Electrostatic Spray Deposition Technique Research Articles

Transparent-to-Brown-Black Patterned Electrochromic Metal-Organic Frameworks.

Metal-organic frameworks (MOFs) exhibit promising electrochromic (EC) performance owing to their porous structure, regular channel, and tunable component characteristics. However, few reports focus on MOF materials with the EC performance of a transparent to brown-black (neutral colored state) change that is more suitable for smart windows. In this work, we proposed a strategy for synthesizing MOF (named Ni-BPY) EC materials and corresponding films fabricated via a low-cost electrostatic spray deposition technique. The obtained film exhibits excellent EC performance with a neutral color change from transparent to brown-black, a large optical modulation of 70% at 430 nm, and a fast response within 10 s. Benefiting from good electrical and chemical stability, the Ni-BPY film can be cycled over 500 times. Notably, the Ni-BPY MOF film also delivers a stepwise-controlled process during the bleached state due to its porous characteristics. In addition, the unique color variation of the Ni-BPY film derives from the redox reaction of the Ni metal node between Ni2+ and Ni3+, which is verified by the in situ potential-dependent Raman and X-ray photoelectron spectroscopy (XPS) measurement. As a proof of application, the patterned Ni-BPY EC films and devices are additionally constructed to demonstrate their potential application in electronic tags and logo displays.

Electrochemical performance and stability of PrO1.833 as an oxygen electrode for solid oxide electrolysis cells

Significant efforts have recently been undertaken to develop highly efficient solid oxide cells for high-temperature steam electrolysis (SOEC). Implementing new materials and microstructures that would improve the performance and durability of this technology remains a major issue. For this purpose, a nano-structured PrO1.833 material coated by the electrostatic spray deposition (ESD) technique was studied as a promising active oxygen electrode for SOEC application. The study was performed considering the PrOx as the functional layer and strontium-doped lanthanum manganite (LSM) as the current collecting layer on a standard half-cell supported by a typical Ni-YSZ cermet, a YSZ electrolyte, and a gadolinium-doped ceria (GDC) barrier layer. The electrochemical characterizations showed promising initial performance at 700 °C in SOEC mode (− 1 A cm−2 at 1.4 V with H2O/H2 = 90 vol%/10 vol%). In addition, a reasonable degradation rate of ∼5.8% kh−1 was obtained at 700 °C within 1000 h of SOEC operation. The structural and elemental evolutions were analyzed with micrometer size resolution all along the functional layer thickness using synchrotron μ-X-ray diffraction and fluorescence. The electrode degradation was primarily attributed to the phase transitions of PrO1.833. In particular, the structural analyses of the sample aged under applied current revealed a small quantity of PrO1.5≤x≤1.7 phase at the GDC/AFL (active functional layer) interface which is expected to be less conductive than PrO1.833, along with PrO1.714 and GDC phases. Finally, additional structural characterizations were performed on samples annealed at different temperatures and dwell times: 700 °C for 1000 h and 800 °C for 700 h, respectively. The results are discussed to provide a better understanding of the stability of the praseodymium oxide.

Humidity Sensor Based-on Quartz Crystal Microbalance of Sprayed Silver Nanoparticles Films

The silver nanoparticles (Ag NPs) film was prepared in this work by the electrostatic spray deposition technique. The Ag NPs film properties were characterized by X-ray diffraction, UV-visible spectrophotometer, Raman spectroscopy, and scanning electron microscope. Then, the Ag NPs film was prepared on a 2 MHz crystal microbalance to fabricate the humidity sensor. The measurement systems are composed of a fabricated sensor, oscillator circuit, and frequency counter. The sensor performances were obtained in terms of the frequency shift of the device at various humidity levels. The conditions of saturated salt solutions following NIST standard were used as humidity values for measurement. It was found that the fabricated device exhibited approximately a frequency shift of 25 Hz in the humidity range of 11-93 %RH. Moreover, the device demonstrated low hysteresis at a value of about 1%RH with a humidity level of 43 %RH.

Nano-Confined Tin Oxide in Carbon Nanotube Electrodes via Electrostatic Spray Deposition for Lithium-Ion Batteries.

The development of novel materials is essential for the next generation of electric vehicles and portable devices. Tin oxide (SnO2), with its relatively high theoretical capacity, has been considered as a promising anode material for applications in energy storage devices. However, the SnO2 anode material suffers from poor conductivity and huge volume expansion during charge/discharge cycles. In this study, we evaluated an approach to control the conductivity and volume change of SnO2 through a controllable and effective method by confining different percentages of SnO2 nanoparticles into carbon nanotubes (CNTs). The binder-free confined SnO2 in CNT composite was deposited via an electrostatic spray deposition technique. The morphology of the synthesized and deposited composite was evaluated by scanning electron microscopy and high-resolution transmission electron spectroscopy. The binder-free 20% confined SnO2 in CNT anode delivered a high reversible capacity of 770.6 mAh g-1. The specific capacity of the anode increased to 1069.7 mAh g-1 after 200 cycles, owing to the electrochemical milling effect. The delivered specific capacity after 200 cycles shows that developed novel anode material is suitable for lithium-ion batteries (LIBs).

Effect of thermal modification on the surface quality of a coating applied to wood via the electrostatic spray deposition technique

The surface properties of thermally modified ash wood with a powder coating were investigated, and the results were compared to the unmodified wood. The wood specimens were sanded with 80 grit sandpaper and then pre-heated at 80 °C for 5 min in an infrared oven. The surface of the unmodified and the modified wood specimens were coated with an epoxy/polyester (1 to 1 ratio) hybrid coating using an electrostatic corona spray gun at the pilot plant established in the laboratory. The coatings on the wood specimens were cured at different curing conditions in an infrared oven, i.e., 120 °C/15 min, 140 °C/10 min, and 160 °C/10 min. The results showed that the thermal modification (TM) of the wood caused a slight decrease in the mechanical performance of the surface system (wood substrate and coating film). For example, the scratch and abrasion resistance of the unmodified specimens at the curing temperature of 120 °C were 3.33 N and 135 revolutions but were 3.12 N and 120 revolutions after the TM. However, the average surface roughness (1.26 mu) and contact angle (60.8°) of the distilled water on the cured coatings on the modified wood were lower than those on the unmodified wood (1.86 mu and 80.8°, respectively).

Stretchable MXene/Thermoplastic Polyurethanes based Strain Sensor Fabricated Using a Combined Electrospinning and Electrostatic Spray Deposition Technique

In this work, a novel flexible electrically resistive-type MXene/Thermoplastic polyurethanes(TPU) based strain sensors was developed by a composite process of electrospinning (ES) and electrostatic spray deposition (ESD). Compared with other deposition processes, the sensing layer prepared by ESD has better adhesion to the ES TPU nanofiber membrane and is not easy to crack during the stretching process, thereby greatly improving the working range of the strain sensor. Furthermore, we obtained the sandwich structure easily by ES on the surface of the sensing layer again. This will help make the stress distribution more uniform during the stretching process and further increase the strain sensing range. The ESD-ES strain sensors were attached on skin to monitor various human motions. The results demonstrate that our ESD-ES strain sensors have wide application prospects in smart wearable device.

Effect of Annealing Temperature on Properties of Tin Oxide Films Prepared by Electrostatic Deposition Technique

Abstract In this work, tin oxide films were prepared by electrostatic spray deposition technique. The effect of post annealing temperature on properties of prepare film was performed. The structural, surface morphology and optical properties of tin oxide films were characterized by X-ray diffraction, field-emission scanning electron microscope, and UV-Visible spectrophotometer. The crystalline size is found to increase with increase the annealing temperature. Moreover, the effect of annealing temperature on physical properties of tin oxide films has been performed

Properties of Manganese Oxide Films Prepared by Electrostatic Deposition Technique

Abstract In this work, the electrostatic spray deposition technique was applied to prepare manganese oxide tin films. The effects of post annealing at various temperatures on the properties of manganese oxide film were studied. The properties of the films were assessed by X-ray photoelectron spectroscopy and field-emission scanning electron microscope. In addition, the electrochemical properties of the manganese oxide films were investigated. It was found that the prepared films could be used for super-capacitive, energy storage devices

Flash light sintered SDC cathodic interlayer for enhanced oxygen reduction reaction in LT-SOFCs

To commercialize solid oxide fuel cells, many methods for reducing the production time of manufacturing a fuel cell membrane-electrode-assembly (MEA) using a non-vacuum process have been studied and still the post-heat treatment process is an issue. This paper discusses an alternative sintering method to replace the conventional thermal sintering step for ceramic thin film fabrication, which is time consuming and costly. We fabricated samarium-doped ceria (SDC) thin films, which has high ionic conductivity and high surface exchange coefficient for oxygen reactions at the cathode side. The films were deposited by chemical solution deposition (CSD) method utilizing electrostatic spray deposition (ESD) technique. Thermal decomposition and crystallization steps are required as a post-heat treatment process to obtain desired material properties. For this purpose, the flash light sintering method is adopted and compared with the conventional thermal sintering process using halogen furnace. With this flash light sintering method, the conventional post-heat treatment process time can be significantly reduced from tens of hours to a few seconds. Scanning electron microscopy, X-ray diffraction, and transmission electron microscopy analyses were carried out for material characterizations. Additionally, electrochemical impedance analysis and current-voltage behavior measurements were conducted. By successful fabrication of SDC cathodic functional layer utilizing flash light irradiation process, the 2-folds of fuel cell performance enhancement was obtained in terms of the peak power density at the measurement temperature of 450 °C.

Design of advanced one-step hydroxyapatite coatings for biomedical applications using the electrostatic spray deposition

Calcium phosphate ceramics (CaP), particularly hydroxyapatite Ca10(PO4)6(OH)2 (HAP), are widely used as surface coatings on top of titanium and its alloys in biomedical applications thanks to their ability to form strong bonds with natural bone tissues. In this paper, the electrostatic spray deposition technique (ESD) by using an organic phosphorus (V) precursor is proposed as an alternative to the widely used plasma-spraying process. This bottom-up approach enables the one-step fabrication of single-phase crystalline HAP coatings with unique morphologies. The microstructure and composition of the deposited CaP layers result from a delicate compromise between the physicochemical properties of the precursor solution and the ESD deposition conditions. An in-depth study of their structural, microstructural, compositional properties and their reactivity with Ti6Al4V is undertaken. It shows that the Ca/P molar ratio and the nature of phases are strongly dependent on hydrolysis and evaporation of the P(V) precursor in the ESD process. Optimized deposition conditions are found by using solvents of low-boiling point, for which the coatings deposited above 325 °C correspond to a well crystalline, nanostructured, and single-phase HAP. Infrared heat treatment of a coating prepared from the one optimized precursor solution promotes nanostructured HAP.

Cell performance enhancement facilitated by mixed ionic and electronic conductor fiber for protonic ceramic fuel cells

This study examines the electrochemical properties of a fibrous composite cathode for protonic ceramic fuel cells (PCFC). Sm0.5Sr0.5CoO3-δ (SSC) fibers having embedded BaCe0.5Zr0.35Y0.15O3-δ (BCZY) particles were fabricated using the electro-spinning process. The BCZY powders were prepared using the conventional citrate-nitrate method. It was subsequently mixed with an SSC solution comprising polyvinylpyrrolidone and aqueous metal nitrate. By electro-spinning the obtained mixture, continuous and longish fibers were obtained, yielding a fiber diameter of 150–200 nm after calcination. The calcined composite nanofibers were deposited via the electrostatic slurry spray deposition technique as a cathode layer on a half-cell comprising NiO and BCZY. According to the results of the single-cell measurement, the fibrous composite cathode exhibited much higher electrochemical properties than a typical nanocomposite cathode over the entire operating temperature range of 550–700 °C. Specifically, the polarization resistance of the fibrous composite cathodes was 0.186 Ω·cm2 at 700 °C, lower than that of a typical nanocomposite cathode. In accordance with the impedance analysis, the maximum power density given by the I–V curve was 642 mW/cm2 at 700 °C, which is regarded as reasonable performance for PCFCs.

Transparent and flexible humidity sensor based on graphene oxide thin films prepared by electrostatic spray deposition technique

In this work, transparent and flexible humidity sensors based on graphene oxide film were prepared using the electrostatic spray deposition technique. Graphene oxide (GO) powder was synthesized using the modified Hummer’s method, which was used as a precursor for thin-film deposition. The properties of GO films were characterized by X-ray diffraction, field-emission scanning electron microscope, Raman spectroscopy, Fourier transform infrared spectroscopy, and UV–Vis spectrophotometer. The effect of substrate temperature on the sensor properties was observed. The impedance of the device exhibited a lower value when increasing the relative humidity level. In addition, the device showed high sensitivity of more than 1117.3, fast response with 5 s, more than 60% optical transparency, and flexible property more than 2000 cycles. In addition, the equivalent circuit models of the devices were evaluated from complex impedance measurements used to explain the sensing mechanisms of the device.

Rationally designed three-dimensional porous NiCo2N@C reticular structure for high-performance Li-ion batteries

Three-dimensional (3D) porous NiCo2N@C composite was deposited on nickel foam substrate through the electrostatic spray deposition (ESD) technique followed by a post-annealing process under ammonia atmosphere. The prepared reticular-structured NiCo2N@C film used as binder-free anode for lithium-ion batteries (LIBs) can exhibit excellent electrochemical performance. It delivers high initial discharge capacity of 1215.8 mAh g−1 at a current density of 1 A g−1 and can reach 1630.9 mAh g−1 after 400 cycles. The electrode also shows a superior rate capability with 955.4 mAh g−1 at 10 A g−1 current density.

High-performance red phosphorus-sulfurized polyacrylonitrile composite by electrostatic spray deposition for lithium-ion batteries

Red phosphorus (RP) is a promising anode in lithium-ion batteries (LIBs) application due to its high theoretical capacity, chemical stability, and low cost. However, poor electrical conductivity and huge volume expansion over cycling limited the actual practical application of RP. In this work, red phosphorus/sulfurized polyacrylonitrile (RP-SPAN) hybrid anode material was synthesized for high-performance LIBs through high-energy ball milling and electrostatic spray deposition technique. SPAN as a conductive agent, not only provides better kinetics but also acts as a sufficient matrix with chemical bonding between SPAN and RP. Binder-free RP-SPAN hybrid anode delivered a highly reversible specific capacity of 1605 mAh g−1 at 100 mAh g−1 and high-rate capability of 696 mAh g−1 at 1 A g−1. The advantages of facile preparation and high electrochemical performance demonstrate that the RP-SPAN hybrid material is a promising alternative anode material for advanced LIBs.

Surface properties of oriented strand board coated by electrostatic dry powder spray deposition technique

Use of electrostatic powder coating technology for wood-based panels has considerably increased in the last decade. In this study, oriented strand boards (OSB; OSB/2 and OSB/3 grades) were coated with powder coatings using an electrostatic corona spray gun. Epoxy/polyester (hybrid:1/1) coating that is suitable for indoor applications was applied to the surface of OSB specimens (150 g/m2) at three different curing temperatures, 120 °C for 15 min, 140 °C for 10 min, and 160 °C for 10 min using the electrostatic corona gun. The surface properties of the OSB specimens, roughness, wettability, scratch resistance, abrasion resistance, and film thickness were determined. The abrasion resistance and scratch resistance of the coated OSB specimens improved with increasing curing temperature from 120 to 160 °C. The highest mechanical surface strength was obtained from the OSB/3 specimens cured in the infrared oven at 160 °C for 10 min, while the lowest strength was found in the OSB/2 specimens cured in the infrared oven at 120 °C for 15 min. The contact angle values of the coated OSB specimens increased with increasing curing time, while the surface roughness decreased. The curing temperature of the electrostatic powder coating may be a useful indicator to users to obtain better surface quality on the substrate.

Rationally Designed Three-Dimensional Porous Nico <sub>2</sub>n@C Reticular Structure for High-Performance Li-Ion Batteries

Three-dimensional (3D) porous NiCo2N@C composite was deposited on nickel foam substrate through the electrostatic spray deposition (ESD) technique followed by a post-annealing process under ammonia atmosphere. The prepared reticular-structured NiCo2N@C film used as binder-free anode for lithium-ion batteries (LIBs) can exhibit excellent electrochemical performance. It delivers high initial discharge capacity of 1215.8 mAh g-1 at a current density of 1 A g-1 and can maintain 1630.9 mAh g-1 after 400 cycles. The electrode also shows a superior rate capability with 955.4 mAh g-1 at 10 A g-1 current density.

Bicontinuous transition metal phosphides/rGO binder-free electrodes: generalized synthesis and excellent cycling stability for sodium storage.

Transition metal phosphides (TMPs) have received considerable attention owing to their great potential in energy conversion and storage technologies. Elaborate design and synthesis of various TMPs with abundant structures in order to meet the requirements of various applications is one of the major goals and challenges of sustainable chemistry. In this work, an electrostatic spray deposition (ESD) approach has been developed and has been demonstrated to be a general strategy to fabricate TMPs for the first time. Various bicontinuous TMPs/carbon nanocomposites can be constructed by this approach. This novel architecture, when applied in energy storage systems, can provide an efficient electron/ion mixed-conducting network, thereby inducing fast electron/ion transfer kinetics and enhancing the structural stability upon long term cycling. As proof of concept application, 3D porous Cu3P/rGO nanocomposites as modeling anodes for Na-ion storage show excellent cycling performance and remarkable rate capacities. The sodium storage mechanism is proposed to be a reversible conversion reaction. The microstructural evolution of the electrodes upon cycling correlates well with the capacity variation. The facile and versatile ESD technique is quite universal and can be further extended to various TMPs. This opens exciting opportunities for the incorporation of TMPs in a variety of new applications.

Ultra-fast fabrication of lanthanum strontium manganese thin films using intense pulsed light irradiation

Commercialization of thin film manufacturing is limited due to the long process time and fabrication cost. To solve these problems, the intense pulsed light sintering method was proposed in this paper. This novel sintering process using xenon lamp irradiation accomplished sintering in milliseconds in ambient air. For evaluation of the sintering effects, wide ranges of irradiation energy densities and substrate temperatures were investigated. The additional thermal energy from bottom-heating results in reducing the required photonic energy density. A flash light sintering process was applied to fabricate a lanthanum strontium manganese (La0.8Sr0.2Mn1O3-δ) perovskite structure used in energy and memory devices. The La0.8Sr0.2Mn1O3-δ thin film was coated by an electrostatic spray deposition (ESD) technique, using chemical deposition. This ESD technique is suitable for the flash light sintering process because a wet chemical method facilitates rapid and low-cost commercial fabrication. After the LSMO thin films were coated, the conventional thermal and flash light sintering processes were conducted, and the properties of the LSMO thin film were evaluated for remnant organics, electrical conductivity, crystallinity, and surface morphology. Flash light sintering delivers a complete sintering process in under 1 s, eliminating the frequent obstacles inherent in thermal sintering.

Comparative study on the efficacy of the UHMWPE surface modification by chemical etching and electrostatic spraying method for drug release by orthopedic implants

Failure of fixation between bone and implant surface due to bacterial infection, is one of the key challenges in total hip arthroplasty. It might lead to poor implant stability and complex revision surgery. Surface modification of an acetabular cup liner for sustained drug delivery is an effective approach to reduce the biofilms associated infection. The aim of the study is to evaluate the influence of different surface modification technique on drug delivery, mechanical and tribological performances of the acetabular cup liner. Solvent-based etching and electrostatic spray deposition technique was individually used to engineer a thin microporous surface layer on ultra-high molecular weight polyethylene (UHMWPE), which is commercially used as acetabular cup liner in total hip implant. Porous surfaces were filled with drug (gentamicin) containing biodegradable polymer (chitosan) through impregnation process and their efficacy was compared in the intended application. The surfaces, modified by both techniques, have shown lower friction coefficient. The higher wear rates were noticed for electrostatic sprayed coating. Both the modified surfaces have shown slight decrease in hardness and elastic modulus, which may be attributed to improper impregnation of polymer inside porous surface. However, after the release of drug, the solvent-based etched surface regains its mechanical and tribological properties, in similar range to the unmodified UHMWPE surface. Both the modified surfaces have shown an impressive drug release profile and in vitro antibacterial efficacy. The drug release duration was more for electrostatic spray modified surface. Hence, these surfaces modified implant parts shown great promise for fighting against post-surgery bacterial infection.

Highly conductive, flexible and functional multi-channel graphene microtube fabricated by electrospray deposition technique

Highly conductive and flexible graphene-based microtubes (μ-GTs) have many potential applications in catalyst supports and wearable electronics. However, there is a lack of effective method to fabricate the high-performance μ-GTs, especially the multi-channel ones. In this work, the electrostatic spray deposition technique was introduced to fabricate the graphene oxide-coated polyester thread from cost-efficient graphene oxide suspensions. After the polyester thread template was removed along with the reduction of graphene oxide by thermal annealing, the multi-channel μ-GT was prepared successfully. Due to the multiple structure of the cross section and the vertically aligned reduced graphene oxide sheets of the tube wall, the multi-channel μ-GT exhibits many excellent properties, such as highly conductive, good flexibility, and functionalization. For example, the electrical conductivity of the multi-channel μ-GT thermally reduced at 1200 °C is about 1.99 × 104 S m−1 at room temperature and can light a LED as a conductive wire. And the electrical conductivity is nearly invariable in either the straight or bent state though a cyclic bending test up to 800 times. In addition, the TiO2/multi-channel μ-GT composite shows strong photocurrent response in which the multi-channel μ-GT provides a super platform due to the high specific surface area. The high-performance μ-GTs obtained by the simple method opens the immense potentials for application in wearable devices.