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
·
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2019
·
IF 1.911
Zheng Zhang,Yuanhui Ji,Wei Chen
In this work, hollow manganese dioxide/gold nanoparticle (MnO 2 /GNPs) hybrid drug nanocarriers were prepared by coupling the gold nanoparticles (GNPs) with hollow structure manganese dioxide (MnO 2 ). Among them, GNPs have been used as near-infrared (NIR)-responsive element for photothermal effect under NIR laser irradiation. The glutathione (GSH)-responsive and pH-responsive performances of drug release were derived from hollow MnO 2 . Particularly, Doxorubicin hydrochloride (DOX) can be loaded into hollow MnO 2 /GNPs with the drug loading efficiency up to 82.0%. Moreover, the photothermal effect and GSH-/pH-responsive properties of hollow MnO 2 /GNPs were investigated. The hollow MnO 2 /GNPs possessed satisfactory drug release efficiency ( ca. 87.4% of loaded drug released in 12 h) and have high photothermal conversion efficiency, multiresponsive properties, and degradability. Finally, the kinetics of drug release was discussed in detail. Thus, our finding highlights that the multiresponsive nanocarriers are of great potential in the field of drug controlled release.
研究领域:
生物医学工程
·
纳米医学
·
药剂学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF DISPERSION SCIENCE AND TECHNOLOGY
·
2022
·
IF 2.042
Dongyang Zhou,Bin Gu,Jingjing Wang,Lili Ren,Guoguang Chen,Xiaolong Yang,Zhang Tao
In order to enhance the adsorption property of adsorbent, surface modification of existing adsorption materials has always been an interesting and challenging topic. Herein, the flower-like MnO2 nanowires (MNs) with three dimensions surface area and great adsorption property was successfully prepared by two-step hydrothermal route via MnO2 nanosheets in-situ growth on MnO2 nanowires. As an adsorbent, the MNs was evaluated for the removal of methylene blue (MB) from the aqueous solution. The effect of pH value, contact time, adsorbent dose, adsorption equilibrium, kinetics adsorption process, and isothermal models was investigated. The results showed that the maximum adsorption capacity of MNs of 2 g/L attained 34.247 mg/g at 5 minutes, and kinetics of MB were found fitting using the Langmuir model and the pseudo-first-order model, respectively. Furthermore, the adsorption capacity can be kept over 90% after five adsorption cycles. Therefore, the composite material can be a promising tool for developing a large variety of efficient and stable adsorbents by combining with different nanostructures for dyeing wastewater treatment.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Nano Materials
·
2023
·
IF 5.9
Xiaochan Liu,Xibin Yi,Jing Zhang,Xinfu Zhao,Sijia Liu,Tingwei Wang,Sheng Cui
Constructing heterostructure in nanomaterials is a scientific and efficient method to optimize the electrochemical properties of supercapacitors. Carbon aerogels (CAs) can enhance electrical conductivity and ion diffusion because of their three-dimensional porous structure, which is useful for fabricating electrodes. The moderate nanoheterostructures in aerogel nanomaterials have made great contributions to the optimization of application performance. Herein, a simple method for constructing the MnO2 nanoparticle/CA (MnO2/CA) heterostructure is proposed. The MnO2/CA heterostructure exhibits outstanding electrochemical capability in a three-electrode system, with a specific capacitance of 384 F/g, higher than 201 F/g of the CA, at a current density of 0.5 A/g. When MnO2/CA is used as a symmetric supercapacitor, it also exhibits a high energy density and power density, with the highest energy density of 33.78 Wh/kg. The prepared MnO2/CA shows improved performance for synergies in providing a high specific capacity and long cycle life.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Jueyu He,Hongwei Su,Guilong Yan,Li Wang,Dong Xiang,Zhenyu Li,Yuanpeng Wu,Jingyu Chen
Economic and efficient routes to achieve clean freshwater from oil-water mixtures and seawater have gained special attention to reduce the current water crisis, but still a challenge unsolved. Herein, poly (ether ether ketone) (PEEK) membrane, modified with MnO 2 layer, has been prepared by facile hydrothermal method to address this issue aforementioned. Given the existence of PEEK and underwater superoleophobicity/underoil superhydrophilicity of MnO 2 , the composite membrane exhibits strong mechanic properties (tensile stress: 110.2 MPa) and high separation efficiencies (99.9 %) for different oil–water mixtures under gravity. Additionally, our membrane could also effectively separate immiscible oil mixtures according to the dipole–dipole interaction. Furthermore, firm chemical stability against dichloromethane, N, N-Dimethylformamide, 1 M NaOH, 1 M HCl, and 1 M NaCl has been achieved. Most importantly, our membrane displays durable evaporation efficiency (2.63 kg m -2 h −1 ), high energy efficiency (85.9 %), and super salt tolerance under 1 sun irradiation, for solar-assisted seawater desalination.
研究领域:
材料科学
·
环境科学
✓ 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 CATALYSIS
·
2018
·
IF 6.759
Wenlong Zhen,Xiaofeng Ning,Meng Wang,Yuqi Wu,Gongxuan Lu
CdS is a promising visible-light responsive photocatalyst. However, the serious photocorrosion limits its application in photocatalysis. Here we report a novel strategy to overcome the disadvantage of CdS photocorrosion by fabricating peroxide decomposing active MnO 2 thin-layer over CdS nanowires (NWs) and assembling oxygen separation artificial gill to remove nascent formed oxygen in the dispersion. In the meantime, the using non-noble metal NiSe quantum dots (QDs) co-catalyst, NiSe/MnO 2 -CdS photocatalysts shows excellent photocatalytic over-all water splitting activity and remarkable stability under visible light irradiation without addition of any sacrifice reagent, 455.0 µmol h −1 g −1 of hydrogen evolution reaction (HER) rate and 5.20% of apparent quantum efficiency (AQEs) at 430 nm. Removing nascent formed O 2 from water by artificial gill can prevent the oxygen leading CdS photocorrosion. Photoluminescence spectra and photoelectrochemical measurements indicate that loading NiSe QDs and coating MnO 2 thin-layer can also improve transfer of the photogenerated charges in CdS. MnO 2 thin-layer can decompose formed hydrogen peroxide and enhance water splitting. Our results could potentially provide a new method for designing and fabricating more stable and efficient CdS-based nanocomposite photocatalysts toward versatile solar energy conversion.
研究领域:
材料科学
·
光催化
·
能源转换
✓ 已验证
DOI
高影响因子
Sustainable Energy & Fuels
·
2025
·
IF 4.1
Jingwen Li,Mingqiang Li,Shuailiang Xu,Haochen Weng
Chloride-ion batteries (CIBs) possess high theoretical energy densities and are promising successors to lithium ion batteries. In this study, we present a novel MnO2@V2O5@C cathode design. We introduced a water-in-salt system into the battery, which effectively solved the safety problem. This battery offered the advantages of high performance, low weight, low cost, high flexibility and enhanced safety. Furthermore, it achieved a discharge platform of up to 2.6 V, a maximum discharge capacity of 457.4 mA h g−1, and a cycle life of 1000. The cathode was lightweight, weighing only 0.02 g, and the battery used fewer materials, making it less expensive. It could be arbitrarily folded, punctured and burned (1300 °C) without explosion, and it could be operated normally before complete destruction. Thus, aqueous CIBs exhibit high safety. These advantages make this new type of chloride-ion battery a potential candidate for applications in automotive, portable devices, aerospace and other fields, and it opens a new path for the development of batteries.
研究领域:
材料科学
·
电化学
·
能源存储
✓ 已验证
产品关联
DOI
高影响因子
Science China-Chemistry
·
2019
·Vol. 62
·期 6
·727-731
·
IF 6.085
Zeng Xuecen,Zhang Xuejing,Liu Shuang,Yang Hao,Tao Zhanliang,Liang Jing
The γ-MnO 2 @CNT catalyst was prepared by in situ solid phase synthesis and first applied into sodium-air batteries (SABs). The initial discharge specific capacity of SABs with γ-MnO 2 @CNT catalyst can reach 8804 mA h g −1 and the overpotential gap is only 140 mV, which is better than the batteries that is catalyzed by α-MnO 2 @CNT and pure CNT. Besides, the batteries also exhibit excellent cycle performance, which can keep relatively stable for 246 cycles at 500 mA g −1 and 140 cycles at 1000 mA g −1 .
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2017
·
IF 4.233
Liying Jiang,Qichao Ye,Jianmeng Chen,Zhong Chen,Youli Gu
In this study, bentonite–Fe 3 O 4 –MnO 2 composite was synthesized by combining bentonite with Fe 3 O 4 and MnO 2 through co-precipitation. Vibrating-sample magnetometry , scanning electron microscopy with energy-dispersive X-ray spectrometry , transmission electron microscopy , Brunauer–Emmett–Teller measurements, and X-ray powder diffraction techniques were used to characterize the composite. The composite consists of Fe 3 O 4 nanoparticles orderly assembled on the surface of bentonite and an outer layer of MnO 2 sheets. The composite’s particles possess a saturation magnetization of 13.4–30.5 emu/g and a high specific surface area (203.89 m 2 /g). The adsorption behaviors of the composite in Cd(II) removal were evaluated by batch equilibrium experiments. Kinetic and isothermal data fit well the pseudo-second-order and the Freundlich models, respectively. Adsorption reached equilibrium within 30 min, and the Freundlich capacity of the composite was 35.35 mg/g. The adsorption capacity of Cd(II) increased with increasing pH and was dependent on the ionic strength . Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy showed the combination of surface hydroxyl groups of the composite and Cd(II) in the solution. The prepared composite can be easily recycled and reused by taking advantage of its magnetic properties . The results show that the designed composite is a promising absorbent for the treatment of Cd-contaminated water.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Yijiao Zhang,Yanming Wang,Haiying Huo,Pu Zhang,Xiaoliang Zhang,Hongwei Che,Jingbo Mu,Zhixiao Zhang,Ping Li,Chunxia Wu
A 2D/1D/0D ternary heterostructure was fabricated that combined the accumulative merits of each component to exhibit superior performance through synergistic effects. This study adopted a strategy based on integrating 2D MXene, 1D tubular MnO 2 , and 0D Ag nanospheres into one electrode to obtain a ternary heterogeneous layered structure composite electrode. Utilizing the collaborative and intensive outcomes from MXene, MnO 2 , and Ag, the resulting MXene/MnO 2 /Ag composite electrode achieved an exemplary specific capacitance of 880.8 F g −1 at 2 A g −1 . In this study, an asymmetric supercapacitor (ASC) was developed and fabricated using the MXene/MnO 2 /Ag composite for the anode, commercial activated carbon as the cathode. Consequently, in a two-electrode setup, the resulting devices displayed an admirable specific capacitance of 112.5 F g −1 at 3 A g −1 . After being cycled 5000 times, the device maintained 85.0 % of its original capacitance under charge-discharge conditions. Furthermore, the ASC device demonstrated a pronounced energy density of 39.9 Wh g −1 during cycling with a corresponding power density of 2955.8 W kg −1 . These results showed that the dimensionally combined MXene/MnO 2 /Ag nanoarchitectonic electrodes offered considerable application potential for enhancing energy storage in supercapacitors.
研究领域:
材料科学
·
能源存储
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
Science Bulletin
·
2024
·
IF 18.8
Wei Lv,Zilei Shen,Junlin Liu,Xudong Li,Fang Ding,Dongyue Zhang,Licheng Miao,Xuefeng Lyu,Ruijie Li,Miaomiao Wang,Yiming Li,Jingwen Meng,Chao Xu
In this study, we successfully synthesized a δ-MnO 2 cathode with O vacancies, encapsulated by C derived from pyromellitic acid, using a facile hydrothermal method followed by annealing in an Ar atmosphere. The cathode’s structural stability and charge transfer kinetics are enhanced by inhibiting the formation of the by-product Zn 4 SO 4 (OH) 6 ·4H 2 O, regulating the Mn valence state, and suppressing the Jahn–Teller effect through the synergy of C encapsulation and O vacancies. This results in remarkable electrochemical performance, including a large capacity of 421.2 mAh g −1 at 0.1 A g −1 , a high specific energy density of 595.53 Wh kg −1 , and exceptional long-cycle life stability with 90.88% over 4000 cycles at 10 A g −1 , together with superior coulombic efficiency (∼100%) in pure ZnSO 4 electrolyte. Moreover, the cathode materials demonstrate specific antitumor efficacy. In brief, this work introduces an in situ synthetic C encapsulated δ-MnO 2 with O vacancies expected to be applied in both large-scale energy storage and biomedicine.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）