APPLIED SURFACE SCIENCE
·
2024
·
IF 6.3
Siwen Gong,Gangqiang Zhu,Xiaoqian Xie,Fei Rao,Lujun Zhu,Yurong An,Xianjin Shi,Yu Huang,Peng Liu,Mirabbos Hojamberdiev
A novel interface of MnO 2 with CuO with multivalent conversion is fabricated by the deposition-precipitation method for low-temperature and efficient CO oxidation. It is found that the temperature for CO thermal-catalytic oxidation to reach a complete conversion significantly decreases to 105 °C for the CuO/MnO 2 . A combination of experimental and theoretical studies demonstrates the successful formation of the CuO/MnO 2 interface, inducing a pronounced effect that promotes CO oxidation. The CuO/MnO 2 interface leads to the formation of Cu-O-Mn, a superior redox system with multivalent conversion (Cu + + Mn 4+ ↔ Cu 2+ + Mn 3+ , Cu + + Mn 3+ ↔ Cu 2+ + Mn 2+ ), abundant active sites, excellent ability to activate O 2 , the rapid oxygen transfer, and more suitable adsorption energy for O 2 , CO, and CO 2 . These characteristics are advantageous to Cu x O-Mn x O y for achieving a 100 % removal of CO at a lower temperature. Furthermore, the computational study reveals that the CO oxidation process follows two mechanistic pathways (Eley-Rideal (E-R) and Mars-van Krevelen (M-K)), indicating that there is no competitive adsorption of CO and O 2 on the CuO/MnO 2 . This study shows that the interface created between suitable metal oxides can improve the catalytic performance and provides new perspective for catalyst design and performance enhancement mechanisms.
研究领域:
材料科学
·
催化化学
✓ 已验证
DOI
高影响因子
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
·
2020
·
IF 2.717
Yanglin Zhang,Xi'an Fan,Wentao Hu,Zigui Luo,Zhenjia Yang,Guangqiang Li,Yawei Li
In this paper, Fe soft magnetic composites (SMCs) coated with MnO 2 were prepared successfully by ball milling and following spark plasma sintering. The effect of MnO 2 content on microstructure and magnetic properties for the Fe/MnO 2 SMCs was investigated in detail. The analysis results show that a uniform MnO 2 coating layer can be formed on the surface of the Fe particles via low speed ball milling with agate balls. When the MnO 2 content increases from 0.0 wt% to 10.0 wt%, the thickness of the MnO 2 coating layer exhibits a growth trend. As a consequence, the increased nonmagnetic phase leads to the magnetic dilution, finally resulting in the reduced saturation magnetization and deteriorated coercivity. Moreover, the enhanced resistivity induced by the increased thickness, significantly reduces the generation of the inter-particle eddy current, which leads to more stable permeability and lower total core loss at high frequencies. This study provides a novel insulating coating layer to reduce total core loss and is advantageous for the development of iron-based SMCs.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Zhenda Liang,Haiqing Wang,Kena Zhang,Ge Ma,Lishan Zhu,Li Zhou,Bing Yan
Low-cost MnO 2 has been vigorously investigated in the field of catalysis. However, high amount of MnO 2 usually needs to be used in the disinfection process owing to their low photocatalytic activity. In this work, modification of MnO 2 with zeolitic imidazole framework-8 (ZIF-8) for improving the photocatalytic bactericidal performance was explored for the first time. Specifically, MnO 2 /ZIF-8 exhibited complete inactivation of multi-drug resistant Escherichia coli ( E. coli) at a low concentration (3.24 μg/mL) with simulated solar irradiation. The 1 O 2 rather than O 2 − or OH was identified as the major reactive species for the bacterial inactivation. Mechanistic studies indicated that the superior bactericidal property of MnO 2 /ZIF-8 than the pristine material could be ascribed to the increased surface oxygen vacancies (OVs) amount and an inhibited electron and hole recombination. This study provides a novel type of photocatalyst for antibacterial application and may shed light on designing MnO 2 based low-cost nanocomposites with photocatalytic bactericidal capability for the practical water disinfection treatment.
研究领域:
环境科学
·
材料科学
·
微生物学
✓ 已验证
DOI
高影响因子
ELECTROCHIMICA ACTA
·
2020
·
IF 6.215
Gang Liu,Lin Ma,Qiming Liu
The attempt of high output potential character has always been an enormous challenge for water-based supercapacitors. In this paper, we first synthesize leaf-like Co 3 O 4 @MnO 2 nanosheets on the carbon cloth fibers (Co 3 O 4 @MnO 2 CC) with hierarchical core-shell structure via a facile chemical bath deposition at low temperature. This leaf-like Co 3 O 4 @MnO 2 nanosheets not only afford the advantage of ultra-high output potential (1.2 vs (Ag/AgCl)/V), but also carry the superiorities of ultra-high specific capacitance (616.7 F g −1 at 2 A g −1 ) and remarkable cyclic stability (83.1% retention after 10000 cycles at 20 A g −1 ). The asymmetrical supercapacitor, assembled by using Co 3 O 4 @MnO 2 @CC-90 (CoMn@CC-90) as cathode and active carbon (AC) as anode, exhibits multiple merits of extra-high output potential (2.2 V vs AC/V), splendid specific energy (54.71 W h kg −1 at power density of 1.06 k W kg −1 ) and long cycle life (86.3% capacitance retention after 10000 cycles). Our work offers one novel kind of reference for water-based supercapacitors with both characteristics of high output potential and high specific capacitance.
研究领域:
材料科学
·
能源存储技术
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Xuejie Yue,Tao Zhang,Dongya Yang,Fengxian Qiu
Flexible ceramic material, as a fundamental component of a toolset for the design of multifunctional materials, is very desirable, but a simple and effective preparation strategy is still missing. Herein, a flexible Si 3 N 4 /MnO 2 ceramic membrane was fabricated by facile vacuum filtration progress using hard Si 3 N 4 particles and soft ultralong MnO 2 nanowires as building blocks. The Si 3 N 4 particles were uniformly anchored into the porous flexible membrane, depending on the mechanical entanglement from ultralong MnO 2 nanowires, resulting in the excellent interface stability between them. Thanks to the flexibility of MnO 2 nanowires and interface stability, the as-prepared flexible membrane achieves superior flexibility including bending, folding, and twining. The flexible ceramic membrane can broaden the application range beyond the traditional ceramic use as hard structural materials. Moreover, the design strategy developed herein is applicable to other hard ceramic with similar issues.
研究领域:
材料科学
·
纳米技术
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2017
·Vol. 5
·期 12
·5719-5725
·
IF 8.867
Jinlong Wang,Gaoke Zhang,Pengyi Zhang
Catalytic reaction active sites tend to be structural defects, such as edges, corners and ribs which have a low coordination number. Here, a kind of layered MnO2 (birnessite) with irregular surface pits was successfully synthesized and investigated for the catalytic oxidation of formaldehyde. The surface pits were generated by a series of chemical surface modifications. Tetrabutylammonium hydroxide (TBAOH) played a key role in generating surface pits, which entered the interlayer from the edge of acid-treated MnO2 and weakened the van der Waals force between interlayers. The steric effects of TBAOH lead to the generation of irregular surface pits. The presence of surface pits not only provided larger specific surface areas but also led to more unsaturated manganese and oxygen atoms, which promoted formaldehyde adsorption and oxygen activation. As a result, birnessite-type MnO2 with surface pits exhibited a lower apparent activation energy than the pristine one (37.6 versus 55.4 kJ mol−1) for 200 ppm of HCHO under a GHSV of 120 000 mL g−1 h−1 and ∼45% relative humidity. These findings open up a new way to generate surface pits on layered 2D materials, holding promise for designing highly efficient catalysts by creating active centers.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2018
·
IF 6.735
Zhengyu Dong,Qian Zhang,Bor-Yann Chen,Junming Hong
A novel and high-efficiency Fe 3 O 4 -α-MnO 2 nanoflower-like catalyst was synthesized using a two-step hydrothermal method. The catalyst was used to activate persulfate (PS) to degrade bisphenol A (BPA) in aqueous phase. The mechanism of the Fe 3 O 4 -α-MnO 2 /PS system was investigated. X-ray photoelectron spectra and cyclic voltammograms showed that the mixed valence of Fe 3 O 4 -α-MnO 2 was favorable to electron transfer between Fe and Mn elements. Apparently, this process promoted the circulation of Fe 2+ /Fe 3+ and Mn 3+ /Mn 4+ , increasing the effectiveness of the catalyst to activate the PS. In addition, with ATR-FTIR analysis, the influence of phosphate confirmed the presence of OH groups on the Fe 3 O 4 -α-MnO 2 surface. Thus, these groups played crucial roles in the PS activation . Sulfate radicals were reacting species of great importance in BPA degradation. The degradation intermediates were also detected via GC–MS analysis, and the possible BPA degradation pathway was proposed.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
Nano-Micro Letters
·
2019
·Vol. 11
·期 1
·1-12
·
IF 9.043
Wang Siliang,Wang Qiang,Zeng Wei,Wang Min,Ruan Limin,Ma Yanan
Restricted by their energy storage mechanism, current energy storage devices have certain drawbacks, such as low power density for batteries and low energy density for supercapacitors. Fortunately, the nearest ion capacitors, such as lithium-ion and sodium-ion capacitors containing battery-type and capacitor-type electrodes, may allow achieving both high energy and power densities. For the inspiration, a new zinc-ion capacitor (ZIC) has been designed and realized by assembling the free-standing manganese dioxide–carbon nanotubes (MnO 2 –CNTs) battery-type cathode and MXene (Ti 3 C 2 T x ) capacitor-type anode in an aqueous electrolyte. The ZIC can avoid the insecurity issues that frequently occurred in lithium-ion and sodium-ion capacitors in organic electrolytes. As expected, the ZIC in an aqueous liquid electrolyte exhibits excellent electrochemical performance (based on the total weight of cathode and anode), such as a high specific capacitance of 115.1 F g −1 (1 mV s −1 ), high energy density of 98.6 Wh kg −1 (77.5 W kg −1 ), high power density of 2480.6 W kg −1 (29.7 Wh kg −1 ), and high capacitance retention of ~ 83.6% of its initial capacitance (15,000 cycles). Even in an aqueous gel electrolyte, the ZIC also exhibits excellent performance. This work provides an essential strategy for designing next-generation high-performance energy storage devices.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2022
·
IF 10.53
Xuesong Ye,Jun Nan,Zhencheng Ge,Qiliang Xiao,Bohan Liu,Yujie Men,Jinyong Liu
Low-pressure ultrafiltration membrane (LPM) is an ideal technology for decentralized water supply. However, the applicability for removing ferrous iron (Fe 2+ ), manganese (Mn 2+ ), and ammonia (NH 4 + ) in the source water and related mechanisms remained unknown. To fill this major knowledge gap, we systematically compared the pristine (pr-LPM) and MnO 2 -preloaded membrane (Mn-LPM). Mn-LPM allowed higher water flux while enhancing the removal of Fe 2+ , Mn 2+ , and NH 4 + . The removal efficiency of Mn 2+ immediately reached 99.6% on the first day. The preloading of MnO 2 also enhanced the removal capacity of NH 4 + . A series of instrument characterizations suggest that a higher NH 4 + concentration resulted in a thicker bio-cake layer, correlating to the higher pollutant removal efficiency and the decrease in the stable flux. Under high NH 4 + concentrations, Anaerobic Ammonia Oxidation likely contributes to NH 4 + removal. These findings significantly improve the understanding and help the design of LPM systems for cost-effective decentralized water supply in remote areas.
研究领域:
环境科学
·
水处理工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2023
·
IF 9.9
Yuantao Li,Jiajun Zhu,Jiyang Xie,Yongyun Mao,Wanbiao Hu
Constructing three-dimensional (3D) hierarchical bimetallic pseudocapacitive materials with abundant opening channel and heterojunction structures is rather promising but still challenging for high-performance supercapacitors. Herein, a self-sacrifice-template epitaxial growth strategy was proposed for the first time to construct 3D hierarchical bimetallic pseudocapacitive material. By using this strategy, NiCo 2 O 4 nanowires (NiCo 2 O 4 NW) arrayed randomly to form a porous shell via in-situ epitaxial growth fully enclosing a MnO 2 tube core, forming multiple transport channels and nano-heterojunctions between MnO 2 and NiCo 2 O 4 NW, which facilitates electron transfer, i.e. exhibiting high electronic conductivity than any single component. As a result of the self-sacrifice-template epitaxial growth method, special hollow tectorum-like 3D hierarchical structure with considerable inter-nanowire space and hollow interior space enables easy access of electrolyte to NiCo 2 O 4 NW surface and MnO 2 core, thereby resulting in highly exposed redox active sites of MnO 2 core and NiCo 2 O 4 NW shell for energy storage. Comprehensive evaluations confirmed MnO 2 @NiCo 2 O 4 NW was a supercapacitor electrode candidate, delivering a superior energy density of 106.37 Wh kg −1 . Such performance can be ascribed to the synergistic coupling effect of 3D hierarchical tube and nano-heterojunction structures. The proposed self-sacrifice-template epitaxial growth strategy provides important guidance for designing high-performance energy storage materials.
研究领域:
材料科学
·
储能技术
·
纳米材料
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Frontiers in Chemistry
·
2021
·
IF 5.221
Tang Shurong,Liu Qiao,Hu Jie,Chen Wei,An Fengping,Xu Hui,Song Hongbo,Wang Yi-Wei
In this paper, we developed a quick, economical and sensitive colorimetric strategy for copper ions (Cu2+) quantification via the redox response of MnO2 nanosheets with glutathione (GSH). This reaction consumed MnO2 nanosheets, which acted as a catalyst for the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to a blue product (oxTMB). In the presence of Cu2+, the GSH was catalyzed to GSSG (oxidized glutathione), and the solution changed from colorless to deep blue. Under the optimum conditions, the absorption signal of the oxidized product (oxTMB) became proportional to Cu2+ concentration in the range from 10 to 300 nM with a detection limit of 6.9 nM. This detection system showed high specificity for Cu2+. Moreover, the system has been efficaciously implemented for Cu2+ detection in actual tap water samples. The layered-nanostructures of MnO2 nanosheets make it possess high chemical and thermal stability. TMB can be quickly oxidized within 10 min by the catalyzing of MnO2 nanosheets with high oxidase-like activity. There is no need of expensive reagents, additional H2O2 and complicated modification processes during the colorimetric assay. Therefore, the strategy primarily based on MnO2 nanosheets is promising for real-time, rapid and highly sensitive detection of Cu2+ under practical conditions.
研究领域:
分析化学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2023
·
IF 7.2
Minghua He,Zulhumar Turup,Xuekun Jin,Fengjuan Chen
MnO 2 is considered to be one of the most promising electrocatalysts for oxygen reduction reactions (ORR) in alkaline media and can be applied to various electrochemical energy conversion and storage devices. However, it is limited by the relatively slow kinetics of the cathodic electrochemical reactions . In addition, it is difficult to control the presence state of Ag during the modification of MnO 2 . To this end, an efficient ORR electrocatalyst of Ag nanoparticles supported by MnO 2 nanorods was successfully synthesized by using NH 3 ·H 2 O as a complexing agent to inhibit the Ag + intercalating into the tunnels of MnO 2 . The half-wave potential ( E 1/2 ) and limiting current density ( J lim ) of the obtained Ag/MnO 2 electrocatalysts are 0.81 V and −5.6 mA cm −2 , respectively, showing comparable ORR catalytic activity to commercial Pt/C catalysts. The excellent catalytic performances can be attributed to the presence of abundant oxygen vacancies and Mn 3+ species on the MnO 2 surface, as well as the synergistic effect between MnO 2 substrates and Ag nanoparticles. Among them, oxygen vacancies enhances the adsorption of O 2 , Mn 3+ facilitates the displacement of O 2 2− /OH − , MnO 2 inhibits the accumulation of peroxide species to improving the oxygen environment on the Ag surface and Ag accelerates the electron transfer in the whole process. This work provides a useful guide for the design of efficient Mn-based ORR electrocatalysts.
研究领域:
材料科学
·
电化学
✓ 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）