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
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产品关联
DOI
PubMed
高影响因子
GREEN CHEMISTRY
·
2023
·
IF 9.8
Shihao Su,Guojun Lv,Xuyang Zou,Jiangzhang Wang,Chaoyi Zhou,Yan Chen,Jialing Shen,Yangbin Shen,Zhongmin Liu
In the cyclic alkene epoxidation reactions using molecular oxygen as oxidant, aldehyde is generally added as co-oxidant to assist transition metal catalyst to activate the oxygen molecule, oxidizing cyclic alkene and producing the corresponding epoxide; however, the added aldehyde would be converted into byproduct carboxylic acid. Herein, we report the room-temperature tandem conversion of cyclic alkenes into 1,2-diols through the application of byproduct carboxylic acid as a catalyst for epoxide hydration reaction, realizing effective utilization of the byproduct and saving energy consumption. Four kinds of nanosized MnO2 specimens, including α-, β-, δ-, and γ-MnO2, were hydrothermally synthesized and applied as heterogeneous catalysts for the room-temperature tandem conversion of cyclohexene into 1,2-cyclohexanediol using molecular oxygen as oxidant and isobutyraldehyde as co-oxidant. The characterization results demonstrated that the obtained β-MnO2 sample had the maximum Mn4+/Mn3+ ratio of 1.42 and the minimum Oads/OLatt ratio of 0.34, consistent with its least oxygen vacancies evidenced by EPR measurement. Accordingly, the β-MnO2 sample revealed the quickest alkene epoxidation reaction rate and could achieve a 99.2% cyclohexene conversion within 1 h, and meanwhile, a 73.6% 1,2-cycloheanediol yield could be attained within 24 h. A plausible mechanism for the tandem conversion of cyclohexene into 1,2-cyclohexanediol over the β-MnO2 heterogeneous catalyst was proposed and further verified by quenching experiments and DFT calculations. Furthermore, the synthesized β-MnO2 catalyst sample could be reused more than ten times, and meanwhile, the tandem conversion way could be expanded to most of the cyclic alkene substrates, which demonstrated that the β-MnO2 catalyst was an active and stable heterogeneous catalyst for tandem conversion of cyclic alkenes into 1,2-diols.
研究领域:
催化化学
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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
Journal of Energy Storage
·
2024
·
IF 8.9
Rong Han,Yusong Pan,Chao Du,Yanlei Xiang,Yuanqing Wang,Hongwu Zhu,Chengjie Yin
Aqueous zinc ion batteries (AZIB) have become a research hotspot for energy storage systems (ESS) in recent years due to some advantages such as their low risk and low cost. However, the structural collapse during charging and discharging affects the reversibility of the battery , which is a very serious blow to manganese-based materials and will affect their subsequent development in batteries. Therefore, β-MnO 2 cathode materials doped by the rare earth element europium (Eu) were prepared by a simple hydrothermal method . Compared with β-MnO 2 , Eu-doped MnO 2 possessed a high specific capacity of 409 mA h g −1 at 0.2 A g −1 . The initial specific capacity of Eu-doped MnO 2 at 1 A g −1 was 200.23 mA h g −1 and the maximum discharge specific capacity of 254 mA h g −1 was reached at 128 cycles. The energy storage mechanism of the electrodes was investigated by ex-situ XRD and ex-situ XPS tests. It was found that Eu element doping to β-MnO 2 not only maintains the stability of the crystal structure during redox reaction, but also promotes the embedding reaction of H + /Zn 2+ . The combination of rare earth elements Eu and MnO 2 is a new direction in the development path of aqueous zinc ion batteries.
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
Journal of Water Process Engineering
·
2025
·
IF 6.7
Xuanying Cai,Tiansheng Chen,Zhenhua Dai,Peiren Ding,Yinhao Dai,Peng Fan,Jihong Xu,Yuankui Sun,Xiaohong Guan
In cold regions, the freezing process typically presents difficulties for the remediation of contaminated soil and groundwater. However, in this work we report a freeze-assisted activation of peroxydisulphate (PDS) by β -MnO 2 for the degradation of phenolic compounds. The results showed that 60.8 % of 2,4-dichlorophenol (2,4-DCP) could be abated in frozen solutions at an initial pH of 6.5 within 2 h, whereas only 12.4 % of 2,4-DCP disappeared in aqueous solutions under other identical conditions. This enhancing effect was highly associated with the well-known freeze concentration effect, which could decrease the solution pH at the ice grain boundary by 2.4 units. Electron spin resonance (ESR) spectroscopic analysis and experiments with quenching agents and D 2 O suggested that radicals and singlet oxygen were not the major reactive species involved in the β -MnO 2 /PDS system. Instead, Raman analysis indicated that PDS may be bound to the surface of β -MnO 2 to form a reactive inner-sphere complex of MnO 2 -PDS*, which is proposed to account for the oxidative degradation of 2,4-DCP in aqueous and frozen β -MnO 2 /PDS systems. Chronoamperometric experiments further showed the redox potential of the β -MnO 2 /PDS system was as high as 1.2 V. This work highlights the possibility of applying the freezing effect to accelerate PDS activation by minerals abundant in environment and thus offers a promising strategy for pollution remediation in cold regions.
研究领域:
环境科学
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化学
✓ 已验证
产品关联
DOI
高影响因子
IONICS
·
2021
·Vol. 27
·期 9
·3943-3950
·
IF 2.817
Cai Xinhao,Li Hanghang,Li Jing,Yan Huihui,Liu Yiwen,Yu Haoxiang,Yan Lei,Zhang Liyuan,Shu Jie
Rechargeable aqueous Zn/MnO 2 battery with mild electrolyte is exceedingly suitable for massive electrochemical applications due to its eco-friendliness and high safety. However, cycle stability is a crucial question in the practical application. Besides, the mechanism involved in energy storage is still controversial. Here, we show a Zn/MnO 2 battery with excellent cycle stability and provide the reasonable explanation of the operating mechanism. In this battery, the mild aqueous ZnSO 4 solution containing MnSO 4 and Na 2 SO 4 additives serves as the electrolyte and the β-MnO 2 nanorods serve as the cathode. As presented in the electrochemical tests, the specific capacity of β-MnO 2 nanorods is as high as 323.5 mA h g −1 , and its capacity retention is 94% after 1000 cycles at 3 A g −1 . The proposed energy storage mechanism is related to the reversible conversion reaction between β-MnO 2 and MnOOH. Therefore, the application of β-MnO 2 nanorods in aqueous Zn-ion battery has broad development prospects. Graphical abstract
研究领域:
电化学
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材料科学
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能源存储
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无机化学
·
纳米材料
✓ 已验证
DOI
高影响因子
CHEMOSPHERE
·
2018
·
IF 4.427
Xinxing Zhou,Yunzhi Xu,Xiaojie Mei,Ningjie Du,Rongmao Jv,Zhaoxia Hu,Shouwen Chen
An efficient and inexpensive catalyst for oxygen reduction reaction (ORR), polyaniline (PANI) and β-MnO 2 nanocomposites (PANI/β-MnO 2 ), was developed for air-cathode microbial fuel cells (MFCs). The PANI/β-MnO 2 , β-MnO 2 , PANI and β-MnO 2 mixture modified graphite felt electrodes were fabricated as air-cathodes in double-chambered MFCs and their cell performances were compared. At a dosage of 6 mg cm −2 , the maximum power densities of MFCs with PANI/β-MnO 2 , β-MnO 2 , PANI and β-MnO 2 mixture cathodes reached 248, 183 and 204 mW m −2 , respectively, while the cathode resistances were 38.4, 45.5 and 42.3 Ω, respectively, according to impedance analysis. Weak interaction existed between the rod-like β-MnO 2 and surficial growth granular PANI, this together with the larger specific surface area and PANI electric conducting nature enhanced the electrochemical activity for ORR and improved the power generation. The PANI/β-MnO 2 nanocomposites are a promising cathode catalyst for practical application of MFCs.
研究领域:
环境科学
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材料科学
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电化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Communications Chemistry
·
2022
·Vol. 5
·期 1
·1-8
·
IF 7.211
Xu Jiacheng,Zhang Tiantian,Fang Shiyu,Li Jing,Wu Zuliang,Wang Wei,Zhu Jiali,Gao Erhao,Yao Shuiliang
Understanding of the roles of oxygen species at reducible metal oxide surfaces under real oxidation conditions is important to improve the performance of these catalysts. The present study addresses this issue by applying a combination of operando diffuse reflectance infrared Fourier transform spectroscopy with a temperature-programmed reaction cell and mass spectrometry to explore the behaviors of oxygen species during H 2 oxidation in a temperature range of 25–400 °C at β-MnO 2 surfaces. It is revealed that O 2 is dissociated simultaneously into terminal-type oxygen (M 2+ -O 2– ) and bridge-type oxygen (M + -O 2– -M + ) via adsorption at the Mn cation with an oxygen vacancy. O 2 adsorption is inhibited if the Mn cation is covered with terminal-adsorbed species (O, OH, or H 2 O). In a temperature range of 110–150 °C, OH at Mn cation becomes reactive and its reaction product (H 2 O) can desorb from the Mn cation, resulting in the formation of bare Mn cation for O 2 adsorption and dissociation. At a temperature above 150 °C, OH is reactive enough to leave bare Mn cation for O 2 adsorption and dissociation. These results suggest that bare metal cations with oxygen vacancies are important to improve the performance of reducible metal oxide catalysts.
研究领域:
催化化学
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材料科学
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表面科学
✓ 已验证
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2022
·
IF 10.383
Zhao Wang,Yurou Wang,Yuxuan Lin,Gang Bian,Hai-Yang Liu,Xiang Li,Jun Yin,Jian Zhu
Aqueous zinc-ion batteries (ZIBs) have gained wide attention for their low cost, high safety, and environmental friendliness in recent years. β-MnO2, a potential cathode material for ZIBs, has been restricted by its small channels for efficient charge storage. Herein, β-MnO2 nanorods with oxygen vacancies are fabricated by a K+-doping strategy to improve the performance of ZIBs. The assembled batteries exhibit a capacity of 468 mAh g–1, a power density of 2605 W kg–1, and an energy density of 179 Wh kg–1, which outperforms most reported ZIBs. Such a performance is owing to the synergistic combination of the oxygen vacancies in β-MnO2 and concurrent deposition of ε-MnO2 from Mn2+ in the electrolyte. Furthermore, superior cycling stability with negligible capacity decay in these batteries is demonstrated over 1000 cycles at a high current of 2 A g–1. This study reveals the importance of oxygen vacancies and Mn2+ deposition effect in understanding the mechanism of charge storage in MnO2-based ZIBs.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2020
·
IF 4.65
Wanwei Jiang,Xijun Xu,Yuxuan Liu,Liang Tan,Fengchen Zhou,Zhiwei Xu,Renzong Hu
Aqueous zinc-ion batteries have emerged as prospective energy storage devices to partly replace organic ion batteries due to their high safety and eco-friendliness. Providing multifold synthesis methods of cathode materials is essential for Zn-ion battery development. Here, we demonstrated a practical strategy for the large-scale fabrication of high performance β-MnO 2 @C hybrid cathode materials by plasma assisted milling (P-milling). After P-milling for 10 h, the porous hybrid microparticles consisted of MnO 2 nanocrystallites , which combined and wrapped with the thin carbon layer derived from expanded graphite. The pores among the β-MnO 2 @C particles facilitated electrolyte infiltration during continuous cycling, while combining with carbon greatly enhanced the conductivity of the hybrids and helped to alleviate MnO 2 dissolution. Therefore, the β-MnO 2 @C hybrids delivered excellent cycle stability, with a high capacity of 130 mAh g −1 for 400 cycles at a current rate of 300 mA g −1 in an aqueous Zn(CF 3 SO 3 ) 2 electrolyte. This capacity retention was amongst the highest reported so far for MnO 2 -based cathode materials for Zn-ion batteries.
研究领域:
材料科学
·
能源存储技术
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
·
IF 6.2
Shenghai Xin,Xiaoping Dong,Duolong Jin,Liying Yang,Dandan Su
Aqueous zinc-ion batteries (RZIBs) are one of the favorable complementary candidates for lithium-ion batteries. The cathode material determines the whole performance. Herein, β-MnO 2 /3D GPE-CNTs hybrid cathode materials were fabricated by intermittent high-energy vibratory ball milling method. It delivered a higher specific discharge capacity of 313.31 mAh·g −1 and excellent cycling stability compared to the bare β-MnO 2 sample. Morphological characterizations revealed that the enhanced electrochemical performance of the β-MnO 2 /3D GPE-CNTs hybrid was mainly attributed to the three-dimensional framework structure, large specific surface area, and good conductivity of GPE-CNT, as well as its resulting particle refinement with uniform dispersion and partial suppression of grain amorphization . This article provided a new sight of fabricating Mn-based materials/conducting carbon material hybrid for good performance cathode in RZIBs.
研究领域:
材料科学
·
能源存储技术
✓ 已验证
产品关联
DOI
高影响因子
IONICS
·
2024
·Vol. 30
·期 10
·6047-6059
·
IF 2.4
Jin Duolong,Dong Xiaoping,Liu Jiankai,Pang Qianran,Xin Shenghai,Yang Liying,Wang Cuibiao
With the continuous development of new energy application technology, there is an increasingly urgent need for the safety and affordability of new energy storage products. In recent years, aqueous zinc-ion batteries based on mild aqueous electrolytes have garnered widespread attention as a potential replacement for traditional lithium-ion batteries. However, the limited capacity and low operating voltage of aqueous zinc-ion batteries restrict their widespread application. For this reason, sulfuric acid was added to the electrolyte, which effectively promotes the two-electron conversion of MnO 2 /Mn 2+ during the discharge process. This enhancement results in the high voltage segment of the batteries’ discharge phase offering a higher reversible specific capacity. The results showed that the batteries with 0.1 M H 2 SO 4 added to the electrolyte had a reversible discharge-specific capacity of up to 536.07 mAh·g −1 at a current density of 100 mA·g −1 . The activated batteries exhibited a reversible specific capacity of 85.11 mAh·g −1 even at a high current density of 1 A·g −1 . Furthermore, the capacity retention rate after 1000 cycles was 88.3%. Moreover, the activation rate of the batteries was faster with the addition of H 2 SO 4 , and the average operating potential increased compared to the batteries without H 2 SO 4 in the electrolyte. This provides an effective solution for the practical application of aqueous zinc-ion batteries in power grids.
研究领域:
电化学
·
能源存储技术
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Catalysis
·
2025
·
IF 13.1
Shihao Su,Guojun Lv,Jialing Shen,Fuxin Wang,Lachgar Oussama,Yan Chen,Shengnan Xu
In the tandem synthesis of 1,2-cyclohexanediol, solvents such as acetonitrile are often added to eliminate the immiscibility of cyclohexene with water and accordingly strengthen the interphase mass transfer; however, the usage of solvents artificially increases the solvent separation procedure, enhancing the energy consumption and decreasing the economic benefits of the reaction process. Hence, the development of the solvent-free Pickering interfacial tandem catalysis of cyclohexene to 1,2-cyclohexanediol is extremely appealing. In this study, β-MnO2 and Mn2O3 were prepared by calcining γ-MnO2 synthesized with the hydrothermal synthesis method and concurrently served as a colloidal emulsifier and a heterogeneous catalyst in the Pickering interfacial tandem catalysis of cyclohexene to 1,2-cyclohexanediol at room temperature in the presence of the oxidant molecular oxygen and the co-oxidant isobutyraldehyde. The prepared β450-MnO2 sample revealed the best tandem catalysis performance, achieving a cyclohexene conversion of 99.4% and a 1,2-cyclohexanediol selectivity of 83.6% within 4 h of reaction, which can be ascribed to the highest Mn4+/Mn3+ ratio and the greatest concentration of oxygen vacancies as well as the most stable Pickering emulsion. At the same time, density functional theory (DFT) studies further confirmed that isobutyraldehyde and molecular oxygen could be more easily adsorbed and activated by β450-MnO2 in comparison with the other catalyst samples, benefiting its eminent catalytic epoxidation performance. In addition, a possible reaction mechanism for the β450-MnO2 catalyst catalyzing cyclohexene into 1,2-cyclohexanediol in the Pickering interfacial tandem catalytic reaction system was put forward and validated through quenching experiments as well as in situ infrared characterization. The synthesized β450-MnO2 catalyst exhibited reusability for greater than 5 cycles, and meanwhile, the Pickering interfacial tandem catalytic reaction system can be expanded to a spread of linear and cyclic alkene substrates, highlighting the superiority of the β450-MnO2 catalyst. These findings verify that the synthesized β450-MnO2 catalyst is capable of being utilized as an efficient and stable catalyst for the Pickering interfacial catalytic conversion of alkenes into 1,2-diols at room temperature.
研究领域:
化学工程
·
催化科学
✓ 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）