APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Wenyu Zhao,Qingquan Kong,Xiaoqiang Wu,Xuguang An,Jing Zhang,Xiaonan Liu,Weitang Yao
Aqueous zinc-ion batteries (ZIBs) are potential candidates for achieving considerable energy savings owing to their environmental benignity and low cost. At present, however, Mn 2+ dissolution causes structural failure in manganese-based cathodes. Therefore, addressing this issue is vital for improving their cycling stability and specific capacity. Herein, ε-MnO 2 was obtained by annealing MnCO 3 at 350 °C. Subsequently, ε-MnO 2 was coated with a carbon layer (carbonizing D-glucose) to obtain ε-MnO 2 @C, which effectively mitigated the Mn 2+ dissolution as well as the side reactions between the electrode and electrolyte. Electrochemical results revealed a significant improvement in the specific capacity (280 mAh g −1 at 0.2 A g −1 ) and capacity retention (∼91% over 1700 cycles at 1 A g −1 ) of the ε-MnO 2 @C cathode.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
Crystals
·
2023
·Vol. 13
·期 12
·1664
·
IF 2.7
Yulong Chen,Yuan Chi,Xiao Wu,Cong Lin,Tengfei Lin,Min Gao,Chunlin Zhao,Baisheng Sa
The widespread use of pharmaceuticals and personal care products (PPCPs) in many fields has brought convenience to human lives but has also caused unavoidable environmental pollution issues. In particular, the resistance gene problem resulting from accumulating antibiotics that cannot be fully absorbed by biological individuals has been a concern; thus, it is urgent to find efficient technologies to boost the degradation efficiency of antibiotics in the environment. Here, an ε-MnO2catalyst was prepared by a novel droplet-interface-drying method and utilized as a Fenton-like catalyst for efficiently degrading ciprofloxacin (CIP). The ε-MnO2shell was formed preferentially at the gas–liquid interface and then continued to decompose into ε-MnO2with abundant O vacancies in the air-insulated microcavity. The XPS result confirms that this particular preparation method can regulate the content of O vacancies in the material. Compared with ε-MnO2samples obtained by the direct drying method (ε-MnO2-B), the catalytic performance of ε-MnO2prepared by the droplet-interface-drying method (ε-MnO2-P) is significantly improved. By activating peroxymonosulfate (PMS) with the ε-MnO2-P catalyst, the CIP degradation efficiency can reach 84.1%. The detection and analysis of reactive oxygen species (ROS) in the ε-MnO2-P/PMS oxidation system confirms that ·OH, SO4·−and1O2are the main ROS for CIP degradation. This study highlights the creation of miniature hypoxic space to regulate the content of O vacancies in ε-MnO2, providing a new idea for the synthesis of other O-vacancy-rich materials.Keywords:droplet-interface-drying method;Fenton-like oxidation;ε-MnO2;ciprofloxacin;water purification
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
Journal of Cleaner Production
·
2024
·
IF 9.7
Yuebei Yang,Yaozhong Wang,Chao Xue,Yujung Lin,Jyh-Fu Lee,Xiaoyun Yi,Zhi Dang
The clean-up of acid mine drainage (AMD) is challenging, as classical treatment including a pH neutralization step produces large amounts of toxic sludge . Here we demonstrated that removal of heavy metals through adsorption at low pH was achievable with the use of ε-MnO 2 adsorbent, which could be produced in a simple one-step process. The material, which was negatively charged even at pH 2, exhibited outstanding potential for the removal of heavy metals at strongly acidic pH. At pH 2, adsorption capacities were achieved of 172.14 mg/g towards Pb 2+ (at an initial concentration of 400 mg/L), 65.64 mg/g for Fe 3+ (at 300 mg/L) and 8.5 mg/g for Cd 2+ (at 10 mg/L). Mechanistic studies revealed that ion exchange was the main adsorption mechanism for removal of Pb 2+ , while electrostatic interaction was dominant for Fe 3+ and Cd 2+ removal. In the case of Pb 2+ adsorption, double corner sharing (DCS) complexes were formed at the edges, which promoted the dissolution of structural Mn(III), thereby generating Mn 2+ and vacancies which promoted Pb 2+ adsorption via an ion exchange process. In the case of Fe 3+ and Cd 2+ adsorption, along with electrostatic adsorption, triangle corner sharing (TCS) dominated complex formation at the intermediate vacancies, and less Mn 2+ was released. Note that the Mn 2+ was in dynamic equilibrium with structural Mn(Ⅲ) and Mn(Ⅳ). The actual AMD was retreated in 5 cycles by ε-MnO 2 , the removal rates of 100% were achieved for Pb 2+ , Fe (total) and Mn 2+ , together with 98% for Cu 2+ and 95.1% for Cd 2+ , all of which reached the national emission standards. This approach is a highly suitable option for AMD treatment that avoids toxic sludge formation.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
ENVIRONMENTAL POLLUTION
·
2022
·
IF 9.988
Yuebei Yang,Yaozhong Wang,Xiaofei Li,Chao Xue,Zhi Dang,Lijuan Zhang,Xiaoyun Yi
The heavy-metal adsorbent ε-MnO 2 was produced through a simple, one-step oxidation-reduction reaction at three different synthesis temperatures (25 °C, 50 °C and 75 °C) and their morphology and chemical-physical properties were compared. Of the three materials, MnO 2 -25 had the largest specific surface area and the highest surface hydroxyl concentration. Its optimal performance was demonstrated by batch adsorption experiments with Pb 2+ , Cd 2+ and Cu 2+ . Of the three metals, Pb 2+ was adsorbed best (339.15 mg/g), followed by Cd 2+ (107.50 mg/g) and Cu 2+ (86.30 mg/g). When all three metals were present, Pb 2+ was still absorbed best but now more Cu 2+ was adsorbed than Cd 2+ . In order to explore the mechanism for the inconsistent adsorption order of Cd 2+ and Cu 2+ in single and competitive adsorption, we combined experimental data with density functional theory (DFT) calculations to elucidate the distinct adsorption nature of MnO 2 -25 towards these three metals. This revealed that the adsorption affinity of the (100) facet was superior to (001), and since the surface complexes were also more stable on (100), this facet was most likely determining the adsorption order for the single metals. When the metals were present in combination, Pb 2+ preferentially occupied the active adsorption sites of (100), forcing Cu 2+ to be adsorbed on the (001) facet where Cd 2+ was only poorly bound. Thus, the adsorption behavior was affected by MnO 2 -25 surface chemistry at a molecular scale. This study provides an in-depth understanding of the adsorption mechanisms of the heavy metals on this adsorbent and offers theoretical guidance for production of adsorbent with improved removal efficiency.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Materials Chemistry A
·
2015
·Vol. 3
·期 31
·16168-16176
·
IF 7.443
Hao Wang,Fengxiang Yin,Biaohua Chen,Guoru Li
An ε-MnO2/metal–organic-framework (Fe) (i.e., ε-MnO2/MOF(Fe)) composite was synthesised by integrating ε-MnO2 and a MOF(Fe) support. The composite was characterised using X-ray diffraction, N2 adsorption–desorption, field emission scanning electron microscopy, transmission electron microscopy, elemental mapping, Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The ORR activity of the composite was evaluated by cyclic and linear sweep voltammetries in an alkaline electrolyte. The results revealed that in the ε-MnO2/MOF(Fe) composite, ε-MnO2 is in the form of nanorods, each with one end protruding and the other firmly anchored on the MOF(Fe) matrix with a high porosity and a high specific surface area. This unique structure of the composite is advantageous for oxygen diffusion and contact with ε-MnO2 during reactions, resulting in much better ORR activity and stability than those of ε-MnO2 in an alkaline electrolyte. The ε-MnO2/MOF(Fe)-catalysed ORR favours an apparent 4-electron transfer pathway in which oxygen was first reduced to hydroperoxide, which was further chemically decomposed into primarily OH− and O2.
研究领域:
材料化学
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电化学
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纳米催化
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能源材料
·
无机功能材料
✓ 已验证
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
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2021
·
IF 8.128
Aimal Khan,Kaikai Zhang,A Taraqqi-A-Kamal,Xiaoguang Wang,Yong Chen,Yanrong Zhang
ε-MnO 2 effectively activates peroxymonosulfate (PMS) for the efficient degradation of emerging pollutants. ε-MnO 2 was synthesized by a facile thermal-treatment method and its long-term stability and efficiency for the elimination of emerging pollutants, including sulfamethoxazole (SMX), sulfachloropyridazine (SCP), sulfamethazine (SMT), ciprofloxacin (CIP), and azithromycin (AZI), from aqueous media were evaluated. ε-MnO 2 was found to activate PMS more efficiently than α-MnO 2 , β-MnO 2 , or δ-MnO 2 , owing to its high − OH-group content, unique structure, and high surface area. Sulfate (SO 4 •− ), hydroxyl (•OH), and superoxide (O 2 •− ) radicals, as well as singlet oxygen ( 1 O 2 ) were generated, with O 2 •− acting as the 1 O 2 precursor. The ε-MnO 2 /PMS system proved to be effective in the pH range of 3.5–9.0 and the rate of SMX degradation was not significantly affected by the presence of inorganic anions or natural organic matter. The proposed pathway for the activation of PMS by ε-MnO 2 includes inner-sphere interactions between ε-MnO 2 and PMS, and electron transfer to PMS via the MnIII ↔ MnIV redox cycle, which generates reactive oxygen species. These findings provide new insight into PMS activation by less-toxic metal oxides as catalysts and demonstrate that Mn-based materials can be used to effectively treat water matrices containing emerging pollutants.
研究领域:
环境科学
·
催化材料
✓ 已验证
DOI
PubMed
高影响因子
Catalysis Science & Technology
·
2025
·
IF 4.2
Yongle Zhang,Yingyi Tu,Yunying Huo,Guang Pan,Qiao Zhang,Zhiting Liu,Guangxing Yang,Feng Peng
The electrochemical catalytic oxidation of 5-hydroxymethylfurfural (HMF) to generate high-value products like 2,5-furandicarboxylic acid (FDCA) has become a prominent research interest. In this work, an economical and efficient transition metal ε-MnO2 catalyst was used to electrocatalyze the oxidation of HMF in acidic environments. The results revealed a highly efficient HMF conversion rate of 92.95% and a FDCA yield of 23.03% under the specific conditions of 60 °C, 0.5 M H2SO4 and 1.6 V (vs. RHE). Furthermore, the study outlined the oxidation pathway for HMF, which progresses through the following sequence: HMF → DFF → FFCA → FDCA. The apparent activation energies associated with each oxidation stage were found to be 25.52, 22.12 and 16.21 kJ mol−1, respectively. Moreover, the findings indicated a favorable relationship between the electrocatalytic oxidation activity of HMF and the average surface oxidation state of ε-MnO2.
研究领域:
化学
·
材料科学
·
催化反应
✓ 已验证
产品关联
DOI
高影响因子
INORGANIC CHEMISTRY
·
2024
·
IF 4.3
Fu Wan,Ruiqi Liu,Yaoyang Xia,Kaida Hu,Yu Lei,Changding Wang,Sida Zhang,Shufan Li,Da Yang,Yujie Zheng,Weigen Chen
Rechargeable Zn-MnO2 batteries using mild water electrolytes have garnered significant interest owing to their impressive theoretical energy density and eco-friendly characteristics. However, MnO2 suffers from huge structural changes during the cycles, resulting in very poor stability at high charge–discharge depths. Briefly, the above problems are caused by slow kinetic processes and the dissolution of Mn atoms in the cycles. In this paper, a 2D homojunction electrode material (δ/ε-MnO2) based on δ-MnO2 and ε-MnO2 has been prepared by a two-step electrochemical deposition method. According to the DFT calculations, the charge transfer and bonding between interfaces result in the generation of electronic states near the Fermi surface, giving δ/ε-MnO2 a more continuous distribution of electron states and better conductivity, which is conducive to the rapid insertion/extraction of Zn2+ and H+. Moreover, the strongly coupled Mn–O–Mn interfacial bond can effectively impede dissolution of Mn atoms and thus maintain the structural integrity of δ/ε-MnO2 during the cycles. Accordingly, the δ/ε-MnO2 cathode exhibits high capacity (383 mAh g–1 at 0.1 A g–1), superior rate performance (150 mAh g–1 at 5 A g–1), and excellent cycling stability over 2000 cycles (91.3% at 3 A g–1). Profoundly, this unique homojunction provides a novel paradigm for reasonable selection of different components.
研究领域:
材料科学
·
能源存储与转换
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2025
·
IF 19
Shuaizhou Chen,Xuewu Gao,Renyao Huang,Sha Fang,Xingzheng Peng,Mengke Li,Yi Feng,Xiongwei Qu,Xiaojie Zhang
Manganese-based oxides are promising cathode materials for aqueous zinc ion batteries (AZIBs) due to their high energy density and low cost. However, the cycling stability is severely limited by the sluggish reaction kinetics as well as the manganese dissolution. In this work, two pyridinium ionic porous organic polymers (iPOPs) composite ɛ-MnO 2 cathode materials, CN-POP@MnO 2 and PN-POP@MnO 2 , are prepared by an in situ composite method. The stable skeleton of iPOPs effectively prevents the structural collapse of the cathode. Its ionic sites and rigid network framework work together to disrupt the coordination environment of hydrated zinc ions, accelerating reaction kinetics and reducing cathode polarization. Therefore, the resultant batteries based on CN-POP@MnO 2 and PN-POP@MnO 2 cathodes exhibit excellent electrochemical performance. Especially for PN-POP-based batteries, the specific capacity is maintained at ≈96 mAh g −1 after 1500 cycles at 1 C, and the capacity attenuation rate is 0.017% per cycle.
研究领域:
材料科学
·
电化学
·
储能
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）