Nano Energy
·
2019
·
IF 15.548
Biwei Wang,Jinxiang Zou,Xiaochen Shen,Yuchi Yang,Guangzhi Hu,Wei Li,Zhenmeng Peng,Dustin Banham,Angang Dong,Dongyuan Zhao
Iron-nitrogen-carbon (Fe-N-C) materials featuring Fe-N 4 moieties are promising candidates to replace commercial Pt/C catalysts for the oxygen reduction reaction (ORR). Here we report a novel Mn-Fe-N/S@mC catalyst comprising atomically dispersed Fe-N 4 sites and a trace amount of Mn-N 2 S 2 sites, which are homogeneously anchored on an ordered mesoporous graphitic carbon framework. This dual-metal catalyst is realized based on the chemical conversion of self-assembled Mn 0.43 Fe 2.57 O 4 nanocrystal supracrystals, with the dual metal sites and the graphitic framework derived from nanocrystal cores and the associated capping ligands, respectively. When evaluated as electrocatalysts for the ORR, Mn-Fe-N/S@mC exhibits excellent catalytic activity in alkaline media , outperforming conventional Pt/C and most non-precious-metal catalysts reported previously. Notably, the synergistic effect of having Fe and Mn together improves the catalytic activity by a factor of ~ 5. To better understand the high efficiency of Mn doping in enhancing the activity of Fe-N 4 sites, density functional theory calculations were carried out, revealing that the synergistic interaction between the dual metal sites reduces the *OH reduction energy barrier during the oxygen reduction pathway.
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ACS Nano
·
2019
·
IF 13.903
Shuang-Shuang Wan,Qian Cheng,Xuan Zeng,Xian-Zheng Zhang
Here, a Mn(III)-sealed metal–organic framework (MOF) nanosystem based on coordination between Mn(III) and porphyrin (TCPP) via a one-pot method was designed and constructed. Mn(III), as a sealer, not only quenched TCPP-based fluorescence but also inhibited reactive oxygen species (ROS) generation, which made MOFs an “inert” theranostic nanoparticle. Interestingly, upon endocytosis by tumor cells, MOFs were disintegrated into Mn(II) and free TCPP by intracellular glutathione (GSH) in tumor cells, owing to redox reaction between Mn(III) and GSH. This disintegration would lead to consumption of antioxidant GSH and activated Mn(II)-based magnetic resonance imaging (MRI) as well as TCPP-based fluorescent imaging. More importantly, such a GSH-regulated TCPP release could implement controllable ROS generation under irradiation, which avoided side effects (inflammation and damage of normal tissues). As a consequence, after unlocking by GSH, Mn(III)-sealed MOFs could significantly improve the therapeutic efficiency of photodynamic therapy by combining controlled ROS generation and GSH depletion after precise dual tumor homing.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2018
·Vol. 25
·期 23
·22818-22828
·
IF 2.8
Sun Yanlong,Zheng Tong,Zhang Guangshan,Liu Bei,Wang Peng
The regeneration of adsorbent by thermal method may transfer the adsorbed organic pollutants into the air phase. Herein, manganese and cerium are loaded on adsorbent as catalyst to mineralize the adsorbed organic pollutants during regeneration. The modified adsorbent is characterized by scanning electron microscope-energy dispersive spectrometer, Brunauer Emmett Teller-Barrett Joyner Halenda, and X-ray photoelectron spectroscopy. Regeneration of modified adsorbent is evaluated by adsorbent yield and mineralization percentage of the absorbed organic pollutants. The results demonstrate that the mineralization percentage of tetracycline increased about 100% after the modification. Besides, the loaded catalyst can significantly reduce the regeneration temperature. Furthermore, cerium can reduce the adverse impact causes by manganese which will decrease the adsorption capacity of adsorbent. Kinetics, equilibrium, thermodynamic, and other adsorption properties of modified adsorbent towards tetracycline are further studied. The theoretical maximum of adsorption capacity calculated by Langmuir model is 196.4 mg g −1 , and the kinetics of adsorption fits pseudo-second-order model. The adsorption of tetracycline on the adsorbent is feasible, spontaneous, and endothermic. The properties of synthesized composite material are stable; the yield of Ce/Mn/Al 2 O 3 adsorbent can keep higher than 95% even after five adsorption/regeneration cycles. This research provides another perspective on the design and regeneration of adsorbent, which focus on reducing the secondary pollution during adsorbent regeneration process.
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2015
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IF 2.729
Xiuli Song,Tailai Yang,Haiyan Du,Wenyan Dong,Zhenhai Liang
Transition metal mixed oxides of Mn and Cr with the nominal compositional formula Mn x Cr 1 − x O 1.5 ( x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were obtained by the thermal decomposition method. The powders were analyzed by SEM (scanning electron microscopy), XRD (X-ray diffraction) and XPS (X-ray photoelectron spectroscopy). The electrochemical properties of the Mn x Cr 1 − x O 1.5 electrodes for the OER (oxygen evolution reaction) in alkaline solution were evaluated by LSV (linear sweep voltammetry), staircase voltammetry and chronoamperometry . The results indicated that the mixed oxides were solid solutions of Mn 2 O 3 (bixbyite) and Cr 2 O 3 (eskolaite), and when x = 0.2, the catalyst had better catalytic activity in the OER process than did that of single Mn 2 O 3 and Cr 2 O 3 . At the high potential region (1.0 V vs Ag/AgCl), the current density of the Mn 0.2 Cr 0.8 O 1.5 electrode was ~ 80 times higher than that of Mn 2 O 3 and ~ 9 times higher than Cr 2 O 3 , and its overpotential ( η = 367.3 mV at a current density of 1.0 mA·cm − 2 ) was considerably lower than that of single Mn 2 O 3 ( η = 996.5 mV) and Cr 2 O 3 ( η = 648.5 mV) catalysts and was comparable to the precious metal oxide IrO x . The stability testing indicated that the mixed oxides had good stabilities in strong alkaline solution during the OER process.
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
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2014
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IF 2.129
Fang fei Liu,Ying Yu,Bi xia Lin,Xiao gang Hu,Yu juan Cao,Jian zhong Wu
Daminozide (B9) is a growth inhibitor with important regulatory roles in plant growth and development. Locating and quantifying B9-binding proteins in plant tissues will assist in investigating the mechanism behind the signal transduction of B9. In this study, red fluorescent Mn-doped CdTe quantum dots (CdTeMn QDs) were synthesized by a high-temperature hydrothermal process. Since CdTeMn QDs possess a maximum fluorescence emission peak at 610 nm, their fluorescence properties are more stable than those of CdTe QDs. A B9-CdTeMn probe was synthesized by coupling B9 with CdTeMn QDs. The fluorescence intensity of the probe is double that of CdTeMn QDs; its fluorescence stability is also superior under different ambient conditions. The probe retains the biological activity of B9 and is unaffected by interference from the green fluorescent protein present in plants. Therefore, we used this probe to label B9-binding proteins selectively in root tissue sections of mung bean seedlings. These proteins were observed predominantly on the surfaces of the cell membranes of the cortex and epidermal parenchyma.
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Journal of Materials Chemistry A
·
2017
·Vol. 5
·期 39
·20922-20931
·
IF 8.867
Jieyu Liu,Meng Yu,Xuewei Wang,Jie Wu,Changhong Wang,Lijun Zheng,Dachi Yang,Hui Liu,Yan Yao,Feng Lu,Weichao Wang
An alternative material SmMn2O5 mullite with regard to Pt/C is proposed to catalyze the oxygen reduction reaction (ORR) by combining density functional theory (DFT) calculations and experimental validations. Theoretical calculations are performed to investigate the bulk phase diagram, as well as the stability and electrocatalytic activity of the ORR under alkaline conditions for SmMn2O5 (001) surfaces, which are passivated by nitrogen atoms to avoid any spurious interference. The adsorptions of relevant ORR species (O*, OH*, OOH* and OO*) tend to compensate the coordination of manganese atoms to form Mn-centered octahedral or pyramidal crystal fields, and the corresponding binding energies fulfill a linear relationship. An oxygen molecule prefers to be reduced to OH−via a four-electron pathway and this prediction is verified by electrochemical measurements on the as-prepared SmMn2O5 catalyst with a nanorod structure. Volcano curves are obtained to describe the trends in theoretical ORR activity as a function of a single parameter, i.e. the oxygen binding energy. An overpotential of 0.43 V is obtained at the O* binding energy around 3.4 eV, which is close to the experimental observation (0.413 V) in this work. SmMn2O5 mullite exhibits favorable ORR activity and superior stability with only ∼5% decay in activity over 20 000 s of chronoamperometric operation in contrast to ∼15% decrease of Pt/C, making it a promising candidate for a cathode catalyst.
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JOURNAL OF ADVANCED OXIDATION TECHNOLOGIES
·
2016
·Vol. 19
·期 2
·358-365
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IF 0.738
Yanfang Liu,Guixia Li,Zhili Zhang,Xiang Gao,Jianrui Niu,Junna Zhao,Zaixing Li
γ-Al 2 O 3 supported Manganese and Ferric oxide (Mn-Fe/Al 2 O 3 ) were synthesized and used as catalyst for ozonation of bisphenol A (BPA) in aqueous solution. It was conducted in a semi-batch reactor under different operational conditions, i.e., varying initial pH, ozone flow rate, initial BPA concentration and catalyst dosage. The results indicated that the presence of Mn-Fe/Al 2 O 3 lead to a great enhancement in ozonation of BPA. Using 5 g/L Mn-Fe/Al 2 O 3 evaluated BPA (50 mg/L) removal efficiency up to 84.1% under particular reaction conditions, while that of the single ozonation process was 48.5%. The influence of tert-butanol demonstrated that initiation of hydroxyl radicals was involved and plays an important role in catalytic ozonation. The decrement of solution pH in catalytic ozonation was much higher than that in ozone alone, indicating much small molecule acids produced in catalytic ozonation process. The repeated use the Mn-Fe/Al 2 O 3 proved that it had a good reusability and stability.
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Scientific Reports
·
2016
·Vol. 6
·期 1
·1-8
·
IF 5.228
Cai Kedi,Yang Rui,Lang Xiaoshi,Zhang Qingguo,Wang Zhenhua,He Tieshi
Gradient Mn-La-Pt catalysts with three-layered structure of manganese dioxide (MnO 2 ), lanthanum oxide (La 2 O 3 ), and Platinum (Pt) for Li-O 2 battery are prepared in this study. The mass ratio of the catalysts is respectively 5:2:3, 4:2:4, and 3:2:5 (MnO 2 : La 2 O 3 : Pt) which is start from the side of the electrolyte. The relationship between morphology structure and electrochemical performance of gradient catalyst is investigated by energy dispersive spectrometry and constant current charge/discharge test. The Li-O 2 battery based on gradient Mn-La-Pt catalysts shows high discharge specific capacity (2707 mAh g −1 ), specific energy density (8400 Wh kg −1 ) and long cycle life (56 cycles). The improvement of the Li-O 2 battery discharge capacity is attributed to the gradient distribution of MnO 2 and Pt and the involvement of La 2 O 3 that can improve the energy density of the battery. More important, this work will also provide new ideas and methods for the research of other metal-air battery.
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ACS Applied Materials & Interfaces
·
2025
·
IF 8.2
Yifeng Xia,Hua Hao,Cheng Tao,Minghe Cao,Zhonghua Yao,Hanxing Liu
Dielectric capacitors are essential in advanced electronics and power systems due to their high power density and fast charge–discharge rates. However, their application is limited by their low energy storage density and efficiency. Aurivillius-phase ferroelectrics have shown promise as energy storage materials, but their low polarization and significant hysteresis remain critical challenges. In this study, we present a simple and cost-effective defect-engineering strategy to enhance the energy storage performance of SrBi5Ti4FeO18 thin film through Mn doping. Mn incorporation suppresses oxygen vacancy formation and induces tensile chemical stress in the lattice, which simultaneously enhances maximum polarization and reduces the hysteresis. Additionally, the reduction in oxygen vacancies promotes grain refinement, reduces leakage current, and significantly enhances the breakdown strength. The optimized SrBi5Ti3.91Mn0.09FeO18 thin film achieves an ultrahigh energy storage density of 105 J/cm3 with improved efficiency of 70% at 3569 kV/cm. Moreover, it demonstrates good frequency stability (100 Hz to 10 kHz), thermal stability (20–160 °C), and fatigue endurance over 105 cycles. This work provides a feasible method for developing advanced dielectric capacitors with high energy storage performance by the rational design and precise control of defects.
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JOURNAL OF MATERIALS SCIENCE
·
2017
·Vol. 53
·期 2
·1286-1296
·
IF 2.599
Cao Sheng,Zheng Jinju,Dai Chencheng,Wang Lin,Li Chengming,Yang Weiyou,Shang Minghui
In this report, doping concentration-dependent photoluminescence (PL) properties of Mn-doped ternary Zn–In–S quantum dots (QDs) were studied by using steady-state and time-resolved PL spectroscopy. The QDs PL was firstly significantly intensified with the increasing Mn doping concentration and then decreased after the doping concentration increased up to 7.5 at.%. However, their decay lifetimes exhibit a monotone decrease with Mn doping concentration ranged from 0 to 10 at.%. It can be concluded that the PL intensity was mainly determined by two factors: one was the increased efficiency of energy transfer from host excitons to Mn 2+ ion accepter, and the other was the decreased efficiency of the emission from a Mn 2+ ion, which was caused by the increased component of exposed Mn 2+ ions on QDs surface and the accelerated interaction between adjacent dopants. The competition of above two exciton relaxation dynamics processes determined the trend of the PL intensity, while the latter was responsible for the monotonously decreased lifetime of the Mn 2+ ion emission with the increasing Mn doping concentration.
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Small
·
2024
·
IF 13
Lili Xu,Jianli Nan,Songxue Han,Zhixuan Yu,Shuangli Wu,Youxing Fang,Shaojun Dong
In nature, active Mn 3+ –ligand complexes produced by laccase catalyzed oxidation can act as the low-molecular mass, diffusible redox mediators to oxidize the phenolic substrates overcoming the limitations of natural enzymes. Learning from the metal–ligand coordination of natural functional units, high-valence Mn metal–organic framework (Mn MOF) is constructed to simulate the catalysis in natural mediator system. Benefiting from the characteristics of nanoscale size, rich metal coordination unsaturated sites, and mixed valence state dominated by Mn(III), Nano Mn(III)-TP exhibits superior laccase-mimicking activity, whose V max (maximal reaction rate) is much higher than that of natural laccase. Referring to natural systems, relevant free radical experiments prove that the material induces the production of active oxygen species with the assistance of carboxylic acid, and active oxygen species further oxidize phenolic substrates. Based on its robust performances, the primary oxidative degradation of an emerging pollutant triclosan (TCS) is creatively applied, an important antiasthmatic medicine terbutaline sulfate (TBT) detection, and the synthesis of non-toxic and black near-natural dyes for dyeing. By simulating the essential mediators of natural enzymatic catalysis, an Mn MOF-based material that demonstrates multiple novel applications is successfully developed, which introduces a new reliable strategy for achieving versatile nature-mimicking catalysis.
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Biomedical Materials
·
2024
·Vol. 19
·期 6
·065025
·
IF 3.9
Xiaohuan Guo,Qi Fang,Nan Leng,Yuan Liu,Bingbing Cai,Yuzhu Zhou,Changchun Wen
Chemodynamic therapy (CDT) is a new method for cancer treatment that produces highly toxic reactive oxygen species (ROS) in the tumor microenvironment to induce cancer cell apoptosis or necrosis. However, the therapeutic effect of CDT is often hindered by intracellular H2O2 deficiency and the activity of antioxidants such as glutathione (GSH). In this study, a nano-catalyst HCM was developed using a self-assembled Cu/Mn-doped metal-organic framework, and its surface was modified with hyaluronic acid to construct a tumor-targeting CDT therapeutic agent with improved the efficiency and specificity. Three substances HHTP (2, 3, 6, 7, 10, 11-hexahydroxybenzophenanthrene), Cu2+, and Mn2+ were shown to be decomposed and released under weakly acidic conditions in tumor cells. HHTP produces exogenous H2O2 in the presence of oxygen to increase the H2O2 content in tumors, Cu2+ reduces GSH content and generates Cu+ in the tumor, and Cu+ and Mn2+ catalyze H2O2 to produce OH in a Fenton-like reaction. Together, these three factors change the tumor microenvironment and improve the efficiency of ROS production. HCM showed selective and efficient cytotoxicity to cancer cells, and could effectively inhibit tumor growth in vivo, indicating a good CDT effect.
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