In this study, a four-inch zinc oxide (ZnO) nanostructure was synthesized using radio frequency (RF) magnetron sputtering to maximize the electrochemical performance of the anode material of a lithium-ion battery. All materials were grown on cleaned p-type silicon (100) wafers with a deposited copper layer inserted at the stage. The chamber of the RF magnetron sputtering system was injected with argon and oxygen gas for the growth of the ZnO films. A hydrogen (H2) reduction process was performed in a plasma enhanced chemical vapor deposition (PECVD) chamber to synthesize the ZnO nanostructure (ZnO NS) through modification of the surface structure of a ZnO film. Field emission scanning electron microscopy and atomic force microscopy were performed to confirm the surface and structural properties of the synthesized ZnO NS, and cyclic voltammetry was used to examine the electrochemical characteristics of the ZnO NS. Based on the Hall measurement, the ZnO NS subjected to H2 reduction had a higher electron mobility and lower resistivity than the ZnO film. The ZnO NS that was subjected to H2 reduction for 5 min and 10 min had average roughness of 3.117 nm and 3.418 nm, respectively.

Carbon nanowalls are used as electrodes for second batteries because of the widest reaction surface area among the carbon-based nanomaterials, but their practical application is limited due to the disadvantages of adhesion and stability to lithium-ion batteries. In this research, titanium, titanium nitride, and chromium layers were used as an interlayer between the copper foil and the carbon nanowalls in order to increase the adhesive force and stability. The interlayer was deposited on the substrate using a radio frequency (RF) magnetron sputtering system with a four-inch Ti, TiN, or Cr target. The carbon nanowalls are then grown on interlayer-coated copper foil using a plasma-enhanced chemical vapor deposition (PECVD) system and used as a charge collector for lithium-ion batteries. The middle layer of each sample was identified using a field emission scanning electron microscope (FE-SEM). Impedance measurement and charge/discharge tests were performed to evaluate the characteristics of a lithium-ion battery. Based on the results of this experiment, it was noticed that the research goal can be achieved by inserting the mentioned intermediate layers, and CNWs synthesized on TiN interlayers present the best capacity retention measurement results, which is critical for the future development of lithium-ion batteries.

Recently, as air pollution and particulate matter worsen, the importance of a platform that can monitor the air environment is emerging. Especially, among air pollutants, nitrogen dioxide (NO2) is a toxic gas that can not only generate secondary particulate matter, but can also derive numerous toxic gases. To detect such NO2 gas at low concentration, we fabricated a GNWs/NiO-WO3/GNWs heterostructure-based gas sensor using microwave plasma-enhanced chemical vapor deposition (MPECVD) and sputter, and we confirmed the NO2 detection characteristics between 10 and 50 ppm at room temperature. The morphology and carbon lattice characteristics of the sensing layer were investigated using field emission scanning electron microscopy (FESEM) and Raman spectroscopy. In the gas detection measurement, the resistance negative change according to the NO2 gas concentration was recorded. Moreover, it reacted even at low concentrations such as 5–7 ppm, and showed excellent recovery characteristics of more than 98%. Furthermore, it also showed a change in which the reactivity decreased with respect to humidity of 33% and 66%.

This paper examines a microconstruction consisting of nickel (Ni)/chromium (Cr) alloy thin-film. The total length of the microconstruction was 28 mm, the width was 0.2 mm, and the height was designed to be 1 μm. A thin-film of Ni/Cr alloy was co-sputtered on a silicon dioxide wafer patterned with photoresist via a RF magnetron sputtering system. The RF power ratios applied to the 4 inch target of Ni and Cr were 300 W:100 W (3:1), 300 W:150 W (2:1), and 150 W:150 W (1:1). The electrical resistance of the manufactured microconstruction was calculated and measured through Hall measurements. The temperature generated by applying 1–10 V to the microconstruction electrode was observed by using an infrared camera, and was summarized using a linear equation according to the power applied to each sample.

Carbon nanowall (CNW) and carbon nanotube (CNT) were prepared as anode materials of lithium-ion batteries. To fabricate a lithium-ion battery, copper (Cu) foil was cleaned using an ultrasonic cleaner in a solvent such as trichloroethylene (TCE) and used as a substrate. CNW and CNT were synthesized on Cu foil using plasma-enhanced chemical vapor deposition (PECVD) and water dispersion, respectively. CNW and CNT were used as anode materials for the lithium-ion battery, while lithium hexafluorophosphate (LiPF6) was used as an electrolyte to fabricate another lithium-ion battery. For the structural analysis of CNW and CNT, field emission scanning electron microscope (FE-SEM) and Raman spectroscopy analysis were performed. The Raman analysis showed that the carbon nanotube in composite material can compensate for the defects of the carbon nanowall. Cyclic voltammetry (CV) was employed for the electrochemical properties of lithium-ion batteries, fabricated by CNW and CNT, respectively. The specific capacity of CNW and CNT were calculated as 62.4 mAh/g and 49.54 mAh/g. The composite material with CNW and CNT having a specific capacity measured at 64.94 mAh/g, delivered the optimal performance.

This study focused on glass-based functional coating films to achieve anti-pollution characteristics and photovoltaic (PV) modules efficiency improvement. Anti-pollution functional coating film was applied on glass substrate made of the same material as the cover glass for PV modules. The film was applied to the PV module’s surface by spray coating method and was subsequently annealed by torching to demonstrate real field application. The number of coating application varied from 1 to 3 times to obtain different thickness of films. Natural drying of the sprayed film was done by 10 min dwelling. In sequence, firing process was performed by torch for 2 min to solidify the sprayed films. For the specimens that completed both coating and annealing processes, characteristics including anti-pollution ability, contact angle, and light transmittance were analyzed. Contact angle was analyzed using a contact-angle analyzer, while light transmittance was analyzed using UV–visible capable of utilizing the integrating sphere. Based on the characteristics analyzed, the manufacturing process of the functional coating film was optimized. If the coating process proposed in this study is applied to PV modules, improvement in anti-pollution characteristics as well as efficiency can be expected.

Carbon is not only a readily available material, but also has appropriate properties through various structural modifications. Carbon nanowalls (CNWs), based on carbon with vertical porous nanostructure, offer broad sensing surface area. Using carbon nanowalls, we demonstrated it function as gas sensing layer in our work. Carbon nanowalls synthesized via plasma enhanced chemical vapor deposition (PECVD) was in form numerous nanoflakes. In addition, various defect on its surface with high D band and low G band in Raman spectra was observed. When ammonia (NH3) and nitrogen dioxide (NO2) that may cause environmental pollution as an analyte gas were adsorbed on carbon nanowalls during exposing to them, difference in electrical resistance over 300 percentage between ammonia and nitrogen dioxide appeared. In various characteristics such as response time, sensitivity, saturation-recovery and selectivity, carbon nanowalls-based gas sensor exhibited better performance in nitrogen dioxide than ammonia. The reason for these performance is that the charge transfer of nitrogen dioxide greater than that of ammonia. In addition, the electron affinities of ammonia and nitrogen dioxide are 0.55 +/- 0.10 and 2.11 +/- 0.18 eV, respectively, which may sufficiently affect the each reaction between two analyte gases. Through this work, we offer several results of the proof-of-concept study for the gas sensor application of carbon nanowalls.

In this study, the characteristics of functional films were investigated according to the number of coatings and their heat treatment times. The functional coating films were deposited on glass substrates made of the same material as the cover glass of photovoltaic (PV) modules. Each film was coated once by brushing with a special silica-based solution, and each heat treatment was done using a hot-air fan for 2 min at 300 °C. The substrates were coated once, twice, and thrice, respectively, and were annealed once, twice, and thrice by drying and cooling alternately. The specimens were then analyzed for their anti-pollution properties, contact angles, light transmittance, and mechanical properties. The anti-pollution function was confirmed through a self-cleaning test, while the contact angle and light transmittance were examined using special equipment. Mechanical properties, including hardness and adhesion, were confirmed using the standard hardness testing method (ASTM D3363) such as those using an H-9H, F, HB, or B-6B pencil (Mitsubishi, Japan) and a standard adhesion testing method (ASTM D3359). It was confirmed that the film coated once yielded a very low contact angle of 8.9° and very good anti-pollution properties. Its adhesion and strength also showed high values of 5B and 9H, respectively.

In this study, we investigated characteristics of tungsten carbide thin film according to carbon and tungsten ratio. Tungsten carbide thin film was co-sputtered on silicon substrate and glass substrates using an RF magnetron sputtering system. To analyze the characteristics according to the composition ratio of the tungsten carbide thin film, the RF powers of carbon/tungsten target were divided into 100 W/100 W, 125 W/75 W, 150 W/50 W, and 175 W/25 W, respectively. Hall measurement and 4 points probes were used to measure electrical properties of the tungsten carbide thin films. Raman and field emission scanning electron microscope (FE-SEM) analysis were performed.

In this study, we suggest a functional coatings to improve the durability and anti-pollution properties of solar cell modules. Anti-pollution functional coating was employed on the glass substrate for the PV module. After coating with a brushing technique on a glass substrate, a hot air fan of approximately 200°C was operated for 2 minutes. Using the method which the coating and annealing process was applied, it was performed 2 ~ 3 times every 5 minute intervals. Samples that completed by all the coating and annealing processes were installed outdoors to conduct the durability testing. In order to investigate the change in durability, characteristics such as light transmittance and contact angle were analyzed. The contact angle confirmed the improved hydrophilic property of glass with the deionized water of 5 μL, resulting in the easy cleaning of the PV module cover glass and light transmittance was surveyed using a UV-visible spectroscopy to analyze changes in its properties according to the outdoor environment.

In this article, chemical-vapor-deposition-(CVD)-based pristine carbon nanowall (PCNW) was modified in oxygen plasma and a hydrothermal reduction system into oxidized carbon nanowall (OCNW) and reduced oxidized carbon nanowall (rOCNW). The solubility behavior of the functional groups formed on the PCNW, OCNW, and rOCNW surfaces in ketone- and alcohol-type organic solvents was demonstrated and investigated. When the surfaces of the samples reacted with acetone and methanol were magnified, OCNW showed very high solubility. This indicated that most of the functional groups existed on the surface of OCNW, and that these functional groups reacted the most with the organic solvents, forming H bonding. The dispersion analysis confirmed that the solubility was induced by the activity in the functional groups bonded with the molecules of acetone and methanol. The X-ray photoelectron spectra showed clear changes in hydroxyl and carbonyl, suggesting that hydroxyl and carbonyl are key groups. The ID/IG ratio in the Raman spectra after the reaction with the organic solvents slightly increased. Local dissociation is expected after absorption by the organic solvents into the weak points where the carbon branches were removed by the oxygen plasma. As in the experiment, the prepared CNW reacted with the organic solvents, which showed different results from the carbon-based materials.

The application of a carbon nanowall (CNW) via transfer is very demanding due to the unusual structure of vertically grown wall-shaped that easily collapses. In addition, direct growth on a device cannot obtain a precision-patterned shape because of the temperature limit of the photoresist (PR). Therefore, in this paper, we demonstrate a new CNW surface micromachining technology capable of direct growth. In order to reduce unexpected damage caused by chemical etching, a physical force was used to etch with the adhesive properties of CNWs that have low adhesion to silicon wafer. To prevent compositing with PR, the CNW was surface modified using oxygen plasma. Since there is a risk of surface-modified CNW (SMCNW) collapse in an ultrasonic treatment, which is a physical force, the CNW was coated with PR. After etching the SMCNW grown on PR uncoated area, PR was lifted off using an acetone solution. The effect on the SMCNW by the lift-off process was investigated. The surface, chemical, and structural properties of PR-removed SMCNW and pristine-SMCNW were compared and showed a minimal difference. Therefore, the CNW surface micromachining technique was considered successful.