Water pollution from industrial and household waste presents significant environmental challenges, particularly owing to the widespread use and toxicity of organic dyes such as rhodamine B (RhB). This study investigates the photocatalytic degradation of RhB using composite films composed of zinc oxide (ZnO) and silver nanowires (AgNWs) under ultraviolet (UV) irradiation. ZnO is well known for its strong photocatalytic activity because of its high charge-carrier mobility and ability to generate reactive oxygen species (ROS). However, its relatively large bandgap (approx. 3.3 eV) limits its light absorption primarily to the UV range, restricting its photocatalytic efficiency under visible light. The incorporation of AgNWs is expected to enhance charge separation, increase electron mobility and introduce localized surface plasmon resonance effects, which contribute to improved light absorption and photocatalytic performance. The ZnO/AgNW composite films were synthesized using a sol–gel method and characterized through scanning electron microscopy and energy-dispersive X-ray spectroscopy to analyse the morphology and elemental composition, X-ray diffraction to confirm the crystallinity structure, and UV–visible spectroscopy to determine optical properties and bandgap energy. The bandgap reduction observed in ZnO/AgNW composites, as confirmed by Tauc plot analysis, is attributed to structural modifications, oxygen vacancy formation and plasmonic interactions that enhance charge transfer and light absorption. This enhanced optical response directly contributed to the superior photocatalytic efficiency of the composite. The reduction in bandgap directly influenced the photocatalytic performance of the ZnO/AgNW composites. A lower bandgap extends light absorption into the visible range, allowing the material to use a broader spectrum of incident light. Furthermore, the enhanced charge-carrier separation and increased ROS generation contributed to superior photocatalytic efficiency. As a result, the ZnO/AgNW composite films achieved a 90% degradation efficiency of RhB within 40 min of UV exposure, demonstrating a significant improvement over conventional ZnO-based photocatalysts. These findings highlight the potential of ZnO/AgNW nanocomposites as efficient, reusable and scalable solutions for water purification and environmental remediation applications.

In this paper we report on the improvement of performance by minimizing scallop size through deep reactive-ion etching (DRIE) of rotors in micro-wind turbines based on micro-electro-mechanical systems (MEMS) technology. The surface profile of an MEMS rotor can be controlled by modifying the scallop size of the DRIE surface through changing the process recipe. The fabrication of a planar disk-type MEMS rotor through the MEMS fabrication process was carried out, and for the comparison of the improvements in the performance of each rotor, RPM testing and open circuit output voltage experiments of stators and permanent magnets were performed. We found that the smooth etching profile with a minimized scallop size formed using DRIE results in improved rotation properties in MEMS-based wind turbine rotors.

Phosphorus, an essential rare element in aquatic ecosystems, plays a key role in maintaining ecosystem balance. However, excess phosphorus leads to eutrophication and algal proliferation. To prevent eutrophication, the pretreatment and measuring of the concentration of total phosphorus (TP) is crucial. Compared to conventional TP pretreatment equipment (autoclave), a lab-on-a-chip detection device fabricated using micro-electromechanical system technology and titania (TiO₂) as a photocatalyst is more convenient, efficient, and cost-effective. However, the wide bandgap of TiO₂ (3.2 eV) limits photocatalytic activity. To address this problem, this paper describes the preparation of a TiO₂/Au nanocomposite film using electron-beam evaporation and atomic-layer deposition, based on the introduction of gold film and TiO₂ to a quartz substrate. The photocatalytic degradation properties of TiO₂/Au nanocomposite films with thicknesses of 1, 2, 3, and 4 nm were assessed using rhodamine B as a pollutant. The experimental results demonstrate that the deposition of gold films with different thicknesses can enhance photocatalytic degradation efficiency through synergetic reactions in the charge separation process on the surface. The optimal photocatalytic efficiency is achieved when the deposition thickness is 2 nm, and it decreases with further increase in the thickness. When the photocatalytic reaction time is 15 min, the lab-on-a-chip (LOC) device with a 2-nm-thick gold layer and autoclave exhibits a similar TP pretreatment performance. Therefore, the proposed LOC device based on photocatalytic technology can address the limitations of conventional autoclave equipment, such as large volumes, long processing times, and high costs, thereby satisfying the growing demand for on-site evaluation.

Phosphorus, an essential rare element in aquatic ecosystems, plays a key role in maintaining ecosystem balance. However, an excess of phosphorus will lead to eutrophication and algal pro-liferation. To prevent eutrophication, it is crucial to pretreat and measure the concentration of total phosphorus (TP). Compared with conventional TP pretreatment equipment (autoclave), a lab-on-a-chip detection device fabricated through micro-electromechanical system technology using titania (TiO2) as a photocatalyst is more convenient, efficient, and cost-effective. However, the wide bandgap of TiO2 (3.2 eV) limits the photocatalytic activity. To address this problem, this paper describes the preparation of a TiO2/Au nanocomposite film by electron-beam evaporation and atomic layer deposition, based on the introduction of a gold film and TiO2 on a quartz substrate. The photocatalytic degradation properties of TiO2/Au nanocomposite films with thicknesses of 1, 2, 3, and 4 nm are assessed using rhodamine B as a pollutant. Experimental results demonstrate that the deposition of a gold film with different thicknesses can enhance the photocatalytic degradation efficiency through synergetic reactions in the charge separation process on the surface. The optimal photocatalytic efficiency is achieved when the deposition thickness is 2 nm, and it decreases with further increase in the thickness. When the photocatalytic reaction time is 15 min, the LOC device with a 2-nm-thick gold layer and autoclave exhibit similar TP pretreatment performance. Therefore, the proposed LOC device based on photocatalysis technology can address the limitation of conventional autoclave equipment, such as large volume, long processing time, and high cost, thereby satisfying the growing demand for on-site evaluation.