Utilizing low-dimensional structures of oxide semiconductors is a promising approach to fabricate relevant gas sensors by means of potential enhancement in surface-to-volume ratios of their sensing materials. In this work, vertically aligned cupric oxide (CuO) nanorods are successfully synthesized on a transparent glass substrate via seed-mediated hydrothermal synthesis method with the use of a CuO nanoparticle seed layer, which is formed by thermally oxidizing a sputtered Cu metal film. Structural and optical characterization by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy reveals the successful preparation of the CuO nanorods array of the single monoclinic tenorite crystalline phase. From gas sensing measurements for the nitrogen monoxide (NO) gas, the vertically aligned CuO nanorod array is observed to have a highly responsive sensitivity to NO gas at relatively low concentrations and operating temperatures, especially showing a high maximum sensitivity to NO at 200 ℃ and a low NO detection limit of 2 ppm in dry air. These results along with a facile fabrication process demonstrate that the CuO nanorods synthesized on a transparent glass substrate are very promising for low-cost and high-performance NO gas sensors.

In this study, complex admittance as a function of temperature and frequency was measured to analyze the important relaxation properties of lead scandium niobate, which is physically important, although it is not an environmentally friendly electrical and electronic material, including lead. Lead scandium niobate was synthesized by heat treating the solid oxide, and the conductance, susceptance and capacitance were measured as a function of temperature and frequency from the temperature dependence of the RLC circuit. The relaxation characteristics of lead scandium niobate were found to be affected by contributions such as grain size, grain boundary characteristics, space charge, and dipole arrangement. As the temperature rises, the maximum admittance and susceptance increase in one direction, but the resonance frequency decreases below the transition temperature but increases after the phase transition.

In recent years, energy-management studies in buildings have proven useful for energy savings. Typically, during heating and cooling, the energy from a given building is lost through its windows. Generally, to block the entry of ultraviolet (UV) and infrared (IR) rays, thin films of deposited metals or metal oxides are used, and the blocking of UV and IR rays by these thin films depends on the materials deposited on them. Therefore, by controlling the thicknesses and densities of the thin films, improving the transmittance of visible light and the blocking of heat rays such as UV and IR may be possible. Such improvements can be realized not only by changing the two-dimensional thin films but also by altering the zero-dimensional (0-D) nanostructures deposited on the films. In this study, 0-D nanoparticles were synthesized using a sol -gel procedure. The synthesized nanoparticles were deposited as deep coatings on polymer and glass substrates. Through spectral analysis in the UV-visible (vis) region, thin-film layers of deposited zinc oxide nanoparticles blocked >95 % of UV rays. For high transmittance in the visible-light region and low transmittance in the IR and UV regions, hybrid multiple layers of silica nanoparticles, zinc oxide particles, and fluorine-doped tin oxide nanoparticles were formed on glass and polymer substrates. Spectrophotometry in the UV-vis-near-IR regions revealed that the substrates prevented heat loss well. The glass and polymer substrates achieved transmittance values of 80 % in the visible-light region, 50 % to 60 % in the IR region, and 90 % in the UV region.

Urea oxidation reaction (UOR) via electrochemical oxidation process can replace oxygen evolution reaction (OER) for green hydrogen production since UOR has lower thermodynamic potential (0.37 V_RHE) than that of OER (1.23 V_RHE). However, in the case of UOR, 6 electrons are required for the entire UOR. For this reason, the reaction rate is slower than OER, which requires 4 electrons. In addition, it is an important challenge to develop catalysts in which both oxidation reactions (UOR and OER) are active since the active sites of OER and UOR are opposite to each other. We prove that among the NiFe₂O₄ nanoparticles synthesized by the hydrothermal method at various synthesis temperatures, NiFe₂O₄ nanoparticle with properly controlled particle size and crystallinity can actively operate OER and UOR at the same time.

Ceramic oxide layer was formed on the surface of high silicon aluminum alloy by using PEO (plasma electrolytic oxidation) process. The microstructure of the oxide layer was analyzed using scanning electron microscopy (SEM) and x-ray diffraction patterns (XRD). The high silicon aluminum alloy prior to PEO process consists of Al, Si and Al₂Cu phases in XRD analysis, whereas Al₂Cu phase selectively disappeared after PEO treatment. Considerable decrease of relative intensity in most of peaks in XRD results of the high silicon aluminum alloy treated by PEO process was observed. It may be attributed to the formation of amorphous phases after PEO treatment. The corrosion behavior of the high silicon aluminum alloy treated by PEO process was investigated using electrochemical impedance spectroscopy (EIS) and other electrochemical techniques (i.e., open circuit potential and polarization curve). Electroanalytical studies indicated that the high silicon aluminum alloy treated by PEO process shows greater corrosion resistance than that untreated by PEO process.

As the demand for lithium-ion batteries, a key power source in electric vehicles and energy storage systems, continues to increase for achieving global carbon neutrality, there is a growing concern about the environmental impact of disposing of spent batteries. Extensive research is underway to develop efficient recycling methods. While hydrometallurgy and pyrometallurgy methods are commonly used to recover valuable metals from spent cathode materials, they have drawbacks including hazardous waste and complex processes. Hence, alternative recycling methods that are environmentally friendly are being explored. However, recycling spent cathode materials still remains complex and energy-intensive. This study focuses on a novel approach called solid-state synthesis, which aims at regenerating the performance of spent cathode materials. The method offers a simpler process and reduces energy consumption. Optimal heat treatment conditions were identified based on experimental results, contributing to the development of sustainable recycling technologies for lithium-ion batteries.

Photoelectrochemical (PEC) water splitting is one of the promising methods for hydrogen production by solar energy. Iron oxide has been effectively investigated as a photoelectrode material for PEC water splitting due to its intrinsic property such as short minority carrier diffusion length. However, iron oxide has a low PEC efficiency owing to a high recombination rate between photoexcited electrons and holes. In this study, we synthesized nanoporous structured iron oxide by anodization to overcome the drawbacks and to increase surface area. The anodized iron oxide was annealed in Ar atmosphere with different purging times. In conclusion, the highest current density of 0.032 mA/cm² at 1.23 V vs. RHE was obtained with 60 s of pursing for iron oxide(Fe-60), which was 3 times higher in photocurrent density compared to iron oxide annealed with 600 s of pursing(Fe-600). The resistances and donor densities were also evaluated for all the anodized iron oxide by electrochemical impedance spectra and Mott-Schottky plot analysis.

In this study, the surface of Polyetheretherketone (PEEK) disks was modified to have a hydrophilic surface by applying a coating of Polyethylene glycol (PEG), Hyaluronic acid(HA), and Poly-Dopamine(PDA). The investigation aimed to examine whether the coated surfaces showed enhanced bioactivity for orthopedic applications compared to the pure PEEK. The microstructure, surface characteristics, and wettability of PEEK coated with PEG, HA, and PDA were analyzed using scanning electron microscopy(SEM), FT-IR spectrophotometer, Roughness Measurement System, Micro-Vickers, and Contact angle measurement. The mechanical properties were analyzed using a tensile testing machine, while the MTT assay for cell activity was analyzed using a microplate reader to measure optical density. According to the SEM and FT-IR results, the composition and crystal structure of PEG, HA and PDA coated surface were verified. Also, roughness, hardness, and contact angle were all improved in the coating group compared to the pure PEEK. We checked the HepG2 cell proliferation by using MTT assay on 7th days. In MTT assay results, HepG2 cell proliferation was increased with time, at 7 days, cell viability on discs coated with PDA was significantly higher than pure PEEK, PEG, HA coated group. PDA coated PEEK exhibited the highest surface roughness, hardness, contact angle, and cell activity. The mechanical properties were not affected by the presence of the coating.

The structures for road safety are guard rails that protect the cars and passengers. If an accident occurs on the roads after a long period of installation, it may escalate into a major disaster. In order to repair many guard rails, the existing repair method of replacing them with new ones requires enormous financial resources. To solve this problem, the G-SAVE method was developed to repair the guard rail without replacing them. This method removes the rust on the surface of the guard rail and then performs ambient-dip galvanizing coating on it without replacing the new ones. No studies or reports have yet been made on the risk assessment of harmful substances, vehicles for these entire processes. Therefore, this paper focuses on risk assessment using the PHA (Preliminary Hazard Analysis) technique and conducts risk assessment for concept design stage of the coating vehicles.