ACS Applied Materials & Interfaces
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2022
·
IF 10.383
Yuming Xi,Yangcheng Lu
In this work, for the performance enhancement of iron hexacyanoferrate, an electrochemically active Mn-doped iron hexacyanoferrate cathode is fabricated via a bottom-up approach. It is found that the pre-treatment of interstitial water and appropriate Mn doping are two keys to achieving higher capacity and higher stability. The interstitial water has a trade-off effect between the alleviation of volume expansion upon Na+ (de)intercalation and the retardation of Na-ion diffusion. The moisture-tailored iron hexacyanoferrate with appropriate Mn doping exhibits a high initial Coulombic efficiency of 94.8%, enhanced capacity and rate performance, and excellent cycling stability. These results benefit from the fact that the extraction/insertion of Na ions from/into the lattice via a solid-solution mechanism correspond to both the slight volume expansion and fast sodium diffusion rate; otherwise, the removal of interstitial water and a higher Mn content might lead to poor cycling stability due to excessive volume expansion resulting from rhombohedral to cubic phase transformation. Finally, the less demand on the control of air humidity for the fabrication of electrodes and the potential for the full cell coupled with hard carbon are also demonstrated, which shows great potential for practical applications.
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高影响因子
Sustainable Chemistry and Pharmacy
·
2022
·
IF 5.464
Zhenwei Zhang,Xiaoshi Ma,Chuanjun Yue,Xuejiao Wei,Baoliang Liu,Xiaohui Chen
Hazardous waste alkaline batteries and waste fatty acids significantly threaten the environment. In this study, waste alkaline batteries were simply transferred to r-MnZn catalysts, which were then applied in the ketonization of fatty acids. The assessment results show that r-MnZn can efficiently convert n-octanoic acid to 8-pentadecanone. The conversion and yield are evaluated as 100% and 92.9%, respectively, which are much better than those of TiO 2 , ZrO 2 , CeO 2 and other metal oxides . The excellent catalytic efficiency is derived from the MnO 2 nanorods in r-MnZn materials which are characterized by XRD, TEM, and XPS. In addition, when using different kinds of fatty acids in ketonization, longer carbon chains require a higher activation energy, and the conversion of fatty acids was lower. Furthermore, the ketone products have a short carbon chain that induces side reactions, leading to a low yield. The above results indicate that r-MnZn is an efficient catalyst applied in the ketonization of fatty acids.
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NANOTECHNOLOGY
·
2022
·Vol. 33
·期 45
·455703
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IF 3.953
Lei Wang,Hengbin Mao,Junhui Li,Yi Li,Mingliang Li,Jinpeng Zhu,Bingbing Fan,Wen Liu,Gang Shao,Hongliang Xu,Hailong Wang,Rui Zhang,Hongxia Lu
CsPbX3 (X = Cl, Br, I) semiconductor nanocrystals (NCs) have excellent optical and photoelectric properties, and are potential core materials for various photoelectric devices. However, the toxicity of Pb and instability have been the key limitations to application of NCs. Herein, using MnBr2 and MnBr2·4H2O as manganese sources, heavy Mn-doped CsPbBr3 (Mn:CsPbBr3) NCs are synthesized by high-energy ball grinding, which avoids high temperature, a large number of polar solvents and atmosphere protection required in traditional liquid phase methods. However, when MnBr2·4H2O is used as the raw material, infinite solid solution doping can be achieved, and the synthesized Mn:CsPbBr3 NCs show smaller particle size, stronger PL intensity and stability. The reason is that presence of crystal water plays a similar role to wet milling in the ball milling process, and can promote the passivation effect of oleylamine (OAm) on nanocrystal defects and the connection between them. In addition, a simple, easy-operating and beneficial to commercial production method for the preparation of Mn:CsPbBr3 NCs/EVA flexible films is proposed, which can effectively improve the stability of Mn:CsPbBr3 NCs. This study is expected to provide an effective way for the synthesis and stability improvement of CsPbX3 NCs doped with different ions.
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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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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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Journal of Energy Storage
·
2021
·
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 Environmental Chemical Engineering
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2021
·
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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SURFACE & COATINGS TECHNOLOGY
·
2021
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IF 4.158
Yan Yan,Jiale Guo,Nuo Chen,Yuxin Song,Si Wu,Qi Zhang,Qiang Han,Ming Gao,Jinghai Yang,Jihui Lang
Mn-TiO 2 /carbon cloth (CC) membranes with various Mn doping concentrations have been synthesized by hydrothermal process for efficient oil-water separation. The prepared membranes with superhydrophilic in air and underwater superoleophobic have the excellent self-cleaning performance under visible light driven, and these performances are strongly influenced by Mn doping concentration. The separation efficiency of the membranes is above 98% even after 56 oil-water separation cycles for various oil-water mixtures due to the d-states hybridization of Mn ions. Importantly, the membranes also have the good mechanical performance, reusability, chemical durability, and even work in acid, alkali and salt environment. The aforementioned properties and the easily scale-up production technique ensure that the Mn-TiO 2 /CC membrane has a potential application in practical treatment of oil spillage clean-up and oily wastewater.
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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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Materials
·
2021
·Vol. 14
·期 9
·2238
·
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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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
·
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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