Surface Modification Process Research Articles

A Novel Flexible Silver Heater Fabricated by a Solution-Based Polyimide Metalization and Inkjet-Printed Carbon Masking Technique

An easy-to-fabricate, high-performance, and ultrabendable heater is always essential for the development of flexible devices such as gas sensors. Currently, most of the flexible heaters involve vacuum facilities or special inkjet printers/inks, which leads to complex processes and high fabrication cost. In this work, an innovative polymeric metalization technique was developed on polyimide substrate: in addition to the tunable electrical properties, Ag thin films obtained through the low-temperature solution-based process, the so-called surface modification and ion exchange (SMIE) process, could provide enhanced interfacial adhesion and mechanical stability. With a carbon ink as a masking layer, generated by a common home-/office-use inkjet printer, more than 400 patterned flexible heaters can be batch-fabricated on an A4 size polyimide conveniently. The results indicate that the heaters exhibit good electrical properties as well as superior bending stabilities. For the heaters with dimension of 1 cm × 1 ...

Flash Surface Treatment of CH3NH3PbI3 Films Using 248 nm KrF Excimer Laser Enhances the Performance of Perovskite Solar Cells

For perovskite solar cells (PSCs), the surface traps of perovskite films have great influence on the charge carrier behavior at the interface of perovskite and charge transport layers. In this investigation, a 248 nm KrF excimer laser with high photon energy and shallow penetration depth is introduced to perform surface modification on the CH3NH3PbI3 film through irradiation for reducing its surface trap density for the first time. A whole excimer laser surface modification (ELSM) process can be completed in few seconds, and the actual interaction time of the excimer laser and perovskite film is only several hundred nanoseconds. After ELSM, the trap density of the CH3NH3PbI3 film decreases from 1.61 × 1016 cm−3 to 5.81 × 1015 cm−3, and the nonradiative recombination is suppressed effectively. As a result, the open‐circuit voltage and the power conversion efficiency (PCE) of CH3NH3PbI3‐based PSCs increase from 1082 ± 27 to 1117 ± 16 mV and from 16.69% ± 0.77% to 18.50% ± 0.65%, respectively, and the PCE of the champion device reaches 19.38%. In addition, the measured larger charge recombination resistance, slower open‐circuit photovoltage decay, and longer charge recombination lifetime confirm the effective suppression effect of ELSM on the charge carrier recombination in PSCs.

Facile development of poly(tetrafluoride ethylene-r-vinylpyrrolidone) modified PVDF membrane with comprehensive antifouling property for highly-efficient challenging oil-in-water emulsions separation

Fouling problems caused by oil and other pollutants is one of the most severe challenges for membranes used for purification of comprehensive oil-in-water emulsions. Poly(tetrafluoride-r-vinylpyrrolidone) (F-VP) with low-adhesive superoleophobicity is a class of novel material for fouling-repellent membrane modification to achieve highly-efficient separation of complex oily wastewater. In this work, the construction of an ultrathin F-VP layer with a controllable thickness of 2 μm supported by polyvinylidene difluoride (PVDF) substrate was achieved, via an extremely simple, scalable and one-step surface modification process. Benefiting from the ultrathin modification F-VP layer, the resultant F-VP/PVDF membrane exhibited a superior comprehensive fouling-resistant and fouling releasing property, while maintaining a high mass-transfer efficiency without significant permeance sacrificing. The intrinsically non-fouling nature of F-VP modification layer endowed the F-VP/PVDF membrane with superoleophobic property to various oils, superhydrophilic/under oil superhydrophilic properties, and excellent antifouling property for comprehensive oil-in-water emulsions. The F-VP/PVDF membrane has high water permeance of 4612 L m−1 h−1 bar−1, and high emulsion permeance of 461 L m−1 h−1 bar−1 (10000 ppm soybean oil-in-water emulsion) with high rejection ratio of >99.9%, and an outstanding, stable fouling-resistant and fouling-releasing property of ∼93% flux recovery over 5-time continuous cyclic tests. Overall, this work provides an insight into a facile preparation of advanced composite membrane with ultralow fouling-propensity property, which shows great potential in treating practically challenging emulsified wastewater.

Taking LCO to the Next Level: Atomic Layer Deposition for Enhanced Performance of Power Electronics Materials

ALD is a platform technology that has been widely demonstrated throughout the literature to impart significant processing and performance gains on lithium ion battery technologies, having notable impacts on surface stabilization of the positive electrode. At Forge Nano, we have elevated this predominantly research scale technique to production heights, making ALD a viable and affordable technology to meet a variety of materials enhancement needs. Our surface modification process allows for sub-nanometer thickness coatings to be tuned for optimal battery performance for battery chemistries relevant in both power electronics as well as vehicle technologies. In this work we will demonstrate the significant gains observed to commercially available LCO by way of increased cycle life, increased energy density and beyond state-of-the art fast charge capabilities. Alongside performance enhancements, we will explore the mechanisms of ALD protection at high voltage, during shelf-life aging and under strenuous test conditions including variable temperatures and c-rates.

Optical measurement of surface topographies with transparent coatings

Manufacturers nowadays have access to state-of-the-art areal surface topography measurement instruments that allow investigation of surface topography at unprecedented levels of detail and over a wide range of scales. However, high value-added products have demanding requirements, pushing measurement technologies to their limits. Therefore, a deeper insight and more comprehensive understanding of performance and behaviour of current areal surface topography measurement solutions is often needed. In this work, we investigate and compare the results when measuring the same surface with different, state-of-the-art areal surface topography measurement solutions involving the principal optical technologies, notably focus variation microscopy, coherence scanning interferometry, imaging confocal microscopy and point autofocus instrument, operated using different set-ups. The test case is a highly engineered surface obtained through a sequence of mechanical and chemical surface modification processes. The surface has complex topographic formations at micrometre and sub-micrometre scales, and is characterised by the presence of a thin transparent layer, notoriously challenging for optical measurement. The topographies reconstructed from measurement are compared both in terms of visual appearance and texture parameters.

Coupling of synthesis and modification to produce hydrophobic or functionalized nano-silica particles

The processes of synthesis and surface modification were coupled herein to produce hydrophobic or functionalized nano-silica particles. Nano-silica particles with a spherical shape approximately 20 nm in diameter were synthesized. Nano-silica particles with high hydrophobicity were produced by coupling the synthesis with a modification process involving aqueous mixing, spray-drying, and thermal treatment, using the common surfactant sodium dodecyl sulfate (SDS) as a modifier. Amino-functionalized nano-silica particles with high grafting density were produced via the same process using the silane coupling agent γ-aminopropyltriethoxysilane (APTES). The modification was more effective with the coupled process than with the non-coupled process.

Effect of laser-assisted nitriding with a high-power diode laser on surface hardening of aluminum-containing martensitic steel

The surface of steel molds used in injection molding must be particularly hard to withstand abrasive fiber-reinforced plastics. Thus, a laser nitriding process using a gas chamber setup is suggested as a surface modification process for the plastic mold industry in this study. The hardness distributions and microstructural evolution of AISI P21 steel after laser nitriding were fundamentally investigated and compared with the results of laser-assisted selective melting without nitrogen. After laser-assisted selective melting, the hardness had not changed relative to that of the base metal (410 HV), although the martensitic transformation had occurred in the melted zone. On the other hand, the laser-nitrided specimen (at 4500 mm/J of heat input) was approximately 40% (573 HV) harder than the base metal was before laser nitriding. In the region with increased hardness, an area with a high level of nitrogen was observed. In other words, nitrogen successfully penetrated into the surface of the specimen, and it formed a certain layer that corresponded well with the region of increased hardness. Moreover, the microstructure of the nitrogen condensed layer in Al-based nitride (AlN) was characterized by transmission electron microscopy. According to these results, the hardening behavior of AISI P21 steel after laser nitriding was mainly attributed to the development of the AlN phase.

Laser transmission welding and surface modification of graphene film for flexible supercapacitor applications

When a graphene film is coated onto a flexible polymer substrate, weak adhesion can cause delamination of the film under mechanical bending. Moreover, as each graphene layer restacks, the performance of the film as an electrode for a supercapacitor becomes limited. In this study, facile laser welding and surface modification processes are demonstrated to overcome these limitations. First, a continuous wave laser beam is applied to the interface between the coated graphene and the underlying transparent polycarbonate substrate. This welding process significantly improves their adhesion and enables excellent mechanical bendability. Second, surface modification of graphene is achieved under ambient conditions by irradiating the graphene film surface with a nanosecond pulsed laser. Sandwich-type supercapacitors are fabricated using these surface-modified graphene electrodes with a PVA-H3PO4 electrolyte. The effect of the laser fluence on the performance of the supercapacitor is investigated. At an optimal laser power, an areal capacitance of 4.7 mF/cm2 is achieved.

A Facile Process for Surface Modification with Lithium Ion Conducting Material of Li 2 TiF 6 for LiMn 2 O 4 in Lithium Ion Batteries

A Facile Process for Surface Modification with Lithium Ion Conducting Material of Li 2 TiF 6 for LiMn 2 O 4 in Lithium Ion Batteries

Enhanced Performance of MSM UV Photodetectors by Molecular Modification of Gallium Nitride Using Porphyrin Organic Molecules

In this brief, we present a novel surface modification process for gallium nitride (GaN) epitaxial films leading to enhanced ultraviolet (UV) photodetection. The adsorption of a layer of thiol-functionalized porphyrin-based organic molecules on the GaN surface has been carried out. The effect of surface modification was seen in the form of a significant reduction in the surface potential of GaN by ~250 mV and five-fold enhancement in the near-band-edge photoluminescence intensity, both indicating surface passivation of GaN. Consequently, reverse current for Nickel (Ni) Schottky contacts on molecularly modified GaN was decreased by 3 orders of magnitude, in dark at room temperature. Upon illumination by UV light, Ni/molecular layer/GaN interdigitated structures showed considerably improved photodetector (PD) characteristics such as responsivity for the visible-blind spectral region, photo-to-dark current ratio, and UV-to-visible rejection ratio. Such metal-molecular layer semiconductor device structures can be useful for the fabrication of more efficient GaN-based UV PDs, mitigating the adverse effects of electronic surface states in these materials.

A Rapid In-Situ Electrochemical Surface Modification Process for Nanotextured Gold Electrodes.

Due to its unique physical and chemical properties, gold has been widely applied as electrode material for various applications. In recent years, with the increasing requirement on the electrode performance, researchers attempted to involve nanostructures into the electrode through various routes, which demonstrated the performance improvement but still are limited by the process complexity, toxic agents and high cost. In this work, a simple and fast electrochemical surface modification process of gold electrodes was developed. Compared with commonly used nanostructured gold electrode synthesis or modification processes, this In-Situ electrochemical modification process is based on electrochemical migration phenomenon and can be completed in short time (<90 seconds) without using caustic chemicals. It is hypothesized that this high efficiency formation mechanism is based on electrochemical dissolution of cations from and redeposition to the electrode surface. The evolution of nanostructures from nanopores under low current density processing conditions to nanodendrites under high current density conditions was observed.

Duplex and Superduplex Stainless Steels: Microstructure and Property Evolution by Surface Modification Processes

The paper presents an overview of diffusion surface treatments, especially nitriding processes, applied to duplex and superduplex stainless steels in the last five years. Research has been done mainly to investigate different nitriding processes in order to optimize parameters for the most appropriate procedure. The scope has been to improve mechanical and wear resistance without prejudice to the corrosion properties of the duplex and superduplex stainless steels. Our investigation also aimed to understand the effect of the nitriding layer on the precipitation of secondary phases after any heating step.

Thermally Self-Healing Graphene-Nanoplate/Polyurethane Nanocomposites via Diels⁻Alder Reaction through a One-Shot Process.

Thermally self-healing graphene-nanoplate/polyurethane (GNP/PU) nanocomposites were prepared via a bulk in-situ Diels–Alder (DA) reaction. Graphene-nanoplate (GNP) was used as a reinforcement and crosslinking platform by a DA reaction with a furfuryl-based chain extender of polyurethane (PU). Results showed that a DA reaction occurred in GNP during the PU forming cure process. This procedure is simple and solvent free because of the absence of any independent surface modification process. Through the calculation of the interfacial tensions, the conditions of the bulk in-situ DA reaction were determined to ensure that GNP and the furfuryl group can react with each other at the interface during the curing process without a solvent. The prepared composites were characterized in terms of thermal, mechanical, and thermally self-healing properties via the DA reaction. In the PU capable of a DA reaction (DPU), characteristic peaks of DA and retro DA reactions were observed in the Fourier transform infrared (FT-IR) spectroscopy and endothermic peaks of retro DA reactions appeared in differential scanning calorimetry (DSC) thermograms. The DPU showed significantly enhanced physical properties and chemical resistance. The thermally self-healing capability was confirmed at 110 °C via the retro DA reactions. It is inferred that thermally self-healable crosslinked GNP/PU nanocomposites via DA reactions could be prepared in a simple bulk process through the molecular design of a chain extender for the in-situ reaction at the interface.

Eco‐friendly Sensors Developed by Herbal Based Silver Nanoparticles for Electrochemical Detection of Mercury (II) Ion

AbstractIn our study, the single‐use &amp; eco‐friendly electrochemical sensor platform based on herbal silver nanoparticles (AgNPs) was developed for detection of mercury (II) ion (Hg2+). For this purpose, the surface of pencil graphite electrode (PGE) was modified with AgNPs and folic acid (FA), respectively. The concentrations of AgNPs and FA were firstly optimized by differential pulse voltammetry (DPV) to obtain an effective surface modification of PGE. Each step at the surface modification process was characterized by using cyclic voltammetry (CV) and electrochemical impedence spectroscopy (EIS). The limit of detection (LOD) for Hg2+ was estimated and found to be 8.43 μM by CV technique. The sensor presented an excellent selectivity for Hg2+ against to other heavy metal ions such as Ca2+, Cd2+, Cr3+, Cu2+, Mg2+, Ni2+, Pb2+, Zn2+, Co2+ and Mn2+. Moreover, a rapid, selective and sensitive detection of Hg2+ was successfully performed in the samples of tap water within 1 min.

Mussel-Inspired Surface Functionalization of AEM for Simultaneously Improved Monovalent Anion Selectivity and Antibacterial Property.

A facile membrane surface modification process for improving permselectivity and antimicrobial property was proposed. A polydopamine (PDA) coating was firstly fabricated on pristine anion exchange membrane (AEM), followed by in situ reduction of Ag without adding any extra reductant. Finally, 2,5-diaminobenzene sulfonic acid (DSA) was grafted onto PDA layer via Michael addition reaction. The as-prepared AEM exhibited improved permselectivity (from 0.60 to 1.43) and effective inhibition of bacterial growth. In addition, the result of the long-term (90-h continuous electrodialysis) test expressed the excellent durability of the modified layer on membrane surface, because the concentration of Cl− and SO42− in diluted chamber fluctuated ~0.024 and 0.030 mol·L−1 with no distinct decline. The method described in this work makes the full use of multifunctional PDA layer (polymer-like coating, in situ reduction and post-organic reaction), and a rational design of functional AEM was established for better practical application.

Enhanced interphase between thermoplastic matrix and UHMWPE fiber sized with CNT-modified polydopamine coating

The fiber phase, matrix phase, and fiber/matrix interphase are different phases of fiber reinforced polymers (FRPs). FRP property such as mechanical strength is highly dependent on the adhesion level between the fiber and matrix for efficient load transfer. In this study, functionalized multiwalled carbon nanotubes (MWCNT) modified dopamine coating solution is coated on the fiber surface as additional sizing to enhance the interfacial bonding strength between ultra-high-molecular-weight polyethylene (UHMWPE) fiber and thermoplastic matrix (Elium®) which has resin infusion capability. The resultant of transverse fiber bundle tests shows that the polydopamine (PDA) coating of fiber with embedded 0.03% of MWCNT can improve the bonding strength of fiber/matrix about 42.50% compared with that of common composites. In contrast, the addition of carbon nanotubes into Elium® matrix shows a distinctly weaker bonding effect than the interphase between neat PDA coating and UHMWPE fiber. This discrepancy is because of densification of carbon nanotubes (CNT) forest grafted on the fiber surface during the nanocomposite coating process. When being compared to other surface modification process, CNT embedded dopamine surface modification is cost effective and less time consuming and has better performance than the modified matrix with the addition of CNTs.

Surface Modification Process by Electrical Discharge Machining with Tungsten Carbide Powder Mixing in Kerosene Fluid

Electrical discharge machining (EDM) process is widely used to process hard materials in the industry. The process of electrical discharge is changed and called PMEDM when alloy powder is added in the oil dielectric. In the current study, the effect of tungsten carbide alloy powder added in the dielectric on the surface roughness (Ra) and the micro hardness of surface (HV) status of the workpiece SKD61 after machining is investigated. Studies show that the surface roughness and the micro hardness of surface obtained by PMEDM is generally better than that by normal EDM. The method can be applied for improving surface quality such as improving strengthening of molds and machine parts.

Effect of Acidity Levels and Feed Rate on the Porosity of Aerogel Extracted from Rice Husk under Ambient Pressure.

Silica aerogels have attracted tremendous interest due to their high specific surface area and the physical, chemical, and mechanical properties as promising materials for thermal insulation, chemical sensors, and energy storage devices. However, large-scale production of silica aerogels remains a challenge due to costly alkoxide precursors and energy-intensive supercritical drying processes. This paper analyzes the effect of acidity levels and feed rate on the porosity of rice husk aerogels with high specific surface area under ambient pressure. This synthetic approach is cost-effective, eco-friendly, and facilitates recycling. Rice husk ash, which consists of 92% amorphous pure silica, was produced by combustion. A process of solvent exchange and surface modification under ambient pressure at different pH levels was conducted for synthesis of the aerogel. The specific surface area of rice husk aerogel was confirmed as ranging from 385 to 861 m2/g under pH 1 to pH 9 and acid feed rate of 0.5 to 5.0 mL/min. The optimized aerogel had a specific surface area of 861 m2/g, a pore volume of 3.33 cm3/g, and an average pore diameter of 12 nm when synthesized at pH 1 and an acid feed rate of 2.5 mL/min. The aerogel was found to be highly hydrophobic, with a water contact angle of 156° up to about 340 °C.

Effects of doping with yttrium on the hydrogen storage performances of the La2Mg17 alloy surface

A simple method of the magnetron sputtering is applied on the surface modification process of the hydrogen storage alloys. Surface doping of La2Mg17 alloy with yttrium-based coatings is illustrated in the research. Some new intermetallics can be formed on the alloys surface via three steps of magnetron sputtering, surface absorption and heat treatment molding. For the hydrogen storage properties, the reversible capacity and cycle stability of the doped sample are all improved, and the hydrogen desorption activation energy is decreased. On the other hand, the surface conditions during the hydrogen absorption and desorption process are also discussed through the SEM, XRD and XPS analyses.

Nanoseparation of Nanoparticle Mixtures with Similar Surface Structures through a Facile Two-Step Approach

Nanoparticles (NPs) with controlled surface modification have unique properties and broad applications, ranging from biomedicine to catalysis. However, surface modification processes usually genera...