APPLIED CATALYSIS A-GENERAL
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2023
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IF 5.5
Jiacheng Xu,Tiantian Zhang,Yan Sun,Shiyu Fang,Zuliang Wu,Jiali Zhu,Lianxin Dai,Weihua Liu,Buhe Zhang,Junwei Zhang,Shuiliang Yao,Erhao Gao,Jing Li
MnO 2 is a promising catalyst due to its abundant metal valence and good redox ability. Different crystal phases of MnO 2 have different oxygen species, but the relationship between their catalytic activity and crystal structures is unclear. In this study, four MnO 2 catalysts with crystal structures ( α -, β -, γ -, and δ -MnO 2 ) were selected to unveil the roles of terminal-type (Mn O), superoxide-type Mn(-O-) 2 Mn, and bridge-type (Mn-O-Mn) oxygen species in CO oxidation . γ -MnO 2 has the best CO oxidation performance. Density functional theory calculation results show that Mn O on γ- MnO 2 can adsorb CO easier than other two types of oxygen species. Operando TPR-DRIFTS-MS results show that Mn O on the surface of γ- MnO 2 can react with CO to form terminal-type oxygen vacancies (M 2+ =□ 2– ) at low temperatures. Meanwhiles, Mn(-□-)(-O-)Mn and Mn-□-Mn can dissociate O 2 to form Mn O under certain conditions to promote CO oxidation. MnO 2 catalysts with more Mn O oxygen species are of great significance for CO oxidation at a low temperature.
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高影响因子
ACS Applied Materials & Interfaces
·
2022
·
IF 10.383
Qianlin Huang,Puzhen Zhao,Weiwei Wang,Lu Lv,Weiming Zhang,Bingcai Pan
Cost-efficient and durable manganese-based catalysts are in great demand for the catalytic elimination of volatile organic compounds (VOCs), which are dominated not only by the nanostructures but also by the oxygen vacancies and Mn–O bond in the catalysts. Herein, a series of nanostructured Co–Fe-doped-δ-MnO2 catalysts (Co–Fe-δ-MnO2) with high dispersion were in situ fabricated by employing metal–organic-frameworks (MOFs) as reducing agents, dopants, and templates all at the same time. The as-obtained Co–Fe-δ-MnO2-20% catalyst exhibited robust durability and high catalytic activity (225 °C) for toluene combustion even in the presence of 5 vol % water vapor, which is 50 °C lower than that of pristine δ-MnO2. Various characterizations revealed that the homogeneously dispersed codoping of Co and Fe ions into δ-MnO2 promotes the generation of oxygen vacancies and weakens the strength of the Mn–O bond, thus increasing the amount of adsorbed oxygen (Oads) and improving the mobility of lattice oxygen (Olatt). Meanwhile, due to successfully inheriting the framework structures of MOFs, the obtained catalyst exhibited a high surface area and three-dimensional mesoporous structure, which contributes to diffusion and increases the number of active sites. Moreover, in situ DRIFTS results confirmed that the toluene degradation mechanism on the Co–Fe-δ-MnO2-20% follows the MVK mechanism and revealed that more Oads and high-mobility Olatt induced by this novel method contribute to accumulating and mineralizing key intermediates (benzoate) and thus promote toluene oxidation. In conclusion, this work stimulates the opportunities to develop Co–Fe-δ-MnO2 as a class of nonprecious-metal-based catalysts for controlling VOC emissions.
研究领域:
环境科学
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材料科学
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高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2022
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IF 24.319
Menglu Xu,Yibing Zhang,Huaqin Yin,Jinnan Wang,Aimin Li,Philippe François-Xavier Corvini
Co-ZFO@Mn-CN with 1 O 2 and O 2 •− as main reactive oxygen species was synthesized for catalytic ozonation , which could efficiently degrade organic pollutants . EPR and XPS analysis indicated that lattice doping of Co induced formation of abundant of OVs, which could provide localized electrons for O 3 activation with the generation of HO 2 • /O 2 •− . 1 O 2 and H 2 O 2 were produced by the recombination of HO 2 • /O 2 •− . DFT calculation demonstrated that H 2 O 2 was deprotonated to generate HOO − , which preferred to form HOO-Mn-N X bonds with Co-ZFO@Mn-CN. Under the attack of O 3 , HOO-Mn-N X bonds were broken with the generation of HO 2 • and HO 3 • /O 3 •− , not only accelerating 1 O 2 production for organics degradation but also avoiding Mn(Ⅱ) sites oxidation . Combining advantages of OVs and HOO-Mn-N X , Co-ZFO@Mn-CN achieved 70–100% mineralization for different organic pollutants . Thus, this work provided a simple and efficient way for enhancing the utilization of O 3 by the synergistic effect of OVs and HOO-Mn-N X bonds, also improving ROS transformation.
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高影响因子
IONICS
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2023
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IF 2.8
Xiao Qingmei,Guo Ziting,Huang Jinchao,Zhong Shengwen
The development of efficient sodium-ion batteries is essential to overcome the issue of limited lithium sources for preparing lithium-ion batteries. Layered Mn-based cathode materials have significant application potential because of their simple structure and high specific capacities. Serious voltage attenuation and phase transition are the prominent problems of layered manganese-sodium ion batteries. To eliminate these issues, in this study, we investigated the effects of different Mn/Ni ratios in Na-Ni-Mn cathode materials on their structural stability and electrochemical performances. Na 0. 8MnO 2 (NNM-8010), Na 0.8 Ni 0.1 Mn 0.9 O 2 (NNM-819), Na 0.8 Ni 0.2 Mn 0.8 O 2 (NNM-828), and Na 0.8 Ni 0.3 Mn 0.7 O 2 (NNM-837) were synthesized and characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and electrochemical analyses. The addition of Ni 2+ increased the Mn oxidation state from + 3 to + 4, thus reducing the Jahn–Teller effect of Mn 3+ and stabilizing the material structure. NNM-819 exhibited the best electrochemical performance. Its initial discharge-specific capacity was 198.5mAh g −1 at a current density of 0.2C, and the capacity retention rate after 100 cycles was 86.9% at 0.5C. Moreover, its capacity retention rate at 1.0C high-rate cycling after 100 cycles remained high 81.9%. Graphical Abstract
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高影响因子
JOURNAL OF RARE EARTHS
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2020
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IF 3.104
Mei Li,Yongcheng Zhang,Haiming Li,Hailing Jiang,Wei Han,Yang Sun
In the present work, cyclic voltammetry (CV), square wave voltammetry (SWV) and chronopotentiometry (CP) were used to investigate the electrochemical coreduction behaviors of La(III) and Mg(II) as well as La(III), Mg(II) and Mn(II) on Mo electrode in LiCl + KCl molten salts. CV and SWV results exhibit that the coreduction mechanism of La (III) and Mg(II) on Mo electrode is that La(III) is reduced and Mg–La intermetallic compound is formed, leading to the deposition potential of La(III) shifting to more positive one. The electrochemical signals pertaining to the formation of metallic La, Mg and Mn as well as Mg–La intermetallic compound are also observed by coreduction of La(III), Mg(II), and Mn(II) in LiCl + KCl molten salt on the inert Mo electrode. However, the electrochemical signals associated with the formation of La–Mn and Mg–Mn alloys are not observed, which means that the depolarization effect of La(III) and Mg(II) does not occur on pre-deposited Mn electrode. The Mg–La–Mn alloys were formed by co-deposition of La(III), Mg(II), and Mn(II) on Mo electrode at various concentration ratios of La(III) and Mg(II). The results of scanning electron microscopy equipped with energy dispersive spectroscopy and X-ray diffraction displays that the Mg–La–Mn alloys are comprised of La–Mg compound Mg 17 La 2 , Mg and Mn phases. The concentration ratio of La(III) and Mn(II) has few effects on the alloy composition .
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高影响因子
TALANTA
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2016
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IF 4.035
Songqing Chen,Xingxiu Qin,Weixi Gu,Xiashi Zhu
Ionic liquids-β-cyclodextrin polymer (ILs-β-CDCP) was attached on Fe 3 O 4 nanoparticles to prepare magnetic solid phase extraction agent (Fe 3 O 4 @ILs-β-CDCP). The properties and morphology of Fe 3 O 4 @ILs-β-CDCP were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction(XRD), size distribution and magnetic analysis. A new method of magnetic solid phase extraction (MSPE) coupled to ICP-OES for the speciation of Mn(II)/Mn(VII) in water samples was established. The results showed that Mn(VII) and total manganese [Mn(II)+Mn(VII)] were quantitatively extracted after adjusting aqueous sample solution to pH 6.0 and 10.0, respectively. Mn(II) was calculated by subtraction of Mn(VII) from total manganese. Fe 3 O 4 @ILs-β-CDCP showed a higher adsorption capacity toward Mn(II) and Mn(VII). Several factors, such as the pH value, extraction temperature and sample volume, were optimized to achieve the best extraction efficiency. Moreover, the adsorption ability of Fe 3 O 4 @ILs-β-CDCP would not be significantly lower after reusing of 10 times. The accuracy of the developed method was confirmed by analyzing certified reference materials (GSB 07-1189-2000), and by spiking spring water, city water and lake water samples.
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PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2024
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IF 8.1
Xiaoying Zhou,Shiyu Fang,Tiantian Zhang,Zuliang Wu,Jing Li,Wei Wang,Jiali Zhu,Junliang Wu,Daiqi Ye,Rui Han,Qingling Liu,Shuiliang Yao,Erhao Gao,Dayu Wu
The development of non-noble metal catalysts for low-temperature CO oxidation is a pivotal subject in various disciplines. In this study, an optimized Mn-doped NiO catalyst (Mn-NiO-0.5), prepared via aerosol pyrolysis with an equal molar ratio of Ni to Mn, demonstrates remarkable performance. It achieves an 82 % CO conversion at -20 °C and a 100 % conversion between 10 °C and 800 °C. The catalyst’s turnover frequency ( TOF ) for CO oxidation significantly surpasses that of previously reported noble-metal-based catalysts, underscoring its superior efficiency. Dynamic analyses suggest that the enhanced catalytic activity is a result of the unique atom burr structure, which presents an extensive surface area replete with abundant active sites. This structural feature is instrumental in maximizing the catalyst’s interaction with CO molecules. Experimental findings, corroborated by density functional theory (DFT) calculations, elucidate the mechanism of CO oxidation on the Mn-NiO-0.5 catalyst. The process is facilitated by the synergistic action of bimetallic sites, where the Ni–OH site acts as the primary adsorption point for CO. Subsequently, the CO is oxidized to bicarbonate through the interaction with the oxygen (O or O 2 ) at adjacent Mn sites. This pioneering study introduces a paradigm-shifting insight: the effectiveness of non-noble metal oxide catalysts can now compete with, and in some cases, outperform their noble metal counterparts. This breakthrough is set to transform the industry, presenting a compelling alternative to conventional noble metal catalysts and propelling the evolution of state-of-the-art environmental conservation technologies.
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Research
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2022
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IF 11.036
Xuefei Xu,Qingming Deng,Hsiao-Chien Chen,Muhammad Humayun,Delong Duan,Xia Zhang,Huachuan Sun,Xiang Ao,Xinying Xue,Anton Nikiforov,Kaifu Huo,Chundong Wang,Yujie Xiong
Electrocatalytic urea oxidation reaction (UOR) is regarded as an effective yet challenging approach for the degradation of urea in wastewater into harmless N2 and CO2. To overcome the sluggish kinetics, catalytically active sites should be rationally designed to maneuver the multiple key steps of intermediate adsorption and desorption. Herein, we demonstrate that metal-organic frameworks (MOFs) can provide an ideal platform for tailoring binary active sites to facilitate the rate-determining steps, achieving remarkable electrocatalytic activity toward UOR. Specifically, the MOF (namely, NiMn0.14-BDC) based on Ni/Mn sites and terephthalic acid (BDC) ligands exhibits a low voltage of 1.317 V to deliver a current density of 10 mA cm-2. As a result, a high turnover frequency (TOF) of 0.15 s-1 is achieved at a voltage of 1.4 V, which enables a urea degradation rate of 81.87% in 0.33 M urea solution. The combination of experimental characterization with theoretical calculation reveals that the Ni and Mn sites play synergistic roles in maneuvering the evolution of urea molecules and key reaction intermediates during the UOR, while the binary Ni/Mn sites in MOF offer the tunability for electronic structure and d-band center impacting on the intermediate evolution. This work provides important insights into active site design by leveraging MOF platform and represents a solid step toward highly efficient UOR with MOF-based electrocatalysts.
研究领域:
材料科学
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电化学
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催化科学
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高影响因子
ACS Applied Materials & Interfaces
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2017
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IF 7.504
Daqin Chen,Gaoliang Fang,Xiao Chen
Tunability of emitting colors of perovskite quantum dots (PQDs) was generally realized via composition/size modulation. Due to their bandgap absorption and ionic crystal features, the mixing of multiple PQDs inevitably suffers from reabsorption and anion-exchange effects. Herein, we address these issues with high-content Mn2+-doped CsPbCl3 PQDs that can yield blue-excitable orange Mn2+ emission benefited from exciton-to-Mn energy transfer and Cl-to-Br anion exchange. Silica-coating was applied to improve air stability of PQDs, suppress the loss of Mn2+, and avoid anion-exchange between different PQDs. As a direct benefit of intense multicolor emissions from Mn2+-doped PQD@SiO2 solid phosphors, a prototype white light-emitting diode with excellent optical performance and superior light stability was constructed using green CsPbBr3@SiO2 and orange Mn: CsPb(Cl/Br)3@SiO2 composites as color converters, verifying their potential applications in the field of optoelectronics.
研究领域:
材料科学
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光电技术
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纳米技术
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光子学
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DOI
高影响因子
CHEMOSPHERE
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2022
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IF 8.943
Yanchao Li,Can Wang,Shuang Pan,Xin Zhao,Ning Liu
Fe/Mn@carbon cloth (CC) was successfully fabricated through high-temperature shock (HTS) technique and used as cathode modification in heterogeneous electro-Fenton (hetero-EF) process for methylisothiazolinone (MIT) degradation. The nanocrystalline on Fe/Mn@CC electrode is doped with Fe and Mn oxides and coated with carbon layer, which could markedly enhance the electrocatalysis with high electro-chemical active area and low resistance. Fe/Mn@CC modified cathode can efficiently in-situ produce and activate H 2 O 2 , showing high electrocatalytic activity to MIT degradation. The 95.2% MIT degradation with in 100 min were achieved under the condition of 30 mA current, 0.75 L min −1 aeration intensity and initial pH = 3. Based on the CV curves and stability test, the high degradation activity revealed the kinetically beneficial regeneration of Fe II /Mn II in Fe/Mn@CC and activation of H 2 O 2 . The electron transfer between Fe II/III and Mn II/III , together with the direct Fe II /Mn II regeneration on the cathode, could markedly promote the H 2 O 2 utilization, and eventually lead to MIT degradation.
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PubMed
高影响因子
CERAMICS INTERNATIONAL
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2019
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IF 3.45
Fan Feng,Yan Yan
The electric field in ferroelectric ceramics can induce notable deformations or strains based mainly on the electrostrictive effect if the driving field is sufficiently large (normally larger than the coercive field). Therefore, a large electrostrictive effect is highly desired to achieve a high strain output. In the present work, 0.5Ba(Zr 0.2 Ti 0.8 )O 3 -0.5(Ba 0.7 Ca 0.3 )TiO 3 (BCZT50) ferroelectric ceramics doped with different numbers of Mn ions were synthesized and their dielectric and ferroelectric properties were studied to comprehensively evaluate the electrostrictive effect in this system. The doping levels were set as 0.0025, 0.005, 0.01, and 0.02. It was found that Mn ions could lower the temperature corresponding to the maximum permittivity, T m , drastically and induce diffuse phase-transition behaviors simultaneously. Most importantly, a purely electrostrictive effect with a longitudinal electrostrictive coefficient, Q 33 , as large as 0.0466 m 4 /C 2 was observed between 22 and 80 °C. The Q 33 of Mn-doped BCZT50 ceramics is much higher than some representative lead-based and lead-free ferroelectric ceramics. In this paper, a potential lead-free ferroelectric system with a large electrostrictive effect, which has potential applications in electrostrictive actuators, is reported.
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高影响因子
OPTIK
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2019
·
IF 1.914
Benze Wu,Jin Li,Qiang Li
The Mn-doped nano-ZnO powder was successfully synthesized via co-precipitation and vacuum annealing and the scanning electron microscopy (SEM), X-ray diffracton (XRD), ultraviolet visible absorption (Uv–vis) and photoluminescence (PL) of as-synthesized samples were characterized. The SEM and XRD show that the morphology of the synthesized samples was wurtzite nanosheets and nanoparticles at low doping concentration and with increasing Mn-doping concentration, mainly became to nanoparticle with a size of about 50nm. All of the ultraviolet absorption edges of Mn-doped ZnO have blue shift from Uiv-vis spectra and PL spectra show that Mn-doping significantly enhance the visible excitation band compared with pure ZnO, which indicates that Mn-doping not only produces elemental energy levels, but also affects the intrinsic defect energy levels of ZnO.
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