Nano Energy
·
2022
·
IF 19.069
Yanhua Cui,Zengkai Wang,Binrong Li,Yan Yan,Ruibo Xu,Minjia Meng,Yongsheng Yan
Piezoelectric materials have been widely used in photocatalytic systems as it forms a built-in electric field to facilitate the migration of photo-induced charge-carriers. Herein, we report a three-dimensional (3D) porous g-C 3 N 4 /LiNbO 3 /PVDF membrane with an enhanced fluid-induced piezoelectric field for photocatalytic hydrogen evolution reaction (HER). The freezing phase inversion strategy is critical to the formation of piezoelectric sensitive β phase PVDF. The unique 3D porous membrane structure and the fluid-induced piezoelectric potential synergistically contribute to the HER efficiency under white light illumination. The as-prepared g-C 3 N 4 /LiNbO 3 /PVDF piezoelectric photocatalytic membrane (19.6875 cm 2 in size) exhibited HER rate of 136.02 µmol h −1 , which was even higher than that of the g-C 3 N 4 /LiNbO 3 powder sample (111.8 µmol h −1 ) with the identical mass of catalyst particles . In-situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) demonstrates a better water affinity of the porous g-C 3 N 4 /LiNbO 3 /PVDF piezoelectric membrane prepared by the freezing phase inversion than other PVDF membranes prepared by traditional phase inversion and vacuum drying methods. Piezoelectric force microscopy (PFM), in-situ piezoelectric and piezoelectric current measurements further visualized the fluid-induced piezoelectric field on 3D g-C 3 N 4 /LiNbO 3 /PVDF membrane, by which boosting the HER efficiency.
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CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Cheng Han,Huan Zhang,Quan Chen,Tao Li,Lingjian Kong,Hui Zhao,Lirong He
Directional sensors endowed by inherent anisotropic structure have drawn great attention in intelligent sensing systems. Unidirectional lyophilization is the mainstream technique to architect anisotropic structure particularly for water dispersible systems as the ice template can be readily removed at the melting point of water (0 °C). However, it is impractical for water insoluble polymers such as piezoelectric polymer systems as it features extremely low lyophilization temperature (for instance, −61 °C). So far, no piezoelectric polymer derived anisotropic devices has been realized. In this work, for the first time, we succeeded the constructing of anisotropic PVDF/Mxene device with directionally oriented micropores through delicate formulation design which enables the maintaining of oriented template even at temperature above 0 °C. As a result, the as-fabricated PVDF/Mxene composite foam exhibits distinct anisotropic behavior, featuring compressive modulus along the direction of penetrating microchannels being approximately 1.7 times of that in the orthogonal direction. The anisotropic foam is applied as directional sensor with piezo-current as the output signal, which displays a 3.93-fold higher sensitivity difference in the direction perpendicular to the microchannel than in its orthogonal direction. Moreover, the foam exhibits the highest sensitivity of 41.3nA/kPa over pressure range of 2.5–20 kPa, which outperforms state-of-the-art polymer piezoelectric sensors. This novel strategy provides a practical avenue for architecting water-insoluble polymer-derived devices with anisotropic structure in a green and energy-saving manner, which could spur innovations from the fields of electromagnetic interference shielding, energy storage, piezoresistive, thermal insulation and so on wherever anisotropic characteristic is desired.
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COMBUSTION AND FLAME
·
2021
·
IF 4.185
Chun Zhang,Huiqing Mao,Rui Cui,Xiandie Zhang,Jing Yang,Jie Ji,Xiang Zhou
High content of active component, low electrostatic sensitivity and superior long-term storage stability endow n-Si powder unique advantages for application in nanoenergetic composites. In this study, hydrophobic and corrosion-resistant Si@PVDF nanostructured energetic films with different stoichiometric ratios are successfully prepared by electrospinning technique . The energetic characteristics are systematically investigated in terms of thermal analysis, open-air combustion and constant-volume combustion. The results show that Si@PVDF films are microscopically composed of fibers with diameters of about 200–300 nm. With the increase of stoichiometric ratio, more and more n-Si aggregates are found on the surface of fibers. When Si@PVDF is stored in deionized water (50 °C) or NaOH solution (50 °C, 3 mol/L) for 72 h, around 100% and 73.3% of n-Si is retained. Si@PVDF can be thermally ignited, with appreciable heat and pressure output, and the combustion behaviors are strongly affected by the stoichiometric ratio and the environmental conditions. As a comparison, physically mixed Si/PVDF cannot maintain a self-sustained combustion. Through the coupled thermal analysis and mass spectrometry analysis, combined with the morphological and structural characterization of the solid residues , the reaction mechanism of Si@PVDF at a low heating rate is preliminarily obtained.
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DESALINATION
·
2022
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IF 11.211
Libing Zheng,Kai Wang,Deyin Hou,Xiaolin Jia,Zhichao Zhao
Membrane fouling and wetting were two unsolved issues for membrane distillation (MD), fostered an enduring pursuit of well-designed superhydrophobic membrane. In this work, a novel hierarchically-structured superhydrophobic membrane was prepared by grafting octavinyl-polyhedral oligomeric silsesquioxane (OVPOSS) onto polyvinylidene fluoride (PVDF) membrane via UV-induced thiol-ene click reaction after the hydroxylation and sulfhydrylation pretreatment . The POSS/PVDF membrane exhibited high roughness and superhydrophobicity, and the pore structure was optimized with smaller size but centralized distribution. For the fabricated superhydrophobic membrane with low sliding angle (about 7.5°), the maintaining of Cassie-Baxter state and the “slip effect” significantly mitigated membrane fouling and wetting, due to the retardation of the liquid invasion into the gas-solid interface. It was found that scaling was the leading fouling for the commercial PVDF membrane, and the interaction between Ca 2+ and carboxyl was the main organic fouling mechanism . While for the POSS/PVDF membrane, organic fouling via hydrophobic-hydrophobic interaction was the main membrane fouling and the scaling was significantly alleviated. The fabricated POSS/PVDF composite membrane had significant superiority over commercial PVDF membrane, which showed promising potential in challenging wastewater treatment . Additionally, this work also offered a new and facile method for superhydrophobic membrane fabrication.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2021
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IF 7.312
Linlin Yan,Xiaobin Yang,Yuanyuan Zhao,Yadong Wu,Richard Motlhaletsi Moutloali,Bhekie B. Mamba,Pavel Sorokin,Lu Shao
Membrane fouling is one of the difficult challenges that restrict the efficient application of membrane separation technology in oil/water separations. Hydrogel with strong hydration capability has been considered as an ideal material for preparing anti-oil-fouling coating for membranes. Although some hydrogel-based coatings have been developed for the membrane interface hydrophilization modification, controlling the morphology of gel layers and improving the flux of hydrogel coated membranes remains a difficult matter to resolve. In this study, we elegantly designed a new mineral-hydrogel coating with nanostructures to modify hydrophobic polyvinylidene fluoride (PVDF) microfiltration membranes by an alternate quaternary soaking strategy. Compared with the merely hydrogel-coated membrane, the pure water flux of novel mineral-hydrogel coating membrane increased by 214% and the permeation increased by 127% with the oil rejection rate of 99.6% at 0.4 bar. Most importantly, the newly-built mineral-hydrogel layer on porous support possessed excellent hydrophilicity, underwater super-oleophobic properties and superior anti-oil-fouling performance, which is greatly promising in oily sewage remediation. In addition, this mineral-hydrogel coating could also be constructed on other hydrophobic substrates successfully, such as commercial melamine resin. Our facile strategy for designing and constructing synergetic mineral-hydrogel architecture may also inspire other functional coatings with nanostructures.
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JOURNAL OF ENVIRONMENTAL MANAGEMENT
·
2021
·
IF 6.789
Hongji Li,Junfu Wang,Haoqi Fang,Hongda Xu,Haochen Yu,Tianyu Zhou,Chunbo Liu,Guangbo Che,Dandan Wang
The polyvinylidene difluoride (PVDF) membrane has received considerable attention as a flexible surface enhanced Raman scattering (SERS) substrate due to its excellent mechanical and physicochemical properties . However, the poor fouling resistance of PVDF membrane due to its intrinsic hydrophobic property limits its practical application. To address this, in this investigation, a SERS imprinted membrane is synthesized based on W 18 O 49 /Ag composites. Firstly, to promote hydrophilicity , N-vinyl-2-pyrrolidone (NVP) and triethoxyvinylsilane (VTES) are copolymerized by hydrolysis condensation and linked with engineered polyvinypyrrolidone (PVP) chains exposed on the surface of membrane. Furthermore, W 18 O 49 /Ag composites are dispersed on the membrane under the assistance of polydopamine (pDA) to promote the pollution resistance. Subsequently, in order to demonstrate the practical detection property, W 18 O 49 /Ag/PVDF membrane is selected as the SERS substrate to synthesize SERS imprinted membrane by precipitation polymerization for the selective detection of L-tyrosine. The characteristic results reveal that the SERS-imprinted membrane exhibits satisfactory hydrophilicity, and it can effectively degrade the pollutant molecules absorbed on its surface under ultraviolet light illumination. It is proved from the detection results that the LOD of WADP-MIMs for L-tyrosine reached 10 −9 mol L −1 when the concentration of L-tyrosine changed between 10 −3 –10 −9 mol L −1 . The correlation coefficient (R 2 ) is 0.994 and the limit of detection is 10 −9 mol L −1 . Meanwhile, it can be applied for the selective detection of L-tyrosine in mixture samples. Overall, this study presents a novel approach for the hydrophilic modification and pollution resistance enhancement of PVDF-based SERS imprinted membrane, which can be effectively utilized for the selective detection of practical samples.
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ACS Sustainable Chemistry & Engineering
·
2021
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IF 8.198
Changhai Zhang,Tongqin Zhang,Mengjia Feng,Yang Cui,Tiandong Zhang,Yongquan Zhang,Yu Feng,Yue Zhang,Qingguo Chi,Xianli Liu
The increasing energy problem and the demand of environmental protection raise higher requirements for the development of clean energy. Dielectric capacitors have attracted lots of attention as a supporting facility of energy storage and conversion for clean energy, but their further development is limited by the low energy storage performance. In this paper, all-organic composite dielectrics were reported, with a poly(methyl methacrylate) (PMMA)/poly(vinylidene fluoride) (PVDF) composite dielectric with different mixing ratios as the matrix and the organic molecular semiconductor with high electron affinity [6,6]-phenyl C61 butyrate acid methyl ester (abbreviated as PCBM) as fillers. The related test results show that with the increase in the doping contents of PCBM, the energy storage density increases obviously. When the doping content of PCBM is 0.9 wt %, the PMMA/PVDF-based organic composite dielectric possesses an optimal breakdown field of 685.67 kV mm–1, accompanying excellent energy storage performances (Ue, ∼21.89 J cm–3; η, ∼70.34%). The PVDF blended with PMMA strategy not only restrains the ferroelectric polarization loss of PVDF but also improves the breakdown strength of the polymer. More importantly, the polarization and breakdown strength of the composites can be synergistically enhanced by filling with PCBM fillers.
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Nanomaterials
·
2021
·Vol. 11
·期 12
·3201
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IF 5.076
Huijun Li,Xin Xu,Jiwei Wang,Xuefeng Han,Zhouqing Xu
Tetracycline (TC) contamination in water has progressively exacerbated the environmental crisis. It is urgent to develop a feasible method to solve this pollution in water. However, polluted water often contains oil. This paper reported a glass fiber (FG)-assisted polyvinylidene fluoride (PVDF) hybrid membrane with dual functions: high TC degradation efficiency in emulsion and oil-water separation. It can meet the catalytic degradation of tetracycline in complex water. This membrane was decorated by coating the glass fiber with PVDF solution containing hydrophilic graphene oxide hybridized NH2-MIL-101(Fe) particles. Moreover, due to its strong mechanical strength enhanced by the glass fiber, it can be reused as TC degradation catalysts for dozens of times without cracking. Thanks to the hydrophobicity of PVDF and the surface pore size of MOFs, the prepared membrane showed a good oil-water separation performance. Besides, the hydrophilic graphene oxide (GO) and NH2-MIL-101(Fe) improved the membrane’s anti-fouling performance, allowing it to be reused as the separation membrane. Therefore, the outstanding stability and recoverability of the membrane make it as a fantastic candidate material for large-scale removal of TC as well as oil-water separation application.Keywords:GO/NH2-MIL-101(Fe);PVDF membrane;glass fiber;tetracycline degradation;oil-water separation
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SENSORS AND ACTUATORS A-PHYSICAL
·
2021
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IF 3.407
Wancheng Qin,Peng Zhou,Xinyu Xu,Muhammad Sultan Irshad,Yajun Qi,Tianjin Zhang
The inclusion of inorganic piezoelectric fillers in the polymeric matrix of flexible ferroelectric polymer synergies the piezoelectricity for wearable electronics . Herein, hierarchical Bi 3.15 Nd 0.85 Ti 3 O 12 microspheres (H-BNdT MPs) embedded in the polymeric matrix of polyvinylidene fluoride–hexafluoropropylene (PVDF-HFP) based piezoelectric thin films are fabricated by using a facile and cost-effective film-forming method, drop-casting. The composites possess improved dielectric and ferroelectric properties comparing with that of the pure PVDF-HFP film without any electrical poling treatment. More importantly, the highest outputs of an open-circuit voltage of 20 V and a short-circuit current of 1.9 μA under the repeated mechanical force of 10 N at the frequency of 2 Hz were successfully achieved. The maximum power of the optimal PEH can reach as high as 4.6 mW, corresponding to a power density of 938 μW/cm 2 , and the output electricity can light up 10 LEDs with a full-wave rectifier circuit. The enhanced output performance is attributed to the high local stress around the H-BNdT MPs arising from the hollow hierarchical architecture of the inorganic fillers . The lead-free flexible PEH is also proved to have the ability to harvest the biomechanical energy of human movements, such as finger pinching, finger tapping , and fist punching. In particular, a PEH shoe is made to harvest energy from walking and running. This PEH is confirmed to be a potential energy harvester and effective self-powered generator to drive wearable devices .
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高影响因子
NEW JOURNAL OF CHEMISTRY
·
2021
·Vol. 45
·期 13
·6108-6119
·
IF 3.591
Siyi Li,Xuehui Zhao,Hongwei Zhang
It is very important to reduce the oxidation of free radicals in organic membrane materials for the stability and safety of drinking water production treatment processes. This paper presents a new method for the qualitative and quantitative determination of free radicals in sodium hypochlorite solution by electron spin resonance (ESR) and salicylic acid spectrophotometry. Experiments show that the free radical scavenging rate reaches over 86% after the addition of 0.5 wt% nano-particles. PVDF–PVP/TiO2 and PVDF–PVP/CNT modified membranes are prepared by blending polyvinylidene fluoride (PVDF) with nano titanium dioxide (nano-TiO2) and carboxyl-modified multi-wall carbon nanotubes (MWCNTs-COOH), and are treated in 2000 ppm sodium hypochlorite solution for 30 days. Through surface chemistry (FTIR, XRD), surface morphology (SEM), surface hydrophilicity (contact angle), surface electronegative (zeta potential) and mechanical properties tests, the changes of membrane properties are analyzed during aging. The experimental results show that the nano-particles have a quenching effect on free radicals and inhibit defluorination. It has been proved that under the action of nano-additives, the erosion of free radicals on the membrane material is reduced, the aging rate of the membrane material is decreased, and the chemical stability of the membrane material is improved. In this paper, the reason and mechanism of anti-aging of the nano-particle modified membrane are analyzed, which provides theoretical support for future membrane cleaning technology and prolonging the service life of the membrane.
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FIBERS AND POLYMERS
·
2021
·Vol. 22
·期 4
·972-980
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IF 2.153
Gui Cheng,Zhang Yike,Jin Rui,Song Yang,Li Rong,Xing Yanjun
Most previous work on the preparation of electrode materials has usually used to grind carbon nanofibers and add non-reactive binders, which lead to limited surface area and lower electrochemical performance in electrode materials. In this study, porous carbon nanofibers were prepared from non-miscible PAN/PVDF polymer blends by electrospinning and carbonization to obtain electrode materials with high performance and high specific surface area. In the process of preparing electrode materials, carbon nanofibers can be directly prepared as electrodes with high-performance and flexibility without adding any inactive materials, such as polymer binders or electronic conductors. Results showed that PF-C-50 has the maximum specific surface area of 773 m 2 g −1 and the specific capacitance as high as 181 F/g at the current density of 0.4 A/g and 134 F/g at the current density of 1 A/g. PF-C-80 exhibits a specific capacitance as high as 156 F/g at the current density of 0.4 A/g and 117 F/g at the current density of 1 A/g with the smallest IR drop and R ct . The prepared porous carbon nanofiber electrode improves the electrochemical performance and flexibility of the electrode material. These unique structures and characteristic materials can be excellent candidates for high-performance flexible electrodes, laying a good foundation for wearable devices.
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ACS Applied Materials & Interfaces
·
2021
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IF 9.229
Xingang Liu,Yinghao Shang,Jihai Zhang,Chuhong Zhang
Three-dimensional (3D) printing technologies have unparalleled advantages in constructing piezoelectric devices with three-dimensional structures, which are conducive to improving the efficiency of energy harvesting. Among them, fused deposition modeling (FDM) is the most widely used thanks to its low cost and wide range of molding materials. However, as the best piezoelectric polymer, a high electroactive β-phase poly(vinylidene fluoride) (PVDF) piezoelectric device cannot be directly obtained by FDM printing because the β-crystal is unstable at the molten state. Herein, we develop for the first time ionic liquid (IL)-assisted FDM for direct printing of β-PVDF piezoelectric devices. An IL can induce and maintain β crystals during melt extrusion and FDM printing, ensuring that the β-crystal in the printed PVDF device is as high as 98.3%, which is the highest in 3D-printed PVDF as far as we know. Furthermore, the shearing force provided by the FDM facilitates the directional arrangement of the dipoles, resulting in the printed PVDF device having self-polarization characteristics without poling. Finally, the piezoelectric output voltage of the 3D-printed PVDF device is 4.7 times that of the flat PVDF device, and its area current density (17.5 nA cm–2) is more than that of the reported 3D-printed PVDF piezoelectric device in the literature by two orders of magnitude. The one-step 3D printing strategy proposed in this paper can realize the rapid preparation of complex-shaped and lightweight self-polarized β-PVDF-based piezoelectric devices for energy harvesting.
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