Electrophoretic deposition of hybrid organic-inorganic PTFE/Al/CuO energetic film

Thermite films are typical energetic materials(EMs)and have great value in initiating explosive devices.However,research in thermite film preparation is far behind that of research in thermite powders.Electrophoretic deposition(EPD)is an emerging,rapid coating method for film fabrication,including of energetic composite films.In this work,a polytetrafluoroethylene(PTFE)/Al/CuO organic-inorganic hybrid energetic film was successfully obtained using the above method for the first time.The addition of lithocholic acid as a surfactant into the electroplating suspension enabled PTFE to be charged.The combustion and energy release were analyzed by means of a high-speed camera and differential scanning calorimetery(DSC).It was found that the combustion process and energy release of PTFE/Al/CuO were much better than that of Al/CuO.The main reason for the excellent combustion performance of the hybrid PTFE/Al/CuO system was that the oxidability of PTFE accelerated the redox reaction between Al and CuO.The prepared PTFE/Al/CuO film was also employed as ignition material to fire a B-KNO_3 explosive successfully,indicating considerable potential for use as an ignition material in micro-ignitors.This study sheds light on the preparation of fluoropolymer-containing organic-inorganic hybrid energetic films by one-step electrophoretic deposition.

Effect of TbF_(3)diffusion on the demagnetization behavior and domain evolution of sintered Nd-Fe-B magnets by electrophoretic deposition

We studied the magnetic properties and domain evolution of annealed and TbF3-diffused sintered Nd-Fe-B magnets using the electrophoretic deposition method.After TbF_(3)diffusion,the coercivity increased significantly by 9.9 kOe and microstructural analysis suggested that Tb favored the formation of the(Nd,Tb)_(2)Fe_(14)B shell phase in the outer region of the matrix grains.The first magnetization reversal and the dynamic successive domain propagation process were detected with a magneto-optical Kerr microscope.For the TbF_(3)-diffused magnet,the magnetization reversal appeared at a larger applied field and the degree of simultaneous magnetization reversal decreased compared with an annealed magnet.During demagnetization after full magnetization,the occurrence of domain wall motion(DWM)in the reproduced multi-domain regions was observed by the step method.The maximum polarization change resulting from the reproduced DWM was inversely related to the coercivity.The increased coercivity for the diffused magnet was mainly attributed to the more difficult nucleation of the magnetic reversed region owing to the improved magneto-crystalline anisotropy field as a result of Tb diffusion.

Effect of MgCl_(2) on electrophoretic deposition of TbF_(3) powders on Nd-Fe-B sintered magnet

Using electrophoretic deposition(EPD)method,the TbF_(3)powders were deposited on the surface of sintered Nd-Fe-B magnets,and the effects of MgCl_(2)on electrophoretic deposition and grain boundary diffusion were investigated.The results show that addition of 5 wt%MgCl_(2)can significantly improve the EPD efficiency and improve the adhesion of the coating by releasing local stress through the formation of special gully morphology.Combining with Biesheuvel equation,the effects of suspension concentration,voltage and time on EPD amount were studied.The Biesheuvel equation can be simplified asγ=AUSct/L,and A(=0.0141-0.0144)in this experiment was calculated to achieve the quantitative calculation of EPD amount.After heat treatment of 875℃×10 h+500℃×1 h,the coercivity of 48H(7 mm)sintered magnet with 0.3 wt%TbF_(3)increases from 18.5 to 22.4 kOe,with an increase of 21.1%.The core-shell structure was observed by a back-scattered scanning electron microscope(BSE-SEM),which proves that the addition of MgCl_(2)has no adverse effect on the grain boundary diffusion of Nd-Fe-B sintered magnets.

Electrophoretic deposition of graphene-based materials:A review of materials and their applications

Recently,graphene-based materials have been successfully fabricated by the electrophoretic deposition(EPD)technique and exhibited various extraordinary properties.Here,research progress of the field of graphene-based materials prepared by the EPD process in recent 5 years is reviewed,including graphene films,graphene/non-metal composites,graphene/metal-based nanoparticles composites,graphene/polymer composites.We also summarize the experimental deposition conditions and the applications of the deposited graphene-based materials that have been reported.It can be concluded that EPD is a simple and reliable manipulation technique and promises a bright future for the production of graphenebased materials in the field of advanced nanocomposite materials.Finally the current issues and outlook of the development direction of EPD in future are also proposed.

Electrophoretic deposition of a supercapacitor electrode of activated carbon onto an indium-tin-oxide substrate using ethyl cellulose as a binder

A transparent energy storage device is an essential component for transparent electronics.The increasing demand for high-power devices stimulates the development of transparent supercapacitors with high power density.A transparent electrode for such supercapacitors can be assembled via the electrophoretic deposition of an active material powder with a binder onto a transparent substrate.The properties of the binder critically influence the electrochemical behavior and performance of the resulting electrode.Ethyl cellulose(EC)is known as an eco-friendly,transparent,flexible,and inexpensive material.Here,we fabricated an electrode film with EC binder via electrophoretic deposition on an indium tin oxide(ITO)substrate instead of using the conventional polytetrafluoroethylene(PTFE)binder.The assembled electrodes with EC and PTFE were compared to investigate the feasibility of EC as a binder from different perspectives,including homogeneity,wettability,electrochemical behavior,and mechanical stability.The EC enabled the formation of a homogeneous film composed of smaller particles and with a higher specific capacitance compared with films prepared with PTFE.The annealing improved the adhesion strength of the EC because of its glass transition;however,its hydrophobic nature limited utilization of the active material for charge storage.Subsequent electrochemical activation improved the wettability of the electrode,resulting in an increased capacitance of 60 F g^(-1).Furthermore,even with the lower wettability of EC compared with that of PTFE,better rate performance was possible with the EC electrode.The increased mechanical stability after the annealing process ensured an excellent cycle life of 95%capacitance retention for 15,000 cycles.

Electrophoretic deposition and an investigation of co-dopants effect on luminescence property of Mg2SiO4:Eu3+phosphors

Forsterite particles doped with europium ions(Eu^(3+)) were synthesized via a solution combustion method. The effect of co-dopants on photoluminescence intensity was described. Different percentages of calcium(Ca^(2+)), zinc(Zn^(2+)), barium(Ba^(2+)) and strontium(Sr^(2+)) were added to the Mg_2SiO_4:Eu^(3+)host.The synthesized sample was characterized by X-ray diffraction, transmission electron microscopy,scanning electron microscopy, spectrofluorometer and the FTIR spectroscopy. X-ray diffraction(XRD)results revealed that dominant phase was forsterite in all samples. Additionally, a negligible amount of periclase phase was recognized in the samples. The average size of the synthesized particles was less than 200 nm. The presence of co-dopant led to an enhancement in the photoluminescent property of the synthesized samples. The maximum increase in photoluminescence intensity was obtained by Ba^(2+)ions as a co-dopant. Condensed films of photoluminescence particles were produced by utilizing electrophoresis technique to deposit particles. The results showed that polyvinyl pyrrolidone was the best surface modifier to raise the mass deposition of the samples on the substrate.

Electrophoretic deposition of silk fibroin coatings with pre-defined architecture to facilitate precise control over drug delivery

The therapeutic precision and clinical applicability of drug-eluting coatings can be substantially improved by facilitating tunable drug delivery.However,the design of coatings which allows for precise control over drug release kinetics is still a major challenge.Here,a double-layered silk fibroin(SF)coating system was constructed by sequential electrophoretic deposition.A mixture of dissolved Bombyx mori SF(bmSF)molecules and pre-made bmSF nanospheres at different ratios was deposited as under-layer.Subsequently,this underlayer was covered by a top-layer comprising Antheraea pernyi SF(apSF)molecules(rich in arginylglycylaspartic acid,RGD)to improve the cellular response of the resulting double-layered coatings.Additionally,model drug doxycycline was either pre-mixed with dissolved bmSF molecules or pre-loaded into pre-made bmSF nanospheres at the same amount before their mixing and deposition.The thickness and nanosphere content of the under-layer architecture were proportional to the deposition time and nanosphere concentration in precursor mixtures,respectively.The surface topography,wettability,degradation rate and adhesion strength were comparable within the double-layered coating system.As expected,RGD-rich apSF top-layer improved cell adhesion,spreading and proliferation compared with bmSF top-layer.Furthermore,the amount and duration of drug release increased linearly with increasing nanosphere concentration at fixed deposition time,whereas drug release amount increased linearly with increasing deposition time.These results indicate that the dosage and kinetics of loaded drugs can be quantitatively tailored by altering nanosphere concentration and deposition time as main processing parameters.Overall,this study illustrates the strong potential of pre-defining coating architecture to facilitate control over drug delivery.

Electrophoretic deposition of chitosan-bioglass^(■)-hydroxyapatite-halloysite nanotube composite coating

The composite coatings of chitosan(CS)-bioglass^(■)(BG)-hydroxyapatite(HA)-halloysite nanotube(HNT)were investigated and produced via electrophoretic deposition(EPD)technique.The utilization of CS as a dispersing,blending and charging agent for ceramic particles,including BG,HA and HNT,allowed the formation of CS-BG/HA/HNT composite,functionally graded composite(FGC)and bilayer film containing different layers.The results of scanning electron microscopy(SEM),energy-dispersive spectrometry(EDS),X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(FTIR)illustrate the composite in the form of the optimum distribution of ceramic components in the CS matrix with thickness of 28μm on titanium(Ti)substrate.Electrochemical impedance spectroscopy(EIS)and potentiodynamic polarization tests indicate that the corrosion resistance of the coated sample increases in corrected simulated body fluid(C-SBF)at 37℃.Finally,the apatiteinducing ability of CS-BG-HA-HNT is proved by the formation of carbonated hydroxyapatite particles on composite coating in C-SBF.

Electrophoretic deposition of Al_(2)O_(3)/ZrO_(2) layer with controllable thickness in ethanol medium

ZrO_(2) toughened Al_(2)O_(3)(Al_(2)O_(3)/ZrO_(2))ceramic layers with required thickness were prepared by electrophoretic deposition(EPD)method using ethanol suspensions with stabilizing agent of polyethyleneimine(PEI)under constant-voltage mode in this paper.The deposition of Al_(2)O_(3)/ZrO_(2) ceramic powders occurred on the titanium alloy cathode.A stable suspension with 1wt% PEI in ethanol at pH 5 was prepared in terms of the zeta potential and sedimentation of the suspension.The effects of the suspension concentration,applied voltage,deposition time and processing method of titanium alloy cathode on the coating thickness and morphology were investigated.The deposition layers on titanium alloys with smooth surfaces and thickness of 0.35–1.2 mm could be obtained by adjusting the aforementioned parameters.In addition,after being sintered at 1500℃ for 3 h in air atmosphere,ZrO_(2) toughened Al_(2)O_(3) ceramic layers became smooth and dense.

Additive Manufacturing of Metal Micro-ring and Tube by Laser-Assisted Electrophoretic Deposition with Laguerre-Gaussian Beam

We report a method for laser-assisted electrophoretic deposition using a Laguerre-Gaussian beam for maskless patterning of metal rings and tubes.These are structures of utmost importance,particularly in photonic devices.Metal nanoparticles,which are gathered in a colloidal solution by a laser trapping technique,are deposited on a substrate via electrophoresis.The deposition pattern is dependent on the focused spot shape during laser trapping.The intensity distribution of the Laguerre-Gaussian beam is ring-shaped.Rings with different inner diameters can be fabricated by varying the topological charge of the Laguerre-Gaussian beam.The equivalent inner diameters of the deposited rings with topological charges of 1,3,and 5 were 0.30,0.78,and 1.45μm,respectively.The inner diameter of the deposited ring with a topological charge of 1 was smaller than the wavelength of the laser beam(532 nm).A tube was also fabricated with a topological charge of 3 by vertical displacement of the deposition cell.The deposition technology developed here using Laguerre-Gaussian beam will contribute to advancements in the fabrication of photonic and nano-fluidic devices.

Electrophoretically deposited binder-free 3-D carbon/sulfur nanocomposite cathode for high-performance Li–S batteries

In the present study,the electrophoretic deposition method was successfully applied as a binder-free and scalable approach to deposit carbonaceous nanomaterials on carbon fiber paper(CFP)for cathode applications in Li-S batteries.The microstructural studies of the EPD-CNT film using scanning electron microscopy(SEM)revealed the formation of a crack-free and porous layer of CNTs being uniformly distributed on the CFP surface.The EPD:CFP/CNT/S cathode delivered a capacity around 2.2 times higher than that obtained in the absence of the EPD-CNT film(CFP/S cell)after 50 cycles and a capacity of935 mAh g^-1 after 100 cycles at 0.1 C.The EPD method was then employed to fabricate layer-by-layer structures where the EPD-CNT film was decorated with carbon black particles.The initial capacity as well as the reversible capacity after 100 cycles was further increased by the EPD:CFP/CNT/KB/S layer-by-layer structure to 1473 and 1033 mAh g^-1,respectively,indicating effective suppression of the shuttle effect.In addition,the rate performance of CFP/S was improved by depositing the EPD-CNT and EPD-CNT/carbon black architectures on CFP surface,and even further enhanced through the co-deposition of CNT and Pt nanoparticles by EPD,delivering a specific capacity of around 730 mAh g^-1 at 1 C.Finally,the cathodes fabricated by EPD were observed to outperform those made by the conventional casting method in terms of cycling performance,internal resistance,and polarization.This difference was ascribed to the non-uniform microstructure of the Cast-CNT film,which resulted in poor interfacial connection between the CNT agglomerates,hindering uniform sulfide/sulfur deposition during cycling.The obtained results suggested that the binder-free C/S nanocomposite cathode made by EPD is key to further enhance the specific capacity and energy density of Li-S batteries.

Fabrication of Porous Nanocrystalline NiCo_2O_4 Electrode for Water Electrolysis

A porous nanocrystalline NiCo_2O_4 compound electrode was obtained.The morphology of the electrode was controlled by altering the concentration of precipitant (NaOH solution).The electrode was consisted of metal substrate (Ni) and porous nanocrystalline NiCo_2O_4 film which was stacked by homosized and pretty regular hexagonal nanoparticles,with thinner than 50 nm and about 200 nm in diameter.The electrode exhibits good electrochemical properties compared with Ni electrode.

Effect of metal nanoparticle doping concentration on surface morphology and field emission properties of nano-diamond films

Nano-diamond particles are co-deposited on Ti substrates with metal(Ti/Ni) nanoparticles(NPs) by the electrophoretic deposition(EPD) method combined with a furnace annealing at 800℃ under N_(2) atmosphere. Modifications of structural and electron field emission(EFE) properties of the metal-doped films are investigated with different metal NPs concentrations. Our results show that the surface characteristics and EFE performances of the samples are first enhanced and then reduced with metal NPs concentration increasing. Both the Ti-doped and Ni-doped nano-diamond composite films exhibit optimal EFE and microstructural performances when the doping quantity is 5 mg. Remarkably enhanced EFE properties with a low turn-on field of 1.38 V/μm and a high current density of 1.32 mA/cm^(2) at an applied field of 2.94 V/μm are achieved for Ni-doped nano-diamond films, and are superior to those for Ti-doped ones. The enhancement of the EFE properties for the Ti-doped films results from the formation of the TiC-network after annealing. However, the doping of electron-rich Ni NPs and formation of high conductive graphitic phase are considered to be the factor, which results in marvelous EFE properties for these Ni-doped nano-diamond films.

Graphene oxide modified membrane for alleviated ammonia crossover and improved electricity generation in thermally regenerative batteries

Thermally regenerative batteries(TRBs) are promising for harvesting low-grade waste heat into electrical power. However, the ammonia crossover from anode to cathode causes self-discharge and then leads to the decay of capacity. To alleviate the ammonia crossover and improve electricity generation, a stable graphene oxide(GO) modified anion exchange membrane(AEM) was proposed. Compared with the original AEM, the GO modified AEM with a 39.5% lower ammonia permeability induces a 24.3% higher maximal power output and 20.2% higher energy density in TRBs. Together with the visualization result,it was demonstrated the ammonia crossover was effectively alleviated by GO modifying the AEM not at a cost of the reduced battery performance, indicating the promising application in future TRBs.

Enhancement in boiling heat transfer performance using reduced graphene oxide coating with controllable components and porous structures

Enhancement in boiling heat transfer performance is significant for addressing thermal management bottlenecks of advanced electronic systems.Reduced graphene oxides(rGO)are regarded as promising candidates for thermal management due to their excellent thermal properties,chemical stability and adjustable wettability.In this study,rGO coatings with micron pores and controllable oxygen contents are prepared on Al substrate via cathodic electrophoretic deposition and subsequent thermal annealing,leading to enhanced pool boiling performance.The heat transfer coefficient for Al/rGO450is 37.2 kW m-2K-1,which is increased by 112.6%compared with bare Al,also outperformed previously reported Al based substrates.It is assumed that the hydrophilic and aerophobic r GO coatings effectively promote the liquid infiltration and bubble departure during pool boiling process.Importantly,repeatability tests indicate the durable stability of vertically oriented rGO nanosheets.Reverse nonequilibrium molecular dynamics simulation indicates that the interfacial transmission coefficients of Al/rGO increase after thermal annealing,indicative of the enhanced heat transfer performance of heterogeneous interface.Our study opens a new avenue for endowing metal substrates with high pool boiling performance using porous carbon coating nanoengineering strategy with controllable morphology and components.

Two-dimensional Cu-porphyrin nanosheet membranes for nanofiltration

A kind of two-dimensional(2D)metal-organic framework(MOF)material,Cu-meso-tetrakis(4-carboxyphenyl)porphine(Cu-TCPP)nanosheets with wrinkled and flat morphologies are used as building blocks to assemble membranes by vacuum filtration(VF)and electrophoretic deposition(EPD)as energy-efficient nanofiltration(NF)membranes to remove dyes from water.Since the nanosheets with wrinkled structure can provide additional water transport channels,thereby increasing the water permeance,in the premise of a high rejection(>97.0%)for the dye brilliant blue G(BBG)(1.60 nm×1.90 nm),the water permeance of the membrane assembled by the wrinkled nanosheets(~1170 nm)is about 4 times that of the membrane assembled by the flat nanosheets(~530 nm),reaching 16.39 L·m^(−2)·h^(−1)·bar^(−1).Additionally,the use of the relatively flat nanosheets and the membrane preparation method of electrophoretic deposition is more conducive to stack nanosheets orderly and reduce defects.Therefore,the water permeance of the membrane prepared by EPD(~1170 nm)with flat nanosheets is about twice that of the membrane prepared by VF(~530 nm),achieving 9.40 L·m^(−2)·h^(−1)·bar^(−1)with similar rejection(>97.0%)of dye evans blue(EB)(3.10 nm×1.20 nm).Furthermore,these membranes still exhibit good separation performance at high pressure of 0.6 MPa.Nanosheets with diverse structures and various membrane fabrication processes provide new directions for the separation performance optimization of 2D MOF materials for water purification.

Highly conductive,stretchable,durable,skin-conformal dry electrodes based on thermoplastic elastomer-embedded 3D porous graphene for multifunctional wearable bioelectronics

Long-term bioelectric potential recording requires highly reliable wearable dry electrodes.Laser-induced graphene(LIG)dry electrodes on polyimide(PI)films are difficult to conform to the skin due to the non-stretchability and low flexibility of PI films.As a result,high interface impedance and motion artifacts can occur during body movements.Transferring LIG to flexible substrates such as polydimethylsiloxane(PDMS)and Ecoflex allows for stretchability and flexibility.However,the transfer process produces a significant loss of conductivity destroying the structural function and electron conduction properties of the LIG.We found robust physical and chemical bonding effects between LIG and styrene-ethylene-butylene-styrene(SEBS)thermoplastic elastomer substrates and proposed a simple and robust low-conductivity loss transfer technique.Successfully embedded LIG onto SEBS to obtain high stretchability,high flexibility,low conductivity losses.Electrophoretic deposition(EPD)of poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid(PEDOT:PSS)on LIG forms an ultrathin polymer conductive coating.The deposition thickness of the conductive polymer is adjusted by controlling the EPD deposition time to achieve optimal conductivity and chemical stability.SEBS/LIG/PEDOT:PSS(SLPP)dry electrodes have high conductivity(114Ω/Sq),stretchability(300%)and reliability(30%stretch,15,000 cycles),low electrode-skin impedance(14.39 kΩ,10 Hz).The detected biopotential signal has a high signal-to-noise ratio(SNR)of 35.78 dB.Finally,the feasibility of SLPP dry electrodes for long-term biopotential monitoring and biopotential-based human-machine interface control of household appliances was verified.

Influence of structural depth of laser-patterned steel surfaces on the solid lubricity of carbon nanoparticle coatings

Carbon nanoparticle coatings on laser-patterned stainless-steel surfaces present a solid lubrication system where the pattern's recessions act as lubricant-retaining reservoirs.This study investigates the influence of the structural depth of line patterns coated with multi-walled carbon nanotubes(CNTs)and carbon onions(COs)on their respective potential to reduce friction and wear.Direct laser interference patterning(DLIP)with a pulse duration of 12 ps is used to create line patterns with three different structural depths at a periodicity of 3.5μm on AISI 304 steel platelets.Subsequently,electrophoretic deposition(EPD)is applied to form homogeneous carbon nanoparticle coatings on the patterned platelets.Tribological ball-on-disc experiments are conducted on the as-described surfaces with an alumina counter body at a load of 100 mN.The results show that the shallower the coated structure,the lower its coefficient of friction(COF),regardless of the particle type.Thereby,with a minimum of just below 0.20,CNTs reach lower COF values than COs over most of the testing period.The resulting wear tracks are characterized by scanning electron microscopy,transmission electron microscopy,and energy-dispersive X-ray spectroscopy.During friction testing,the CNTs remain in contact,and the immediate proximity,whereas the CO coating is largely removed.Regardless of structural depth,no oxidation occurs on CNT-coated surfaces,whereas minor oxidation is detected on CO-coated wear tracks.

Recent advances on electrochemical methods in fabricating two-dimensional organic-ligand-containing frameworks

Organic-ligand-containing frameworks have drawn considerable attention due to their multifunctional properties as well as tunable structures for broad applications.Among numerous synthesis methods developed in the past two decades,electrochemical processing has been demonstrated as one of the most efficient,safe,and facile ways to realize the large-scale and highly controllable production of organic-ligand-containing frameworks.In this review,the progress of electrochemically induced crystallization and thin film fabrication of organic-ligand-containing frameworks is summarized in a well-rounded way.Besides,the mechanism and processing parameters are also discussed.Moreover,the main challenges are also expounded for providing some guidance on the future development of organic-ligand-containing frameworks,especially for covalent-organic frameworks and hydrogen-bonded organic frameworks.