Journal of Energy Storage
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2021
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IF 6.583
Jie Xu,Cuili Xiang,Songwen Fang,Luping Zhu,Fen Xu,Lixian Sun,Yongjin Zou,Jian Zhang
Supercapacitors, such as pseudocapacitors (PCs), are widely used because of their excellent electrochemical activity and capacitance; however, it is still challenging to fabricate PCs with high stability and good electrochemical properties. Therefore, suitable templates and transition metal composite materials should be selected for improving their performance. Binary transition metal sulfides exhibit excellent electrochemical performance owing to their rich valence, electrical conductivity, and abundant electrochemical active sites. In this study, we prepared porous Mn-Co-S nanospheres (MCSN) via the hydrothermal method using silica colloidal particles was as the template; to the best of our knowledge, this is the first study to synthesize MCSN. Results suggest that the MCSN composite exhibited excellent conductivity and enhanced stability owing to the porous structure formed by the vertical growth of MnS 2 -CoS 2 nanosheets on silica nanoparticles. The porous MCSN electrode showed an excellent specific capacitance of 1158 F g −1 at 1 A g −1 . Moreover, when coupled with an activated carbon (AC) positive electrode, the supercapacitor of MCSN//AC exhibited stability of 90.4% after 5000 cycles at 10 A g −1 (the specific energy of 34 W h kg −1 at 775 W kg −1 ). Given the results, we believe that the prepared MCSN material has potential application prospects for high-efficiency supercapacitors.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
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2021
·Vol. 32
·期 10
·13430-13439
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IF 2.478
Kang Xiaoya,Ma Yingxia,Wang Jiawei,Shi Xiaofeng,Liu Binglu,Ran Fen
Metal organic frameworks (MOFs) have potential applications in the field of energy storage due to high specific surface area and rich porosity, and captured widely attention in recent years. In this work, nickel/manganese-based MOFs (Ni/Mn-MOFs) were successfully fabricated by solvothermal reaction using 1,4-phthalic acid as the organic ligand, nickel nitrate hexahydrate, and manganese nitrate tetrahydrate providing center metal ions. The Ni/Mn-MOFs were analyzed by scanning electron microscope, powder X-ray diffraction, and nitrogen absorption/desorption isotherm. The results indicate that the obtained Ni/Mn-MOFs have coral-like microstructures and hierarchical pores with a specific surface area of 380.8 m 2 /g and an average pore diameter of 13.6 nm. Subsequently, the Ni/Mn-MOFs were used as the electrode materials for supercapacitors, and the electrochemical properties were investigated in the three-electrode system using 6.0 M KOH aqueous solution as the electrolyte. The results show that the specific capacitances of the coral-like Ni/Mn-MOFs are 531.5 and 317.9 F/g at the current density of 0.5 and 5 A/g, respectively. And the capacitance retention is 67.7% after 2300 cycles at 5 A/g, which implies that the coral-like Ni/Mn-MOFs have higher specific capacitance and favorable cycle stability. The above results indicate that the coral-like Ni/Mn-MOFs facilitate the electrolyte infiltration and ions transportation.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2021
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IF 19.503
Zhe Chen,Xiaobin Liao,Congli Sun,Kangning Zhao,Daixin Ye,Jiantao Li,Gang Wu,Jianhui Fang,Hongbin Zhao,Jiujun Zhang
Constructing and excavating single atom catalysts with high-density active sites and long-life durability for energy storage and conversion devices still remain bestially challenges. In this paper, a novel dual-site electrocatalyst with atomically dispersed Fe/Mn-N x -C dual metal sites embedded in N-doped carbon matrix is successfully designed and synthesized, which exhibits a state-of-the-art oxygen reduction reaction (ORR) activity with a half-wave potential (E 1/2 ) of 0.88 V (vs. RHE) as well as a superior stability. Besides, the Fe/Mn-N x -C catalyst reaches a high power density of 208.6 mW cm −2 and a specific energy density of 825.5 W h kg -1 when this catalyst is employed in Zn-air battery, which is superior to most of the reported non-precious catalysts. Furthermore, theoretical DFT calculations reveal the excellent performance is induced through a synergic dual-site cascade mechanism, which overcomes the issue of low adsorption energy (E ads ) of *OH on Fe-N x site, followed by transfer of the *OH to adjacent Mn-N x sites. As a result, the first three steps during ORR more favored occur on the Fe-N x sites instead of the Mn sites to generate *OOH and *O intermediates due to the lower energy barriers. This mechanism is further approved by addition of methanol to verify the preferred adsorption of *OH on the Mn-N x site.
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JOURNAL OF MATERIALS SCIENCE
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2021
·Vol. 56
·期 34
·19155-19164
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IF 4.22
Fan Xuhui,Wang Jing,Rao Yu,Zhao Lei,Zhu Kongjun
Dielectric ceramics have attracted ever-increasing interest in energy storage applications due to their high-power density and fast charge–discharge speed. In particular, AgNbO 3 -based antiferroelectric ceramics are considered potential substitutes for lead-based ceramics. AgNbO 3 ceramics sintered with fine hydrothermal-synthesized powders show the advantage of high breakdown strength. However, the fine grains lead to the decreased polarization, which harms the recoverable energy density. In this work, a little amount over-stoichiometrical WO 3 and MnO 2 were introduced to synergistically improve the polarization and dielectric breakdown strength of obtained AgNbO 3 ceramics. The dependences of structures and dielectric properties on WO 3 doping were explored. A maximum polarization of 49.4 μC/cm 2 and E b as large as 285 kV/cm were achieved in 0.1 wt % WO 3 and MnO 2 co-doped AgNbO 3 ceramic. The corresponding W rec reached 2.75 J/cm 3 , which was 1.3 times larger than that of pristine AgNbO 3 ceramics. Moreover, benign thermal stability with W rec = 2.2–2.7 J/cm 3 over 30–150 °C at 240 kV cm −1 was also achieved in 0.1 wt.% WO 3 and MnO 2 co-doped AgNbO 3 ceramics.
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Materials
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2021
·Vol. 14
·期 9
·2238
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IF 3.623
Xiaoming Cao,Liyuan Gu,Shike Hu,Aiman Mukhtar,Kaiming Wu
A lot of nanomaterials are using T1-T2dual mode magnetic resonance (MR) contrast agents (CAs), but multilayer nanowire (NW) with iron (Fe) and manganese (Mn) as T1-T2dual modal CAs has not been reported yet. Herein, we synthesized a Fe/Mn multilayer NW with an adjustable Fe layer, as T1-T2dual-mode CAs. The relaxation performance of Fe/Mn multilayer NW was studied at 1.5 T. Results show that, when the length of the Fe layer is about 10 nm and the Mn is about 5 nm, the r1value (21.8 mM−1s−1) and r2value (74.8 mM−1s−1) of the Fe/Mn multilayer NW are higher than that of Mn NW (3.7 mM−1s−1) and Fe NW (59.3 mM−1s−1), respectively. We predict that our Fe/Mn multilayer NW could be used as T1-T2dual mode MRI CAs in the near future.Keywords:dual modal;MRI;CAs;nanowire;relaxation
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PubMed
高影响因子
Nanomaterials
·
2020
·Vol. 10
·期 9
·1745
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IF 4.324
Ze Sun,Liuting Zhang,Nianhua Yan,Jiaguang Zheng,Ting Bian,Zongming Yang,Shichuan Su
Magnesium hydride (MgH2) has been considered as a potential material for storing hydrogen, but its practical application is still hindered by the kinetic and thermodynamic obstacles. Herein, Mn-based catalysts (MnCl2and Mn) are adopted and doped into MgH2to improve its hydrogen storage performance. The onset dehydrogenation temperatures of MnCl2and submicron-Mn-doped MgH2are reduced to 225 °C and 183 °C, while the un-doped MgH2starts to release hydrogen at 315 °C. Further study reveals that 10 wt% of Mn is the better doping amount and the MgH2+ 10 wt% submicron-Mn composite can quickly release 6.6 wt% hydrogen in 8 min at 300 °C. For hydrogenation, the completely dehydrogenated composite starts to absorb hydrogen even at room temperature and almost 3.0 wt% H2can be rehydrogenated in 30 min under 3 MPa hydrogen at 100 °C. Additionally, the activation energy of hydrogenation reaction for the modified MgH2composite significantly decreases to 17.3 ± 0.4 kJ/mol, which is much lower than that of the primitive MgH2. Furthermore, the submicron-Mn-doped sample presents favorable cycling stability in 20 cycles, providing a good reference for designing and constructing efficient solid-state hydrogen storage systems for future application.Keywords:hydrogen storage;MgH2;Mn-based catalysts;catalytic effect;reversibility
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MATERIALS CHEMISTRY AND PHYSICS
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2020
·
IF 3.408
Tengyan Wu,Guokang Shen,Feng Ding,Duxin Li,Hongbin Zhong
In this study, the La doped Mn–Zn nanoferrites were synthesized through hydrothermal method , and then were used to activate persulfate for degrading azo dye the Direct Blue 15 (DB15). The structure and morphology of the as-prepared sample were characterized by X-ray Diffraction (XRD), Fourier Transformed Infrared Spectrometer (FTIR), Transmission Electron Microscopy (TEM) and Energy Dispersive Spectrometer (EDS). The results indicated that the La doped Mn–Zn ferrite was successfully synthesized in this study. Four absorption bands were observed in FTIR spectra and assigned to the corresponding site bonds. Mn 0.6 Zn 0.4 La x Fe 2- x O 4 was chosen as catalysts to activate persulfate (PS/Mn 0.6 Zn 0.4 La x Fe 2- x O 4 ) to decolorize the DB15. It was found that the DB15 was degraded effectively by PS/Mn 0.6 Zn 0.4 La x Fe 2- x O 4 systems. Furthermore, the influences of synthesized conditions (such as the temperature, holding time and doping content of La) of Mn 0.6 Zn 0.4 La x Fe 2- x O 4 on the DB15 decolorization were analyzed. The results indicated that the doping of La can significantly improve the DB15 degradation, 100% degradation of DB15 can be obtained by PS/Mn 0.6 Zn 0.4 La 0.09 Fe 1.91 O 4 within 15 min. The enhancement of synthesized holding time of Mn 0.6 Zn 0.4 La x Fe 2- x O 4 at 160 °C can also increase the DB15 decolorization, and the degradation rate of the DB15 reached almost 100% within 25 min when using Mn 0.6 Zn 0.4 La 0.05 Fe 1.95 O 4 synthesized at 160 °C for 13 h as catalyst.
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MATERIALS TECHNOLOGY
·
2020
·
IF 1.738
Huan Yang,Renxin Xu,Yaohui Zhao,Jian Cai
Mg0.2Mn0.8NdxFe2-xO4 (x = 0.000, 0.025, 0.050, 0.075 and 0.010) nano crystalline is synthesized via hydrothermal technique. Single cubic spinel phase is confirmed by XRD and the formation of Mg0.2Mn0.8NdxFe2-xO4 is verified by EDS. The average size of the nanoferrites is examined by TEM image. Nd3+ substituted Mg-Mn nanoferrites exhibit the low saturation magnetization (Ms) and high coercivity (Hc). The ferrite composites present that the resistivity and the magnetic loss are less than 2.8×107 Ω·cm and 0.75 in the range of 2-18 GHz, respectively. The optimized Mg0.2Mn0.8NdxFe2-xO4 (x=0.050) showed the minimum reflection loss of -39.80 dB at 1.4 GHz and effective absorption bandwidth (lower than -10 dB) of 7.58 GHz with a thickness of only 3 mm. The high coercivity, resistivity and excellent wave absorption performance indicate that the addition of Nd3+ contributes to the synthesis of the excellent soft magnetic materials and wave absorbing materials.
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Energy Technology
·
2020
·Vol. 8
·期 5
·2000008
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IF 3.404
Chengrui Wang,Lei Zhang,Yuhai Dou,Luke Hencz,Lixue Jiang,Mohammad Al-Mamun,Porun Liu,Shanqing Zhang,Dan Wang,Huijun Zhao
Further commercial application of low-cost NiO-based anodes is hindered by their large volume expansion after full lithiation and relatively poor theoretical capacity. To improve these issues, transition metal (Fe, Co, or Mn)-modified triple-shelled NiO microspheres (TS-NiO) are successfully synthesized by using a hard template double-adsorption method. Among them, the Fe-modified TS-NiO (TS-NFO) exhibits an extraordinary lithium storage ability with high reversible capacity and outstanding cycling stability (2061.1 mAh g −1 after 800 cycles at 0.5 A g −1 ), which is the highest performing nickel oxide-based anode reported to date. The outstanding electrochemical performance of TS-NFO can be ascribed to its unique triple-shelled structure. The inner core of TS-NFO is composed of NiO and is encapsulated by two outer shells which are composed of a mixture of α-Fe 2 O 3 and NiFe 2 O 4 , resulting in a unique hollow triple-shelled structure (NiO@α-Fe 2 O 3 /NiFe 2 O 4 ). The void space between the triple shells leaves room for their volume changes during lithiation/delithiation, which improves the cycling stability. In addition, the introduced α-Fe 2 O 3 /NiFe 2 O 4 outer shells increase the energy density and reversible capacity due to a synergistically interactive effect.
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JOURNAL OF THE AMERICAN CERAMIC SOCIETY
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2021
·Vol. 104
·期 11
·5547-5556
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IF 3.784
Jian Guo,Jianguo Chen,Jinrong Cheng,Qi Tan
Lead-free 0.75BiFeO 3 –0.25BaTiO 3 (0.75BF–0.25BT) ceramics have been extensively studied because of their high Curie temperature. The aging behavior and thermal stability of piezoceramics play decisive roles in their device applications. In this work, effects of Mn doping on the phase structure, aging behavior, and thermal stability of 0.75BF–0.25BT ceramics were characterized and related mechanisms were investigated. With the increase in Mn content, the typical rhombohedral phase of 0.75BF–0.25BT ceramics changed to the coexistence of pseudo-cubic and rhombohedral phases. Mn modification enhanced the aging behavior and thermal stability of ceramics obviously. The aging rates of d 33 and k p for 0.75BF-0.25BT ceramics with 1.0 mol% Mn are 1.3% and 1.1%, respectively, which are only 1/4 those values for the undoped ceramics. The variation of ε r of 0.75BF-0.25BT ceramics with 1.0 mol% Mn is half of undoped ceramics under 500℃. The depoling temperature of 0.75BF-0.25BT ceramics with 1.0 mol% Mn was 450℃, which is about 200℃ higher than that of undoped ceramics. The enhanced aging behavior results from the decreased defect concentrations, and the better thermal stability is owing to the significantly improved poling state due to the enhanced resistivity, large grain size, and decreased crystal distortion by Mn modification. These results reflect that a proper amount of Mn doping is an effective way to enhance the aging behavior and electric thermal stability.
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Journal of Environmental Chemical Engineering
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2021
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IF 5.909
Xuan Bie,Kai Wu,Kunling Jiao,Kun Zhao,Xiangyang Chen,Suangchen Ma
Generally, using transition metal oxides as catalysts is the typical method for ammonia-selective catalytic reduction (NH 3 -SCR) under the medium temperature zone (150–400 °C). The controllable structure and uniformly distributed active sites of (Fe&Mn)AlOx-based catalysts via a facilely operative and green prepared method were employed for high NO catalyzed efficiency and selectivity . Among them, the Mn 1.2 Al 0.8 O x sample exhibited excellent low-temperature activity, and Fe 1.2 Al 0.8 O x exhibited excellent N 2 selectivity, which could be ascribed to the unique surface feature (more redox sites on Mn 1.2 Al 0.8 O x and more acid sites on Fe 1.2 Al 0.8 O x ). This creative work has directly demonstrated the importance of coordination between the adsorption of species and electron transportation that emerged on active sites. Meanwhile, the reaction process has been clearly presented in in-situ DRIFTS, declaring the synergetic mechanism (Eley-Rideal mechanism and Langmuir-Hinshelwood mechanism) in the systems. The Eley-Rideal mechanism could be the dominant one due to its rapid reaction rate. The predictable insights are beneficial for profoundly understanding the dual-sites synergetic interaction for controllable conversion rate and high selectivity in the medium temperature SCR process.
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SENSORS AND ACTUATORS B-CHEMICAL
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2021
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IF 7.46
Cong Qin,Bing Wang,Yingde Wang
Improving the gas-sensing performances of p-type oxide semiconductors is an important research issue. Here, we reported the simple fabrication of bare Co 3 O 4 and Mn-doped Co 3 O 4 porous nanosheets by annealing the Co-based metal-organic frameworks (MOFs) nanosheets precursors synthesized from the ion-assisted solvothermal treatment. Different characterization techniques were adopted to verify the physical and chemical morphologies of the as-prepared samples. The results demonstrate that Mn cations have been successfully doped into the lattice of Co 3 O 4 . Besides, these prepared samples were used for detection of carbon monoxide (CO). Results show that 3 mol% Mn-doped Co 3 O 4 nanosheets present enhanced CO-sensing properties [(R g − R a )/R a = 280% to 40 ppm at 125 °C] compared with bare Co 3 O 4 nanosheets. The response reported here for the detection of CO even exceeds those of some n-type oxides under the same conditions. We speculate that the enhanced CO-sensing properties are probably due to the high specific surface area, abundant oxygen vacancies generated by Mn doping, and the relatively high Co 3+ /Co 2+ ratio. The Mn-doped Co 3 O 4 sensor has a huge potential advantage in detecting low concentrations of CO.
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