Materials Research Express
·
2018
·Vol. 5
·期 5
·056305
·
IF 1.151
Xiaogang Su,Jun Wang,Bin Zhang,Wei Chen,Qilei Wu,Wei Dai,Yi Zou
Recently, owing to the radiation and interference from electromagnetic wave (EMW), the requirements of EMW absorbing materials have been increasing. Herein, a novel absorber composed of graphite nanosheets@Fe3O4 composites decorated comb-like MnO2 (GNFM) has been successfully synthesized via a facile two steps, characterized using x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, vibrating sample magnetometry (VSM) and vector network analyzer (VNA). The ternary composites with enhanced microwave absorption performance are due to the complementary effects of electroconductive material (graphite nanosheets), dielectric materials (MnO2) and magnetic material (Fe3O4 nanospheres). Hence, the maximum reflection loss of GNFM/epoxy composites is up to −31.7 dB at 5.85 GHz with absorbing thickness of 4.5 mm, and the efficient frequency bandwidth below −10 dB can reach up to 4.47 GHz (11.87–16.34 GHz) at matching thickness of 2 mm. The results demonstrate that GNFM could be regarded as a novel type of microwave absorbing material.
研究领域:
材料科学
·
电磁学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Lili Cao,Yuxiang Chen,Shane Feng,Yanli Su
To reduce the dielectric loss of MXene/PVDF composites near the percolation threshold, a MnO 2 /MXene hybrid structure was successfully synthesized via an ultrasonic-assisted solution process, and MnO 2 /MXene/PVDF composite films were prepared by a solution casting method. The effects of different amounts of MnO 2 nanorods on the microstructure, thermal stability, dielectric properties and mechanical properties of the composite films were investigated. At 1 kHz, the dielectric constant of 7 wt% MnO 2 /MXene/PVDF is 37.3, and the dielectric loss is as low as 0.05. The electric modulus curve, Nyquist curve and equivalent analog circuit of the composites revealed strong interface polarization and microcapacitance effects in the composites. In addition, the composite films exhibit excellent mechanical properties, and the storage modulus of the composite film loaded with 10 wt% MnO 2 is 1990.5 MPa, which is 3.44 times that of pure PVDF. This study confirms that incorporating MnO 2 nanorods into MXene/PVDF composites is an effective approach for fabricating high-performance dielectric composites.
研究领域:
材料科学
·
电介质材料
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Jiangtao Liu,Shaohui Zhang,Baosheng Liu,Xuning Feng,Zhenbo Wang
A supercapacitor electrode material was synthesized by using hollow carbon spheres prepared via high temperature sintering of dopamine hydrochloride and subsequent coating with MnO 2 . SEM, TEM and analysis of energy pattern were used to characterize the structure, morphology and elemental composition of the material, which proved that the material had a good hollow structure and uniform surface morphology , and that MnO 2 was successfully coated on the surface of the carbon material. Electrochemical characterization using charge-discharge cycles at constant current and other methods show that the prepared materials have good specific capacitance and cycle stability, and have a specific capacitance of 198 F.g −1 at a current of 1 A·g −1 . When the charge and discharge cycle is carried out at 10 A·g −1 for 5000 cycles, the capacitance remains stable at more than 180 F·g −1 .
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
Journal of Energy Storage
·
2023
·
IF 9.4
Cunhao Han,Yuchao Zhu,Huanzhi Zhang,Cong Feng,Shendao Zhang,Fen Xu,Lixian Sun,Xiangcheng Lin,Lei Ma,Hongliang Peng,Yazhen Wang,Yongpeng Xia,Bin Li,Erhu Yan,Pengru Huang
Solar energy is considered as a renewable energy source , but it still exists imbalance between energy supply and energy consumption. Although phase change materials (PCMs) can supply an effective way to improve solar energy utilization efficiency with the help of their excellent energy storage capacity , their poor solar-thermal conversion performance significantly reduces energy storage capacity and seriously restricts their applications in solar energy utilization fields. Herein, this work innovatively prepared MnO 2 -decorated double-shell microencapsulated PCMs using electrochemical adsorption and redox methods to cover a second compact shell of MnO 2 on the first polymeric shell, which integrate the advantages of organic and inorganic shell materials with multi-functions and broaden the wide-spread applications of PCMs. The MnO 2 -decorated double-shell endows the microencapsulated PCMs with multi-functions and broadens their wide-spread applications. The excellent electrochemical and optical performances of MnO 2 shell provide the microencapsulated PCMs with a high light-to-heat conversion efficiency of 93 %, and also endow the composite PCMs with a specific capacitance of 364 F/g. Meanwhile, phase change enthalpy of the microencapsulated PCMs is in the range of 133.56–152.71 J/g. These results confirm that the MnO 2 -decorated double-shell microencapsulated PCMs have a considerable potential in solar energy utilization and electrochemical fields.
研究领域:
材料科学
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
·
IF 6.2
Jiangmin Song,Guanxing Huang,Dongya Han,Qinxuan Hou,Ruinan Liu
High performance and high permeability of reactive materials are crucial issues for the remedy of arsenic (As)-enriched groundwater by permeable reactive barriers. The remediation strategy integrating adsorption and oxidation has gained wide concerns due to its deep removal for As(Ⅲ). In this study, a granular bifunctional nanocomposite MgO-Chitosan-MnO 2 (MgO-CS-MnO 2 ) was fabricated as permeable reactive media for the in-situ remediation for high As groundwater. The needle structure of MnO 2 could provide adequate oxidation sites, furthermore, the multilayer porous characteristic of MgO-CS could also meet higher adsorption capacity. As a result, the estimated maximal adsorption capacity of MgO-CS-MnO 2 for As(Ⅲ) reached to 266.61 mg/g and 578.05 mg/g for arsenate (As(Ⅴ)), which are much higher than current similar adsorbents. The adsorption behaviors of As(Ⅲ/Ⅴ) follow pseudo-second-order kinetic model and Freundlich isotherm model, suggesting that both As(Ⅲ) and As(Ⅴ) are mainly chemisorbed onto MgO-CS-MnO 2 . It could perform effectively in a broad range of pH values (3−11), moreover, competing oxyanions (CO 3 2- , NO - , and SO 4 2- ), organic matters (humic acid) and ion strength exert no significant influence towards As remediation. XPS results revealed As(Ⅲ) adsorbed onto composite completely transformed to As(Ⅴ), and removal mechanisms involved oxidation and metal-O-As(Ⅲ/Ⅴ) complexation. In addition, it can be easily regenerated and recycled maintaining an excellent adsorption and oxidative ability. Besides, Column experiment demonstrated this composite column could effectively treat 1300 and 1700 bed volume (BV) of synthetic As(Ⅲ/Ⅴ)-contaminated groundwater, respectively. Therefore, MgO-CS-MnO 2 have a great potential applicability towards high As groundwater improvement as permeable reactive media.
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
CATALYSIS TODAY
·
2018
·
IF 4.667
Ruimei Fang,Qiuyu Feng,Haibao Huang,Jian Ji,Miao He,Yujie Zhan,Biyuan Liu,Dennis Y.C. Leung
δ -MnO 2 was prepared via a facile in-situ redox reaction and used for catalytic oxidation of HCHO, a major indoor air pollutant. The washing treatment during catalyst preparation could impose great effect on content of K + and catalytic activity. δ -MnO 2 catalyst without washing treatment contains the highest content of K + ion and exhibits the best catalytic activity among various δ -MnO 2 samples. The HCHO removal efficiency keeps at 100% for first 600 min. The δ -MnO 2 samples were characterized by advanced technologies including XRD, Raman, XPS, TPR, TPD and in-situ DRIFTS. The XPS results indicates that K + ions increases the AOS value of Mn and the ratio of surface-adsorbed oxygen over δ -MnO 2 . The content of K + ions improves the amount and redox ability of surface mobile oxygen species, enhancing catalytic oxidation of HCHO.
研究领域:
环境科学
·
催化材料
✓ 已验证
DOI
高影响因子
Journal of Water Process Engineering
·
2024
·
IF 6.3
Zhuoyue Liu,Dong Cheng,Haochen Yin,Jianghao Zhao,Jiale Zhang,Rongzhi Chen,Shengjiong Yang,Jing Wei,Gen Wang
Nascent MnO 2 colloids produced during the permanganate oxidation process is highly oxidative and appealing for eliminating emerging organic contaminants (EOCs). However, the nascent MnO 2 colloids usually shows dense bulked structure, which blocks the availability of active sites and further enhancement of the reactivity. Herein, spherical nascent MnO 2 colloids with mesoporous structure were synthesized via redox reactions between colloidal nanospheres of plant polyphenol (e.g., tannic acid) and permanganate. The mesoporous nascent MnO 2 colloids shows highly exposure of active sites with abundant bulk-Mn(III) on the surface (16.2 mol%), and thus exhibits outstanding oxidation performance toward the oxidation of phenolic contaminants. Complete removal of bis-phenol A (BPA, 10 mg/L) was obtained with 1.0 mM of mesoporous nascent MnO 2 colloids in 40 min at neutral pH. Mechanism study reveals that both Mn(III) and Mn(IV) contribute to the oxidation of BPA. The presence of bulk-Mn(III) on the surface greatly promotes the reactivity of the mesoporous nascent MnO 2 colloids, leading to a high kinetic of 0.12 min −1 during the initial 10 min. The nascent mesoporous MnO 2 colloids exhibits high selectivity toward electron rich phenolic contaminants and good performance in complicated water matrix, revealing a promising potential for further application. This work provides a distinct case for engineering novel structured nascent MnO 2 colloids for efficient elimination of EOCs in water.
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
CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Jianwen Ge,Li Liu,Yu Cui,Rui Li,Fandi Meng,Fuhui Wang
Whereas growing numbers of strong-absorption materials have been synthesized in recent years, it is also necessary to design broad-bandwidth, low-thickness, high-intensity absorbers. The ternary Fe 3 O 4 @SiO 2 @MnO 2 hybrids were fabricated via hydrothermal and hydrolysis processes, combined with typical core-shell structure characteristics and heterogeneous properties, further generating interfacial polarization behavior and enhancing anisotropy. Investigations of micromorphology manifested the hierarchical characteristic via the presence of inner mesoporous Fe 3 O 4 cores, outer SiO 2 layers (approximately 10 nm) and MnO 2 nanosheets as the surface of the hybrids. On the basis of rational design, the optimized multi-layers absorber exhibited excellent absorption performance with optimal reflection loss (RL min ) of −50.2 dB at 13.9 GHz, and the effective absorption band (EAB) is up to 5.1 GHz from 11.5 GHz to 16.6 GHz with the thickness of 2.6 mm. Due to the large surfaces, high porosity as well as the synergistic effect derived from the magnetic Fe 3 O 4 cores and dielectric SiO 2 @MnO 2 layers, this effective strategy may be endowed with high potential to design high-efficient absorbers.
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
·
电化学能源存储
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2022
·
IF 5.518
Shuaishuai Zhang,Lingling Zhang,Li Liu,Xiao Wang,Jing Pan,Xiqiang Pan,Han Yu,Shuyan Song
Formaldehyde (HCHO) is a harmful gas of volatile organic compounds (VOCs) and its removal is essential to protect human health. Low-temperature elimination of HCHO by non-noble catalysts is one of the most crucial research topics nowadays. Herein, ultrathin MnO 2 nanosheets grown on Ni-Co layered double hydroxide nanocages (NiCo-LDH@MnO 2 ) were fabricated via a hydrothermal method and subsequently used to eliminate HCHO at low temperature. The NiCo-LDH@MnO 2 -1 catalysts (mass ratio of NiCo-LDH to KMnO 4 of 1:1) performed excellent catalytic activity towards HCHO (100 ppm) at 80 °C. After the fifth cycles, the NiCo-LDH@MnO 2 -1 exhibited excellent stable activity towards the oxidation of HCHO. According to the physicochemical characterization analysis, the enhanced catalytic activity over NiCo-LDH@MnO 2 is attributed to the unique hollow nanocage structure, suitable composition , as well as the synergistic influence of MnO 2 and NiCo-LDH. The results of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) presented that the abundant active species (e.g., O 2 − , O − and –OH) can contribute to the adsorption of HCHO on the surface of NiCo-LDH@MnO 2 and promote to oxidize HCHO into the DOM, formate, and carbonate species. Furthermore, NiCo-LDH@MnO 2 displayed good durability for low concentration HCHO (∼9 ppm) at room temperature under 12 h, indicating that the NiCo-LDH@MnO 2 is competitive and inexpensive efficient catalysts for the applications of indoor HCHO purification.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2018
·Vol. 42
·期 9
·6770-6777
·
IF 3.201
Kai Luo,Shi-Xi Zhao,Yi-Feng Wang,Shu-Jin Zhao,Xi-Hui Zhang
Petal-like δ-MnO2 microspheres were successfully synthesized by a very simple hydrothermal method with potassium permanganate (KMnO4) as the only raw material. By adjusting the initial concentration of KMnO4 solution and the time of the hydrothermal reaction, the morphology and crystallinity of δ-MnO2 can be controlled. The synthesized δ-MnO2 microspheres were characterized by XRD, SEM, TEM, TG/DSC, BET, ICP-AES and XPS. The catalytic ozonation performance of δ-MnO2 prepared by a hydrothermal reaction at 160 °C for 24 h using 0.1 mol L−1 KMnO4 solution was tested. Its catalytic activity is excellent. The degradation efficiencies of bisphenol A and ibuprofen using 0.1 g L−1 δ-MnO2 as the catalyst were 68.2% and 68.5% in 20 min reaction time. The results were much better than those of individual ozone treatment and with commercial MnO2 as the catalyst. The formation of hydroxyl radicals was not the main reason for the rapid degradation of organic compounds in the catalytic reaction with δ-MnO2 as the catalyst. The strong interaction among the catalyst surface, ozone and organic molecules was the important reason for catalysis based on the related experimental results.
研究领域:
环境科学
·
材料化学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF ENVIRONMENTAL ANALYTICAL CHEMISTRY
·
2019
·
IF 1.267
Kai Sun,Shun-Yao Li,Hui-Ling Chen,Qing-Guo Huang,Youbin Si
In this study, we used a simple and rapid colourimetric reaction for visual sensing of Fe2+ and Pb2+ ions in water by employing nano-MnO2 as a natural oxidase mimic to respectively catalyse ABTS and TMB in citrate-phosphate buffer solution (C-PBS) at 25°C and pH 3.8. It was found that nano-MnO2 possessed highly oxidase-mimicking activity with the Km values of 0.030 and 0.027 toward ABTS and TMB, respectively, indicating TMB had a stronger affinity on nano-MnO2 than ABTS. Interestingly, the presence of 0.01 mmol·L−1 Fe2+/Pb2+ ion was able to significantly down-regulate the activity of MnO2 nanozyme in nano-MnO2-mediated ABTS reaction processes (P < 0.01), which mainly due to the strong adsorption of metal ion toward nano-MnO2 surface via the electrostatic attractions, thus leading to the passivation and inactivation of MnO2 nanozyme catalytic activity. Thereinto, Fe2+ reacted with multivalent manganese by oxidation-reduction, while Pb2+ was specifically adsorbed onto the surface of MnO2 nanozyme and formed complexes. Notably, only Fe2+ ion inhibited the activity of MnO2 nanozyme-TMB with a detection limit as low as 1.0 μmol·L−1. In MnO2 nanozyme-ABTS sensing systems, Fe2+ and Pb2+ ions detection limit of 0.5 and 2.0 μmol·L−1 were, respectively, achieved with a linear response range of 0–0.02 and 0–0.8 mmol·L−1, implying the developed MnO2 nanozyme-ABTS sensor was potentially applicable for the visual determination of Fe2+ and Pb2+ ions in water. In the real water samples, MnO2 nanozyme-ABTS achieved high accuracy (relative errors: 3.4‒10.5%) and recovery (96‒110%) for respective detection of Fe2+ and Pb2+ ions. The simple and rapid MnO2 nanozyme-ABTS sensing systems might provide a practical assay for visual detection of Fe2+ and Pb2+ ions in the environmental water samples.
研究领域:
分析化学
·
环境科学
·
生物催化
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）