,Linjie Wang,Ying Wu,Boren Dai,Wen He,Jiangtao Shi
In this study, kenaf carbon fiber (KCF) was prepared via direct pyrolysis of kenaf fiber. Afterwards, the prepared KCF was incorporated with δ-MnO 2 to prepare a series of δ-MnO 2 /KCF composites. The as-prepared composites were then used to degrade bisphenol A (BPA) in water via oxidative catalysis. Significantly enhanced oxidative capability of the δ-MnO 2 /KCF was realized, since the KCF could not only prevent δ-MnO 2 aggregation, but also facilitate electron transferring between δ-MnO 2 and BPA. The impacts of catalyst dosage, initial pollutant concentration, solution pH value, temperature, Mn 2+ and natural organic matters on the performance of the δ-MnO 2 /KCF composites were examined in detail. The results showed that 0.025 mM of BPA could be completely degraded within 10 min by 0.5 g/L of the catalyst at the pH value of 3.80. The subsequent LC-MS analysis results indicated that the δ-MnO 2 /KCF initiated BPA oxidative degradation and mineralization through capturing one electron from the BPA molecules and forming BPA radicals. Moreover, the as-prepared δ-MnO 2 /KCF composites also had promising long-time use stability and reusability. This study demonstrates a potentially applicable and sustainable biochar support which could enrich the performance of a catalyst for refractory organic contaminant removals in aqueous environment.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
·
IF 6.2
Junjie Qian,Tao Wang,Qingliang Shan,Shaohua Wang,Xiaozhen Zhang,Xuebing Hu,Qibing Chang,Yongqing Wang
Silicon carbide (SiC) is expected to be the new-generation electromagnetic wave (EMW) absorber. In this context, the SiC/C composites were first prepared through a hydrothermal method using glucose as the carbon source. Then SiC/MnO 2 composites were fabricated by a second hydrothermal reaction using potassium permanganate (KMnO 4 ) as raw material. With glucose content increased to 10 wt%, the composition exhibited outstanding EMW absorption performance with the minimum reflection loss value of − 55.7 dB at the frequency of 2.1 GHz, and effective absorption bandwidth can cover the entire S-band by adjusting sample thickness. Therefore, the SiC/MnO 2 composites present a promising EMW-absorbing material for low-frequency applications.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Ze Yang,Yuanyu Chen,Qianghui Tian,Haixia Zhang,Ying Hou,Junjie Guo
The design and synthesis of hollow porous heterostructures from multiple components is expected to impart excellent properties to the electrochemically active materials owing to their high internal voids, high surface area, and high pore volume , which are beneficial for electrolyte infiltration. However, the development of optimized electrode materials for hollow porous heterostructure storage fell behind expectations. To address these challenges, we prepared a CuCo 2 S 4 @MnO 2 composite on a foam nickel substrate to create a hollow porous heterostructure. The optimized composite possesses high areal capacitance of 14.9 F cm −2 (or a specific capacitance of 1643 F g −1 ) at 3 mA cm −2 , and 83.4% capacitance retention after 30,000 cycles in a three-electrode configuration. The NF@CuCo 2 S 4 @MnO 2 //AC asymmetric supercapacitor can achieve high energy density (1.2 mWh cm −2 ) and power density (2.4 mW cm −2 ) due to the wide cell voltage in aqueous electrolyte and high particular capacitances from both CuCo 2 S 4 and MnO 2 improved by the hollow porous heterostructure. Furthermore, the NF@CuCo 2 S 4 @MnO 2 //AC ASC can light up an LED display screen. Overall, this work demonstrates the great potential and broad prospects for application in energy storage of hollow porous heterostructures.
研究领域:
材料科学
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电化学能源存储
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Xiao Li,Yuan-Zhuo Tan,An-Ran Xue,Zhuo Wang,Yuan-Ru Guo,Qing-Jiang Pan
In research out of the sustainable electrochemical energy storage material , NiCo-LDH/MnO 2 composite has been prepared via simple hydrothermal method . The experimental characterizations of XRD , SEM/TEM and XPS have been utilized to explore the structure and morphology of prepared composite. The needle-like MnO 2 was found adhered to NiCo-LDH sheet. The composite's electrochemical properties were evaluated through cyclic voltammetry , galvanostatic charge-discharge and electrochemical impedance spectroscopy . It has been realized that the MnO 2 dosage not only changes the composite's microstructure but also affects its electrochemical properties. The best specific capacitance (2602 F g −1 at a current density of 1 A g −1 ) was achieved for the composite sample with 38% MnO 2 (mass), which is almost two times high from the same composite in previous reports. With the sample, the assembled asymmetric supercapacitor exhibits a remarkable energy density of 19.56 Wh . Kg −1 at 800.29 W Kg −1 . It could be attributed to the synergetic effects of two components as well as their good interfacial coupling. The good electrochemical activity makes our synthesized composite feasible to be applied as electrode material and provides valuable insights for the development of smart capacitors utilizing NiCo-LDH.
研究领域:
材料科学
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电化学
·
能源存储
✓ 已验证
产品关联
DOI
高影响因子
Nanoscale
·
2025
·
IF 5.1
Huangying Guo,Wenyu Wan,Pengcheng Deng,Yang Luo,Xing Zhou
Cross and secondary electromagnetic pollution is a major challenge in current electromagnetic interference (EMI) mitigation. In this study, Fe3O4@MnO2 composite microspheres and AgNWs were prepared using modified solvothermal and hydrothermal methods. By optimizing the fabrication process and structural design of electromagnetic shielding composite films, we successfully constructed a composite film with superior shielding performance and reduced thickness. The Fe3O4@MnO2 composite exhibited an SEA/SET ratio of 83.32%, along with a high absorption coefficient A, indicating its dominant role in electromagnetic wave absorption, thereby mitigating excessive reflection. Results demonstrated that the gradient network-structured film possessed significantly enhanced electromagnetic wave absorption and attenuation capabilities compared to other three composite materials. The SEA/SET of the gradient network-structured film reached 86%, with a maximum SET of 58.65 dB. This hierarchical structure not only improves shielding effectiveness at reduced thickness but also enhances absorption, achieving the ultimate goal of high absorption with low reflection while minimizing resource consumption.
研究领域:
材料科学
·
电磁学
·
纳米技术
·
复合材料
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ELECTROCHIMICA ACTA
·
2017
·
IF 4.798
Yuhong Bi,Amit Nautiyal,Huaiping Zhang,Jujie Luo,Xinyu Zhang
A facile and energy efficient microwave synthesis of NiO/MnO 2 composite is presented in this study. The NiO nanoparticles (∼30 nm) and composite of NiO nanoparticles with nano-particle MnO 2 were grown on the surface of graphite. The morphologies and electrochemical performance of NiO@graphite and NiO/MnO 2 @graphite composite were tested and compared. The SEM results showed that addition of MnO 2 prevented the agglomeration of NiO nanoparticles. The electrochemical results of NiO/MnO 2 @graphite has demonstrated better performance than NiO@graphite, with higher specific capacitance of 102.78 mAh g −1 at 1 A g −1 and superior cycling stability with specific capacitance retention of 140% over more than 1500 cycles. The excellent electrochemical performance of NiO/MnO 2 @graphite makes it suitable for electrode material of supercapacitors .
研究领域:
材料科学
·
电化学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
Batteries & Supercaps
·
2025
·
IF 4.7
Xu Zhang,Heng Xiang,Chuang Pang,Keyu Zhao,Zhongli Zou,Kui Cheng
The development of flexible energy-storage devices is limited by the poor conductivity, limited cycling stability, and slow electron/ion transport of metal oxides. Optimizing their structure and performance is crucial for advancing these technologies. Herein, a hollow cubic core–shell Co 3 O 4 @MnO 2 is synthesized via annealing and hydrothermal approaches. This composite enjoys advantages of the high electrical conductivity of Co 3 O 4 and the excellent pseudocapacitive properties of MnO 2 ; in addition, the hollow structure of the composite effectively mitigates the mechanical stress caused by volume changes during charge–discharge cycles. Owing to its large specific surface area and stable framework, Co 3 O 4 @MnO 2 achieves a high specific capacitance of 670.2 F g −1 and retains 83.18% of its initial capacitance after 10,000 cycles, demonstrating exceptional electrochemical stability and durability. Subsequently, an all-solid-state flexible supercapacitor was assembled using Co 3 O 4 @MnO 2 positive electrode and a negative electrode made of reduced graphene oxide hydrogel. The device achieves a high energy density of 78.2 W h kg −1 and a power density of 11,500 W kg −1 . Further, even after 10,000 charge–discharge cycles, it retained 73.1% of its initial capacitance, demonstrating potential for flexible energy-storage applications. This article highlights the advantages of Co 3 O 4 @MnO 2 in enhancing supercapacitor performance and offers insights for cost-effective cobalt-based energy-storage systems. Graphical The diagram illustrates the synthesis process of Co 3 O 4 @MnO 2 composites, in which a hollow core–shell structure is successfully constructed with Co 3 O 4 cages serving as the core and MnO 2 nanosheets as the shell.
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）