ENVIRONMENTAL POLLUTION
·
2024
·
IF 7.6
Ruihan Xiong,Caixiang Zhang,Hanxiang Xiong,Shuxin Huang,Jiasen Li
Glyphosate as an effective broad-spectrum herbicide is frequently detected in various water and soil resources. Given the ubiquity of β-MnO 2 and δ-MnO 2 colloids in groundwater and soil, the abiotic removal of glyphosate by MnO 2 colloids was investigated. β-MnO 2 colloids exhibited superior glyphosate removal efficiency, up to 37%, compared to 21% for δ-MnO 2 colloids at a pH of 4.0. Glyphosate removal involved simultaneous adsorption and oxidation process , identified by HRTEM , NH 3 -TPD, XPS , LC-MS, FTIR analyses and the occurrence of aminomethylphosphonic acid (AMPA) and Mn 2+ . Moreover, adsorption dominated the removal of glyphosate by two MnO 2 colloids. The solution pH had a substantial effect on glyphosate removal. Co-existing ions in the solution, such as carbonate (CO 3 2− ), phosphate (Na 2 HPO 4 , NaH 2 PO 4 ) and humic acid (HA), were also found to impede glyphosate removal. Phosphate, in particular, exhibited a strong competitive effect for adsorption sites on both MnO 2 colloids. Of them, the removal of glyphosate by β-MnO 2 colloids was more prone to occur due to its higher specific surface area , abundant oxygen vacancies , and moderate acid sites. However, δ-MnO 2 colloids presented a stronger oxidation capacity than that of β-MnO 2 colloids due to the quicker generation rate of Mn 2+ . Finally, AMPA was the same products by two MnO 2 colloids in the oxidation process, revealing the degradation pathway based on the cleavage of C–N bond. Therefore, by comparing kinetics and mechanisms of glyphosate removal by β- and δ-MnO 2 colloids, this study improves us better understanding for the behavior of glyphosate in the environment.
研究领域:
环境科学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Nanoscale Research Letters
·
2015
·Vol. 10
·期 1
·1-9
·
IF 2.779
Zhang Li,Jamal Ruxangul,Zhao Qin,Wang Minchao,Abdiryim Tursun
The nanocomposite materials of poly(3,4-ethylenedioxythiophene)/graphene oxide (PEDOT/GO), poly(3,4-ethylenedioxythiophene)/MnO 2 (PEDOT/MnO 2 ), and poly(3, 4-ethylenedioxythiophene)/graphene oxide/MnO 2 (PEDOT/GO/MnO 2 ) were successfully prepared by facile and template-free solution method. The structure and morphology of nanonanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible absorption spectra (UV–vis), field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX), respectively. The catalytic activities of nanocomposites were investigated through the degradation processes of methylene blue (MB) solution under dark, UV light, and nature sunlight irradiation, respectively. The results displayed that nanocomposites were successfully synthesized, and PEDOT/GO had higher conjugation length and doped degree than pure PEDOT. However, the introduction of MnO 2 could lead to the reduction of conjugation length and doped degree in PEDOT/MnO 2 and PEDOT/GO/MnO 2 nanocomposites. The field emission scanning electron microscope (FESEM) analysis also showed that both MnO 2 and GO had some effect on the morphology of nanocomposites. The catalytic activities of pure PEDOT and nanocomposites were in the order of PEDOT/GO/MnO 2 > PEDOT/MnO 2 > PEDOT/GO > pure PEDOT. Besides, the catalytic results also showed that the highest degradation efficiency of MB after 7 h occurred in the PEDOT/GO/MnO 2 composite in three irradiation.
研究领域:
材料化学
·
环境催化
·
纳米材料科学
·
高分子化学
·
光催化
✓ 已验证
DOI
高影响因子
Crystals
·
2022
·Vol. 12
·期 11
·1600
·
IF 2.67
Kun You,Yifei Yuan,Xiuxian Liao,Wenjun Song,Xuedong He,Huile Jin,Shun Wang
Manganese dioxide is regarded as a promising energy functional material due to its open tunnel structure with enormous applications in energy storage and catalysis. In this paper, α-MnO2with a 2 × 2 tunnel structure and β-MnO2with a 1 × 1 tunnel structure were hydrothermally synthesized, which possess characteristic tunnel structures formed by the interconnected unit structure of [MnO6] octahedrons. With regards to their different tunnel dimensions, the specific mechanism of ion intercalation in these two phases and the effect on their performance as aqueous Zn-MnO2battery cathodes are explored and compared. Comprehensive analyses illustrate that both α-MnO2and β-MnO2provide decent capacity in the aqueous battery system, but their intrinsic stability is poor due to the structural instability upon cycling. At the same time, experiments show that α-MnO2has a better rate performance than β-MnO2under larger currents, thus implying that the former has a broader application in this aqueous battery system.Keywords:α-MnO2and β-MnO2nanostructures;aqueous zinc batteries;electrochemical characterization
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
ELECTROCHIMICA ACTA
·
2020
·
IF 6.215
Ce Qiu,Xiaohui Zhu,Liang Xue,Mingzhu Ni,Yang Zhao,Bo Liu,Hui Xia
Adding Mn 2+ in aqueous electrolyte is a well adopted approach to improve cycle performance for Zn/MnO 2 batteries. The function of Mn 2+ additive in aqueous electrolyte, however, is not well understood, which could affect revealing the real performance of the MnO 2 cathode itself. In this work, a battery system with Zn anode and birnessite MnO 2 cathode is constructed and systematically investigated by using MnSO 4 additive in the electrolyte with different concentrations. The function of Mn 2+ in the electrolyte, the structural evolution of the electrode, the reaction mechanism, and the cause for capacity fading are comprehensively investigated in this system. It is found that Mn 2+ can be continuously electro-oxidized at the cathode and form ε-MnO 2 when the charge voltage is above 1.7 V during cycling, leading to successive capacity increase up to hundreds of cycles. The capacity increase, however, stops after certain cycle numbers, and is followed by fast capacity fading, which is correlated to the competition between ε-MnO 2 formation and phase transition from birnessite to spinel ZnMn 2 O 4 . It is suggested that addition of Mn 2+ in the electrolyte cannot stabilize the MnO 2 cathode and the improved cycle performance is achieved at the expense of consuming the Mn 2+ in the electrolyte.
研究领域:
电化学
·
材料科学
✓ 已验证
DOI
高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2022
·Vol. 29
·期 29
·44732-44745
·
IF 5.19
Wang Zhijie,Bao Jianguo,Du Jiangkun,Luo Liting,Xiao Guangfeng,Zhou Ting
Pollutant degradation via periodate ( \({\text{IO}}_{4}^{-}\) ) and transitional metal oxides provides an economical, energy-efficient way for chemical oxidation process in environmental remediation. However, catalytic activation of periodate by manganese dioxide and the associated mechanism were barely investigated. In this study, four MnO 2 polymorphs (α-, β-, γ- and δ-MnO 2 ) were synthesized and tested to activate \({\text{IO}}_{4}^{-}\) for the degradation of sulfamethoxazole (SMX). The reactivity of different MnO 2 structures followed the order of α-MnO 2 > β-MnO 2 > γ-MnO 2 > δ-MnO 2 , suggesting that the particular crystalline structure in α-MnO 2 would exhibit higher activities via \({\text{IO}}_{4}^{-}\) activation. Herein, in α-MnO 2 / \({\text{IO}}_{4}^{-}\) system, 91.1% of SMX was eliminated within 30 min with degradation rate constant of 0.0649 min −1 , and the neutral pH exhibited higher efficiency in SMX degradation compared with acidic and alkaline conditions. Singlet oxygen ( 1 O 2 ) was unveiled to be the dominant ROS according to the results of electron paramagnetic resonance, chemical probes and radical quenching experiments, whereas \({\mathrm{O}}_{2}^{\bullet -}\) and • OH were mainly acted as a free-radical precursor. Six oxidation products were identified by LC–MS, and the elimination of sulfonamide bond, hydroxylation and direct oxidation were found to be the important oxidation pathways. The study dedicates to the mechanistic study into periodate activation over alpha-MnO 2 and provides a novel catalytic activation for selective removal in aqueous contaminants.
研究领域:
环境科学
·
化学工程
·
污染控制
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Crystals
·
2020
·Vol. 10
·期 8
·705
·
IF 2.404
Yunfeng Deng,Junjun Wang,Chunxiao Zhang,Hui Ma,Chungeng Bai,Danqing Liu,Fengmin Wu,Bin Yang
Structural, ferroelectric, dielectric, and piezoelectric properties of K0.5Na0.5NbO3-LiTaO3-xmol%MnO2lead-free piezoelectric ceramics with 0.0 ≤x≤ 0.3 were studied. The ceramic samples were synthesized through the conventional solid-state reaction method. The MnO2addition can reduce the sintering temperature of KNLNT ceramics. Compared with undoped KNLNT ceramic, the piezoelectric measurements showed that piezoelectric properties of K0.5Na0.5NbO3-LiTaO3-xMnO2were improved (d33= 251 pC/N) whenx= 0.1. In addition, KNLNT-xMnO2ceramics have largerPr(20.59~21.97 μC/cm2) and smallerEc(10.77~6.95 kV/cm), which indicates MnO2has excellent softening property, which improves the ferroelectric properties of KNLNT ceramics This work adds relevant information regarding of potassium sodium niobate K0.5Na0.5NbO3(KNN) when doped Li, Ta, Mn at the B-site.Keywords:KNLNT ceramics;MnO2doped;ferroelectricity;piezoelectricity
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
ChemistrySelect
·
2024
·Vol. 9
·期 6
·e202304564
·
IF 1.9
Ke Li,Zhifang Li,Jinxing Cui,Boyang Zhou,Weiwei Dong,Boxuan Zhang,Changlong Yang
Graphical PANI/FeS 2 /MnO 2 composite electrode materials were successfully prepared. The results showed that the specific capacitance of PANI/FeS 2 /MnO 2 4 : 1 : 3 was 580 F/g at 1 A/g, and the capacitance retention rate was 85.2 % after cycling 10,000 times at 5 A/g. The asymmetric supercapacitor PANI/FeS 2 /MnO 2 4 : 1 : 3 //AC had an energy density of 37.93 Wh/kg at a power density of 0.85 kW/kg. Polyaniline (PANI) has unique physical and chemical peculiarities, so it has been widely researched in the field of energy storage. However, its structure is easy to be damaged during charging and discharging, which seriously affects its application. PANI/FeS 2 /MnO 2 composite materials were successfully prepared by an easy combination of chemical precipitation and chemical oxidative polymerization. The electrochemical test results manifested that the specific capacitance of PANI/FeS 2 /MnO 2 4 : 1 : 3 was 580 F/g at 1 A/g, and had great cyclic stability (capacitance retention rate was 85.2 % after 10000 cycles at 5 A/g). It was because that reticular structure shortened the ion transport path. On the other hand, it was able to effectively mitigate the volume change during long-term charging and discharging, thus improving the cycling stability. In addition, PANI/FeS 2 /MnO 2 4 : 1 : 3 as the positive and activated carbon (AC) as the negative, an asymmetrical supercapacitor was assembled with a maximal energy density of 37.93 Wh/kg when its power density was 0.85 kW/kg. At the same time, the device possessed a long cycle life (the capacitance conservation rate was 82 % after 5000 cycles at 5 A/g). This excellent performance is due to the excellent synergy between the PANI, FeS 2 and MnO 2 . This study opens a new way to investigate polyaniline-based composite electrode materials.
研究领域:
材料科学
·
能源存储
✓ 已验证
产品关联
DOI
高影响因子
AIP Advances
·
2024
·Vol. 14
·期 3
·
IF 1.4
Wang Xingtian,Zhu Junfeng,Liu Wenbing,Li Wei,Wang Hu
High levels of groundwater containing both arsenic and fluorine are prevalent, resulting in serious health problems when consumed as drinking water. This co-pollution phenomenon is widespread and requires urgent attention. The multiple forms of arsenic and arsenic–fluorine co-contamination pose a significant challenge to efficiently co-remove both substances. This research utilized a green and stable synthesis approach to create MgLaFe layered double oxide (LDO) heterostructures, which were anchored on α-MnO 2 nanowires. The materials comprise magnesium and lanthanum elements with a powerful attraction toward fluoride ions; elemental iron, which can establish stable compounds with arsenate; and MnO 2 , which can effectively oxidize arsenous acid, thereby enabling efficient co-removal of arsenic and fluorine. The efficient oxidation process of the MnO 2 nanowire and the prompt ion adsorption process of the LDO work together synergistically. The adsorption performance was assessed through isotherms and kinetic fitting. Chemisorption was found to be the process for As(Ⅲ), As(V), and F − adsorption, with As(Ⅲ) going through monolayer adsorption on the surface of MnO 2 nanowires, while As(V) and F − were mainly adsorbed by multilayer process on LDO. The maximum adsorption capacities were 111.76, 230.51, and 765.10 mg/g for As(Ⅲ), As(V), and F − , respectively. The x-ray photo-electronic spectroscopy analysis provided further elucidation on the adsorption mechanism of the MnO 2 @LDO heterostructure, detailing each component's role in the process. The results confirm the successful construction of the heterostructure and the efficient coupling of oxidation and adsorption.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2024
·
IF 8.3
Xiaotian Xie,Yi Xu,Jie Liu,Dongtian Wang,Tingting Lv,Fanshu Yuan,Qianli Zhang
Structural regulation is an effective strategy for enhancing an electrode's energy storage performance. Herein, lignin-derived carbon dots (LCDs) are explored for the structural tailoring of NiSe/MnO2 to improve the electrochemical performance in supercapacitors. After the dendritic NiSe microcrystals are synthesized via a microwave method, NF/NiSe/MnO2-LCDs are prepared by another microwave process to form a composite mixture of LCDs, MnO2, and NF/NiSe. At 1 A g–1, NF/NiSe/MnO2-LCDs possess a specific capacitance of 2268 F g–1 and superb lifespans (84.43%, 3000 cycles) for their enhanced ion transport and rapid electron transfer. In addition, the NF/NiSe/MnO2-LCDs//AC ASC showed an energy density of 51.62 Wh kg–1 at 800 W kg–1 and extraordinary endurance with 88.46% retention (7000 loops). The NF/NiSe/MnO2-LCDs offer ideas to improve the capacity retention and storage capacity of electrodes for supercapacitors.
研究领域:
材料科学
·
能源存储
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2020
·Vol. 31
·期 12
·9352-9365
·
IF 2.22
Li Cai-Xia,Yang Bin,Zhang Shan-Tao,Hong Yue-Nan,Liu Dan-Qing,Zhang Rui,Shuo Gu,Cao Wen-Wu
Lead-free Ba 0.70 Ca 0.30 TiO 3 + x mol% MnO 2 (abbreviated as BCTM x , x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 1.0 and 1.2) piezoelectric ceramics were synthesized by the solid-state reaction method. The effects of MnO 2 additives on the phase transition, microstructure, dielectric, ferroelectric, strain behaviors and piezoelectric properties are investigated. BCTM x ceramics ( x = 0–1.2) exhibit diphasic tetragonal and orthorhombic phases. The tetragonal phase is gradually suppressed by increasing x . As x increases from 0 to 1.2, the Curie temperature ( T C ) decreases monotonically from 128 to 45 °C, while the grain size, dielectric and ferroelectric properties increase and reach the maximum near x = 0.6. On the other hand, the piezoelectric coefficient ( d 33 ) and the electromechanical coupling coefficient ( k p %) decrease simultaneously, whereas the mechanical quality factor ( Q m ), bipolar and unipolar strain increase and reach the maximum values of 684, 0.28% and 0.24%, respectively, near x = 0.6. The optimum electrical performance with \(\varepsilon_{r}\) = 1323, tan \(\delta\) = 0.08, T C = 66 °C, P max = 12.2 μC/cm 2 , P r = 6.9 μC/cm 2 , E C = 13.3 kV/cm, d 33 = 116 pC/N, k p % = 0.22%, Q m = 684 and the normalized strain \(d_{33}^{*}\) = S max / E max as high as 480 pm/V were observed for x = 0.6. The high strain and Q m suggested that the MnO 2 -modified Ba 0.70 Ca 0.30 TiO 3 ceramics are promising candidate for high power applications.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
Molecular Catalysis
·
2023
·
IF 4.6
Xi Zhang,Lingling Ren,Liang Sun,Zhuobin Huo,Bangjie Tan,Nengjie Feng,Hui Wan,Guofeng Guan
Manganese oxides were received extensive attention on account of its low cost, variable valence state and excellent redox properties. Herein, we successfully prepared various Fe-doped MnO 2 catalysts to further improve the catalytic activity of MnO 2 on propane. Physicochemical characterization results displayed that with the increase of Fe doping amounts, the crystalline phase of MnO 2 gradually changed from α-MnO 2 and β-MnO 2 to Fe 2 O 3 , the particle size of catalysts decreased and the specific surface area increased. However, increasing the content of Fe could not monotonically enhance the catalytic performance of catalysts on propane. When the molar ratio of Fe/Mn was 0.25, the largest amount of Mn 4+ species and lattice oxygen species were exposed on the surface of Mn8Fe2, and showed the best low temperature reducibility , which was ascribed to the synergistic effect between Mn and Fe was enhanced. It presented optimal catalytic activity for propane oxidation with temperature of propane conversion at 90% (T 90 ) as low as 279 °C under 0.1% propane and 5% O 2 . This work provided a new way to design and synthesize efficient non-noble metal catalysts for the elimination of propane, which had certain application value.
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
JOURNAL OF THE BRAZILIAN CHEMICAL SOCIETY
·
2018
·Vol. 29
·期 2
·404-411
·
IF 1.444
Song Jia-Xing,Fang Xiang,Guo Tao,Bei Feng-Li,Ding Wen,Zhang Xiao-Nan,Yao Miao,Yu Hong-Jun
In this work, thermal properties and kinetics of Al-nanoparticles/α-MnO2 nanorods thermite were reported. The α-MnO2 nanorods were synthesized using a hydrothermal method and were characterized by X-ray powder diffraction (XRD) and X-ray photoelectron spectra (XPS), then combined with Al nanoparticles based on the ultrasonic mixing method to prepare the nanostructure thermite. Besides, both pure components and mixture were characterized by field emission scanning electron microscopy (FE-SEM) to observe their morphologies and structures. Subsequently, the thermal properties of Al/α-MnO2 nanostructure thermite were studied on the basis of thermogravimetric-differential scanning calorimetry (TG-DSC). According to the TG-DSC tests, the calculation results of activation energy for kinetics of Al/α-MnO2 thermite were obtained using different isoconversional methods. It was found that Al/α-MnO2 nanostructure thermite has high heat release and low onset temperature, and the heat release of the nanostructure thermite was approximately 1146.6 J g -1.
研究领域:
材料科学
·
热化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）