JOURNAL OF POWER SOURCES
·
2019
·
IF 7.467
Yunzhao Liu,Xiaowei Chi,Qi Han,Yuexiu Du,Jiaqi Huang,Yu Liu,Jianhua Yang
Rechargeable Zn-ion batteries (ZIBs) have attracted extensive attention, but their practical application is hindered by the limited cycling life and complicated preparation process of cathode materials . Here, we develop a facile yet scalable chemical precipitation/spray-granulation combined methodology for the fabrication of α-MnO 2 nanofibers/carbon nanotubes hierarchically assembled microspheres (α-MnO 2 /CNT HMs) as the cathode material for aqueous ZIBs . The α-MnO 2 evenly anchoring to the CNTs-based framework shows significantly increased tap density compared with pristine α-MnO 2 , which can effectively enhance the electrochemical stability. Owing to the synergistic merits of highly conductive carbon nanotubes network and α-MnO 2 nanofibers with desirable structure features, within our knowledge, the highest areal energy density of 0.98 Wh cm −2 at 0.2 A g −1 and the record cycling stability with 96% capacity retention over 10000 cycles at 3 A g −1 among the reported cathodes for ZIBs are achieved. Zn 2+ and H + co-insertion reaction mechanism with high reversibility is further revealed. Fast kinetic of the H + insertion/extraction process renders the cell excellent cycling stability. Facile preparation of nanofibrous α-MnO 2 based micro-composite, cost benefit of the source materials, and the superior battery performance provide new approaches for the practical applications of ZIBs.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2019
·
IF 5.107
Chun Huang,Yulan Wang,Miao Gong,Wei Wang,Yang Mu,Zhen-Hu Hu
The discharging of Rhodamine B (RhB) from wastewater has caused huge environment pollution. Peroxymonosulfate (PMS) oxidation is an effective way to remove it from wastewater. However, finding an environmentally friendly metal to activate PMS is a key step for the oxidation process. In this study, nanorod α-MnO 2 loaded palygorskite (α-MnO 2 /Pal) was fabricated by a simple hydrothermal method. The analysis of field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) confirmed the loading of α-MnO 2 on the surface of Pal and characterized the surface of the composite. The surface area of α-MnO 2 /Pal composite was 159.13 m 2 /g, which was much higher than that of Pal and α-MnO 2 . The Pal, α-MnO 2 , Mn 2+ , and α-MnO 2 /Pal were used to activate PMS for RhB degradation. Nearly 100% RhB degradation was obtained in α-MnO 2 /Pal + PMS system in 180 min and in α-MnO 2 + PMS system in 300 min, while only 50% degradation was obtained in Pal + PMS system and 71.4% degradation in Mn 2+ + PMS system in 300 min. The degradation fitted the pseudo-first-order reaction kinetics well with rate constant of 0.02041 min −1 for α-MnO 2 /Pal + PMS system, 0.01192 min −1 for α-MnO 2 + PMS system, and 0.00435 min −1 for Mn 2+ + PMS system, respectively. The factors affecting RhB degradation were further investigated. The RhB degradation efficiency increased with the increase of α-MnO 2 /Pal dosages, PMS dosages and temperatures. The degradation was inhibited at pH > 5.5, while was favorable at pH < 5.5. The major reactive radicals responsible for RhB degradation classified by radical quenching experiment were O 2 − and 1 O 2 . The possible mechanism was further proposed based on the results. The α-MnO 2 /Pal composite showed nearly 50% mineralization ratio in the presence of PMS and an excellent reusability. The results from this study revealed that α-MnO 2 /Pal composite is an effective catalyst to activate PMS for RhB degradation.
研究领域:
环境科学
·
催化化学
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产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
·
2021
·Vol. 46
·期 3
·2737-2747
·
IF 5.164
Yueheng Fan,Aiming Wu,Xiaohui Yan,Shuiyun Shen,Zhang Junliang
Summary Both the activity and structure of a cathode, when it is used in non-aqueous Li-O 2 batteries, play a prominent role in the aspects of durability and capacity. In this work, α-MnO 2 /prGO hybrid nanocomposites with a three-dimensional (3D) porous structure are proposed to act as the cathode to improve the battery performance. Highly active α-MnO 2 /prGO nanocomposites with different mass ratios are synthesized through a two-step template method and a subsequent annealing process. It is found that the optimal 50% α-MnO 2 /prGO cathode exhibits outstanding discharge capacity of 13 294 mAh g −1 under the condition of 100 mA g −1 . Meanwhile, with the limited capacity and currency density of 1000 and 100 mA g −1 , respectively, the battery maintains excellent durability for 239 cycles. Significantly, it is clear that the excellent electrochemical performance of the nanocomposites is strongly associated with the synergistic effect of their distinct porous architecture and the ORR/OER catalytic activity.
研究领域:
材料科学
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电化学
·
能源存储与转换
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2014
·Vol. 2
·期 48
·20729-20738
·
IF 0
Zhiwei Wen,Wen She,Yuesheng Li,Renchao Che
Enhancement of the electrochemical performances of electrode materials is a great challenge in the electrochemical capacitor field. Herein, a novel paramecium-like α-MnO2 hierarchical hollow structure used as an electrode material has been successfully prepared, which possesses an ultra-high specific surface area (285 m2 g−1), uniform crystal orientation, and high specific capacitance (554.3 F g−1 at 1 A g−1) and exhibits 97.9% capacitance retention after 5000 cycles. The earlier carbonaceous coating transformed from dopamine plays an important role in forming this novel paramecium-like morphology. The shells are constructed of ultra-thin α-MnO2 nanoflakes with highly uniform and preferentially exposed [001] crystal orientation. The high specific surface area increases the electrolyte–electrode contact area and the unique orientated structure effectively facilitates ion transportation. Quasi in situ electron energy-loss spectroscopy (EELS) analysis for both hierarchical hollow structures and commercial products at different charge–discharge stages indicates that Mn in our products can be almost completely restored to its original oxidation valence state due to a complete redox reaction, while there is still a fraction of Mn in the commercial product that cannot be restored, which causes the reduction of specific capacitance and retention. All the results suggest that this novel α-MnO2 hierarchical hollow structure with selective growth orientation might become an attractive type of electrode material.
研究领域:
材料科学
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电化学
✓ 已验证
产品关联
DOI
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Muhammad Arif,Ayaz Mahsud,Amjad Ali,Shipeng Liao,Jiawei Xia,Hai Xiao,Mohammad Azam,Tahir Muhmood,Zhansheng Lu,Yinjuan Chen
The construction of visible-light-driven hybrid heterostructure photocatalysts is of great significance for environmental remediation, although the utilization of strong visible-light response photocatalysts with high efficiency and stability remains a major challenge. On the other hand, defect engineering is an excellent way to introduce metal cation vacancies in materials, thereby ensuing in highly enhanced catalytic performance. Inspired by this, we effectively constructed a built-in interface α-MnO 2 /Bi 2 WO 6 heterostructure with abundant intimate interfaces and defective Mn 3+ /Mn 4+ active sites for photocatalytic tetracycline hydrochloride (TC-HCl), hexavalent chromium Cr 6+ reduction, and Escherichia coli ( E. coli ) inactivation. The experimental results, such as the active species test and X-ray photoelectron spectroscopy, indicated that the defective sites Mn 3+ /Mn 4+ , surface oxygen vacancies, and Bi (3+x)+ boosted the visible light absorption, and highly enhanced the photoinduced charge separation/transfer. Furthermore, experimental and DFT calculations reveal the high charge density at the built-in interface heterostructure and the Z-scheme charge transfer mechanism during the photocatalytic process. The results further reveal that O 2 − and 1 O 2 are the main reactive active species contributing to the photocatalytic reaction. The exceptional TC-HCl decomposition activity of the α-MnO 2 /Bi 2 WO 6 heterostructure (97.56%, 2.31, and 2.04 times higher than bulk), enhanced reaction kinetics (K app = 0.041 min −1 , 6.4, and 5.2 times higher than bulk), removal rate of 80.3%, Cr 6+ reduction to Cr 3+ (98.56%, K app = 0.0599 min −1 ), and almost 100% bacterial inactivation compared to bulk α-MnO 2 (42.22%) and Bi 2 WO 6 (47.76%), were mainly due to the enhanced charge separation/transfer at the built-in interface and high charge density. This study opens new horizons for constructing Z-scheme MnO-based interface heterostructures with abundant defect sites for exceptional photocatalytic applications.
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
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Qun Yu,Yuhang Yang,Yan Xu,Yuqiao Wang,Qingdong Qin
The application of metal doping has emerged as a prominent approach for modifying transition-metal-based heterogeneous catalysts in activating peroxymonosulfate (PMS). Herein, silver-doped α-MnO 2 (Ag-α-MnO 2 ) was synthesized via a one-step hydrothermal approach and utilized for activating PMS to degrade sulfamethoxazole (SMX). The catalyst was systematically characterized and examined to determine that the efficient dispersion of Ag increased the specific surface area and pore volume of α-MnO 2 . The degradation experiments demonstrated that SMX could be efficiently degraded by a combination of PMS and Ag-α-MnO 2 within 60 min. The apparent kinetic rate constant was 0.039 min −1 , which was approximately ten times higher than that of α-MnO 2 . The impacts of external water conditions on catalytic performance and the stability of Ag-α-MnO 2 were subsequently investigated. Density functional theory calculations revealed that Ag as a crucial active center reduced the PMS adsorption energy, promoted electron transfer, and orchestrated electron distribution. EPR spectra, quenching experiments, electrochemical tests, and XPS analysis were performed to validate the radical and non-radical mechanisms, including SO 4 − , OH, O 2 − and 1 O 2 . The two redox cycles of Ag + /Ag 0 and Mn 4+ /Mn 3+ on the surface of Ag-α-MnO 2 contributed to the activation of PMS. Additionally, probable degradation pathways for SMX were presented. This study provides an initially valuable insight into the cooperative mechanism of PMS activation for SMX degradation employing Mn-based catalysts doped with precious metal silver.
研究领域:
环境科学
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催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2023
·
IF 6.7
Chengfu Deng,Zhibing He,Jinglin Huang,Lei Liu,Yansong Liu,Tao Wang,Guo Chen,Yong Yi,Kai Du
Aqueous asymmetric sodium-ion supercapacitors (ASSCs) with high energy density assembled from all-inorganic materials are expected to provide high-efficiency power sources for intelligent electric vehicles and off-grid systems. However, it is still challenging to fabricate high-performance positive materials by a simple method and rationally assemble ASSCs to meet the demand of ultralong cycle life and high energy/power density. Here, a simple pre-activation strategy was introduced into the α-MnO 2 electrode with a microcrystalline nanosheet structure to improve the Na-storage performance. The sodium-ions concentration was optimized by tuning charge-discharge parameters. Impressively, the pre-activated electrode achieved superior capacitance retention after 10,000 cycles, high volumetric capacitance of 377 F cm −3 and low charge transfer resistance of 5.9 Ω. Based on the facile operability of the proposed pre-activation strategy, it can be expected to be easily ported to other Li/K/Zn-storage, providing a novel avenue for the exploration of positive electrode materials with outstanding electrochemical behaviors. A novel ASSC was fabricated by matching α-MnO 2 //WO 3 electrodes, exhibiting wide voltage of 2.0 V, high energy/power density (0.965 W h cm −3 /65.2 W cm −3 ) and ultralong cycle life. This work proposes a simple strategy to develop high-performance positive materials and assemble ASSC with high energy/power density and long-term stable operation.
研究领域:
电化学
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材料科学
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能源存储
✓ 已验证
DOI
高影响因子
Reaction Kinetics Mechanisms and Catalysis
·
2025
·
IF 1.7
Cheng Lijun,Lei Juan,Ren Xiaoli,Chang Hong,Ju Baihe
In this study, a series of La-α-MnO 2 catalysts with different La doping amounts were prepared by hydrothermal method. It was found that the introduction of La could reduce the crystallinity of α-MnO 2 and increase the specific surface area of the catalyst. Furthermore, La doping can significantly weaken the Mn–O bond, increase the surface Mn 3+ and O ads content, and enhance the oxygen mobility and low-temperature reducibility. The catalytic results indicated that La doping could significantly improve the catalytic oxidation performance of toluene, and 1%La-α-MnO 2 catalyst exhibited the best catalytic activity for toluene oxidation. The toluene conversion rate reaches 90% when the reaction temperature is only 215 °C. In addition, 1%La-α-MnO 2 catalyst presented good stability and repeatability during 50 h durability test under water vapor.
研究领域:
催化化学
·
环境科学
·
材料化学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of the Taiwan Institute of Chemical Engineers
·
2023
·
IF 5.7
Dewei Wang,Zhaorui Sun,Xinliang Han
Background Aqueous non-metallic ammonium ions (NH 4 + ) have newly been developed as a promising charge carrier for electrochemical energy storage owing to their high safety, abundance, and tiny hydrated ionic size. Producing reliable electrode materials with excellent electrochemical performance, however, remains a significant issue. Methods we proposed a bidirectional chemical activation strategy, which effective coupling “in to out” and “out to in” etching manner, to synthesize foam-like porous carbon nanosheets (FCNSs) with the surface area much larger than that samples obtained from the unidirectional mode. Meanwhile, oxygen-deficient α‐MnO 2 nanorods can be rationally obtained through mild redox reaction, both of which display excellent capacitive performance in dilute (NH 4 ) 2 SO 4 electrolyte (0.5 M). Significant findings the as-synthesized FCNSs and oxygen-deficient α‐MnO 2 nanorods can deliver a specific capacitance of 257.5 F g −1 and 525.1 F g −1 , respectively, demonstrating their huge potential to assemble ammonium-ion hybrid supercapacitor (A-HSC). Benefitting from the feasible electrochemical performance for both anode and cathode, the resulting A-HSC displays a specific capacitance of 180.8 F g −1 (calculated based on both anode and cathode) within 0–1.6 V, and a low self-discharge rate, which outperforms the state-of-the-art A-HSC devices. Importantly, the energy storage mechanism has been elucidated from several ex-situ characterizations.
研究领域:
材料科学
·
电化学
·
能源存储
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2022
·
IF 6.371
Jiahao Zu,Weitao Jing,Xin Dai,Zheng Feng,Junjie Sun,Qiang Tan,Yuanzhen Chen,Yongning Liu
Lithium-sulfur (Li-S) batteries have attracted enormous attentions as new-generation energy storage devices due to their high theoretical energy density , high theoretical specific capacity, low cost and environmental friendliness. However, polysulfide shuttle and the growth of lithium dendrites significantly restrain the practical application of the Li-S batteries. In this work, a modified PP separator with nanoscale rod-like α-MnO 2 supported on carbon nanotubes was prepared. The α-MnO 2 @CNT modified separator can effectively inhibit the shuttle of polysulfide , enhance the electrochemical activity and accelerate the transfer of ions and electrons. The density functional theory (DFT) calculations demonstrate that α-MnO 2 @CNT can efficiently adsorb and catalyze the conversion of polysulfides. Due to these advantages, the α-MnO 2 @CNT-based Li-S battery delivers a initial discharge capacity of 1469 mAh g −1 at 0.05 C, 1039 mAh g −1 at 0.5 C and the capacity can still maintain 648 mAh g −1 over 500 cycles at 0.5 C (capacity decay rate of 0.075%). Expressly, the capacity decay rate is only 0.022% after 600 cycles at a high current density of 2 C. The excellent performance could be attributed to the α-MnO 2 @CNT modified separator not only accelerating the transmission of electrons but also effectively inhibiting the shuttle of polysulfides. Moreover, this work provides a better idea for practical applications of lithium-sulfur batteries in the future.
研究领域:
材料科学
·
电化学
·
能源存储
·
电池技术
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ENVIRONMENTAL ENGINEERING
·
2025
·Vol. 151
·期 8
·04025043
·
IF 1.6
Jie Zhang,Mengchen Zong,Ben Dong,Sijie Ge,Shilong He
Quinoline, as one of the typical toxic and refractory organic pollutants in coal chemical industry wastewater, poses a significant threat to human health and environmental quality. In this study, MnCexOy and MnFexOy catalysts were successfully synthesized by doping Ce3+ and Fe2+ into α-MnO2 at a molar ratio of 1∶10 and were applied to the process of catalytic ozonation for the degradation of quinoline. Additionally, a variety of characterization techniques were employed to elucidate the characteristics of the catalysts, including scanning electron microscopy, X-ray diffraction, Brunauer–Emmett–Teller (BET) analysis, X-ray photoelectron spectroscopy, H2-TPR, NH3-TPD. The results show that, in the catalytic ozonation system for quinoline removal, MnCexOy demonstrates excellent quinoline removal efficiency of 87.45%, which is higher than that of MnFexOy (78.83%) and unmodified α-MnO2 (62.67%). By introducing the surface hydroxyl masking agent HPO42−, the significant role of surface hydroxyl groups and oxygen vacancies in the catalytic degradation of quinoline by MnCexOy was further demonstrated. Exploring the surface characteristics of catalysts is beneficial for continued understanding of the active centers of catalysts. Research results will be helpful to the deep treatment and reuse of tailing water of coking wastewater.
研究领域:
环境科学
·
催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
Frontiers of Chemical Science and Engineering
·
2022
·Vol. 17
·期 2
·217-225
·
IF 4.803
Xie Jiwei,Liu Guijing,Wang Kaikai,Li Xueming,Bai Yusen,Gao Shanmin,Fan Leqing,Zheng Rundou
Aqueous zinc-ion batteries are attracting considerable attention because of their high safety compared with conventional lithium-ion batteries. Manganese-based materials have been widely developed for zinc-ion batteries cathode owning to their low cost, high security and simple preparation. However, the severe volume expansion and poor stability during charging and discharging limit the further development of manganese-based cathodes. Herein, superior α -MnO 2 @g-C 3 N 4 was successfully prepared for stable zinc-ion batteries (ZIBs) cathode by introducing g-C 3 N 4 nanosheets. Compared with pure α -MnO 2 , α -MnO 2 @g-C 3 N 4 has a specific capacity of 298 mAh·g –1 at 0.1 A·g –1 . Even at 1 A·g –1 , the α -MnO 2 @g-C 3 N 4 still retains 100 mAh·g –1 (83.4% retention after 5000 cycles), implying its excellent cycling stability. The α -MnO 2 @g-C 3 N 4 -based cathode has the highest energy density (563 Wh·kg –1 ) and power energy density (2170 W·kg –1 ). This work provides new avenues for the development of a wider range of cathode materials for ZIBs.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
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