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Pure nanostructured thin films of nickel stannite (NiSnO3; NSO) semiconducting oxide are synthesized by a simple pulsed spray pyrolysis technique on glass substrates at different deposition temperatures and spray times. XRD recorded patterns exhibit a polycrystalline nature for the deposited films. The Raman spectra provide confirmation of the presence of Sn–O and Ni–O bands. FESEM demonstrates a membrane-like structure with hexagonal pores' formation and different diameter sizes. The NSO energy bandgap is calculated to be 3.72 eV using the absorption spectrum fitting method. The photoluminescence intensities of NSO films were found to fluctuate with the influence of deposited substrate temperature and spray time. The photo-sensing performance was examined by calculating the change in the resistance of the deposited films corresponding to the UV light exposure at room temperature. NSO samples prepared at high substrate temperatures, and long spray times perform the best dynamic photo-response for the UV illumination. [ABSTRACT FROM AUTHOR]

This paper investigated the influence of ultraviolet (UV) illumination on the corrosion behavior of 7A04 aluminum alloy in 3.5% NaCl solutions with various pH values (pH=5.0, 7.0, and 10.0) using weight loss measurement, electrochemical methods, and surface analysis techniques. The research results indicated that the corrosion products of 7A04 alloy in salt solutions with different pH values all exhibited n-type semiconductor properties and could trigger the photovoltaic effect under UV illumination. Simultaneously, UV illumination reduced the compactness of the corrosion products, inhibited the enrichment of copper compounds (Cu2O), and promoted the generation of hydroxyl radicals in the solution. Therefore, UV illumination significantly accelerated the corrosion process of 7A04 alloy, with the overall acceleration effect ranking as follows: alkaline > neutral > acidic. In addition, the corrosion mechanism of 7A04 alloy in the test solutions with and without UV illumination was also discussed in this paper.

In this research, graphene oxide was prepared by Hamers' improved method, then, with the electric arc method, silver nanoparticles enter the graphene oxide environment diluted with deionized water, and a colloid of core-shell,silver-silver oxide is prepared. After the samples were prepared, graphene oxide plates containing silver nanoparticles were fixed on them, and samples with the same concentration and volume were placed under ultraviolet radiation for 0, 30, 60, 120, and 240 minutes, respectively. Then, various spectra are prepared from the samples and their linear and non-linear behavior is studied in two experiments, Z-scan and phase spatial modulation. The results of ultraviolet-visible spectroscopy, infrared Fourier transform, and X-ray diffraction show that the resulting solution contains graphene oxide nanoplates and silver oxide nanoparticles. Investigating the nonlinear optical properties of the samples also shows that the nonlinear refractive index of the samples is of the order of , which by ultraviolet radiation to the samples, their nonlinear refractive index changes slightly, and on the other hand, the diffraction pattern with two peaks is observed in the formed structure.

Sediment re-suspension plays a crucial role in releasing endogenous nitrogen and greenhouse gases in shallow urban waters. However, the impacts of repeated re-suspension and photo-induced processes on migration and transformation from endogenous nitrogen, as well as the emission of greenhouse gases, remain unclear. This study simulated three conditions: re-suspension (Rs), re-suspension combined with ultravioletirradiation (Rs + UV), and ultraviolet irradiation (UV). The findings revealed that both repeated sediment re-suspension and exposure to UV light altered the characteristics of surface sediments. Decrease of convertible nitrogen in sediments, leading to the release of ion-exchangeable nitrogen (IEF-N) into NH4+-N and NO3−-N, influenced greenhouse gas production differently under various conditions. The study observed the highest concentration of dissolved N2O in under UV irradiation, positively correlated with NO2−-N and NO3−-N. Re-suspension increased the turbidity of the overlying water and accelerated nitrification, resulting in the highest NO3−-N concentration and the lowest dissolved N2O concentration. Additionally, in the Rs + UV dissolved N2O maintained the higher concentrations than in Rs, with greatest amount of N conversion in surface sediments, and a 59.45% reduction in IEF-N. The production of N2O during re-suspension was mainly positively correlated with NH4+-N in the overlying water. Therefore, this study suggest that repeated re-suspension and light exposure significantly influence nitrogen migration and transformation processes in sediment, providing a theoretical explanation for the eutrophication of water and greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

[Display omitted] Non-spherical, polymeric colloids serve as building blocks for advanced functional materials. We propose a novel method to produce morphologically controlled, non-spherical particles by generating site-selected, convex structures on polystyrene (PS) particles. It consists of two simple procedures: a monolayer of PS particles is illuminated with UV light and is subsequently immersed in a fluorinated solvent (HFIP). UV irradiation generates site-selected, oxidized domains on PS particles with a different solvent affinity than unoxidized PS, and HFIP immersion preferentially swells the oxidized domains. Such swelling gives rise to site-selected, convex structures on PS particles. By adjusting UV irradiation conditions, including incident and azimuth angles, the oxidized sites, i.e., the swelled portions, can be accurately situated, allowing us to produce various convex shapes, including chiral shapes at desired positions on PS particles. [ABSTRACT FROM AUTHOR]

The present study investigates the synthesis of vertically aligned MnO2 nanowires (NW) decorated with gold (Au) and silver (Ag) nanoparticles (NP) via the glancing angle deposition (GLAD) technique without a need for a catalyst. The cross-sectional field emission scanning electron microscopy (FESEM) image and energy-dispersive X-ray spectroscopy (EDS) confirm the successful adornment of Ag NP and Au NP on the top surface of MnO2 NW. Elemental mapping has verified the presence of manganese (Mn), oxygen (O), silicon (Si), Ag, and Au within the sample. X-ray diffraction (XRD) patterns reveal the polycrystalline growth of the MnO2 film with the preferred orientation. AFM reveals that the surface roughness of Au NP/MnO2 NW is more than Ag NP/MnO2 NW. The measured water contact angles of Au NP/MnO2 NW, Ag NP/MnO2 NW, and MnO2 NW were 125° and 113°, respectively. Ag NP/MnO2 NW showed more hydrophilic properties under UV illumination than Au NP/MnO2 NW owing to the efficient separation of photogenerated electron–hole pairs. Ag NP/MnO2 NW's higher photocatalytic activity than Au NP/MnO2 NW is attributed to the increased light absorption of the Ag NP in the UV region. The overall enhancement after decorating the noble metal NP on MnO2 NW could open new avenues for self-cleaning applications. [ABSTRACT FROM AUTHOR]

In this study, we reported the photocatalytic removal of Rhodamine B dye from aqueous solution by TiO2 polymorph powders under UV light illumination. The work primarily highlights the physico-chemical properties of TiO2 semiconductors. X-ray diffraction (XRD) patterns confirmed the presence of anatase, rutile, and a mixture anatase–rutile phases. The nitrogen gas sorption analysis gives BET surface area with highest value obtained with anatase polymorph (74 m2/g). According to the ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS) study, anatase, rutile, and mixture had band gap energies of 3.35, 2.99, and 3.20 eV, respectively. The photoluminescence and the spin trapping results showed a weaker recombination of photoinduced charge carriers and a highest amount of hydroxyl OH• and superoxide O2−• radicals with anatase polymorph. The effect of the catalyst nature and loading on the photocatalytic degradation of Rhodamine B were investigated. The results demonstrated that the maximum rate of Rhodamine B degradation was 99.4% with anatase, 74.7% for mixture, and 67.3% for rutile after 145 min of UV illumination, under the optimum condition (initial dye concentration = 20 µM, catalyst dose = 0.123 g/L). Electron paramagnetic resonance and trapping experiments of free radical confirmed that singlet oxygen 1O2 and h+ are the main reactive species, while •OH and •O2− had displayed a more moderate effect. [ABSTRACT FROM AUTHOR]

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In the current study, a decahedron-like silver nanostructure (D-AgNs) was successfully created in an aqueous solution in the presence of Polyvinylpyrrolidone (PVP) as a capping agent using the gamma-radiolysis approach without the use of a reducing agent. The synthesized D-AgNs were characterized using various analytical tools such as UV–Vis. spectroscopy, SEM, XRD, HRTEM, EDX and FTIR. UV–Vis. absorption spectra showed considerable surface Plasmon resonance (SPR) bands at 350–600 nm, indicating that colloidal D-AgNs had been successfully synthesized. HRTEM image demonstrates well-dispersed uniformly decahedral shapes that are well separated from each other. The produced nanoparticles were effectively stabilized by PVP through interactions, confirmed by the FTIR anlaysis. The synthesis of D-AgNs using gamma radiation was accomplished, in addition its antimicrobial potential, antibiofilm activity, and the effect of UV rays were assessed. In addition, protein leakage assays and SEM imaging were employed to analyze the antimicrobial reaction's mechanism. A wide variety of bacteria, including S. aureus, P. aeruginosa, and C. albicans, were deactivated by D-AgNs. In the antibiofilm assay, D-AgNs inhibited the biofilm formation of S. aureus (89.58%), E. coli (80.35%), and P. aureginosa (78.45%). After investigating the effect of D-AgNs on the growth curve of S. aureus, we concluded that D-AgNs affect the growth curve of S. aureus, and the curve was reduced to be 0.125. The formation of holes in the S. aureus cell membrane is explained by the fact that the amount of cellular protein released from the bacteria is directly proportional to the concentration of D-AgNs, which was determined to be 259.25 µg/ml at concentration equal to 1.0 mg/mL. [ABSTRACT FROM AUTHOR]

Mini-EUSO is a wide-angle fluorescence telescope that registers ultraviolet (UV) radiation in the nocturnal atmosphere of Earth from the International Space Station. Meteors are among multiple phenomena that manifest themselves not only in the visible range but also in the UV. We present two simple artificial neural networks that allow for recognizing meteor signals in the Mini-EUSO data with high accuracy in terms of a binary classification problem. We expect that similar architectures can be effectively used for signal recognition in other fluorescence telescopes, regardless of the nature of the signal. Due to their simplicity, the networks can be implemented in onboard electronics of future orbital or balloon experiments. [ABSTRACT FROM AUTHOR]

We investigate the effect of pure darkness and UV illumination on the corrosion process of 3Ni weathering steels involved in both marine atmospheric environments. The corrosion behavior of 3Ni steel in both environments was assessed by cyclic acceleration experiments, electrochemical measurements, morphological analysis and physical phase analysis. The results show that UV illumination affects the corrosion process through the photovoltaic effect of the corrosion products, with photoelectrons and photo-vacancies participating in the redox reaction between the substrate and the atmospheric environment, thereby affecting the corrosion rate of 3Ni steel, the physical composition of the corrosion products and the denseness of the rust layer. [ABSTRACT FROM AUTHOR]

This study focuses on the fabrication and characterization of nanostructured zinc oxide films deposited on glass substrates using sol–gel dip-coating methods. The thin films are functionalized with silver ions at various Ag+ concentrations (10−2, 10−3, 10−4 M) through room temperature ion fixation process with and without ultraviolet (UV) illumination. Physicochemical characterization techniques, such as employing Scanning Electron Microscopy with Energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Ultraviolet–Visible Spectroscopy and Electron Paramagnetic Resonance (EPR) techniques. The SEM-EDX and XRD confirmed a characteristic ganglia-like structure with a hexagonal crystalline structure. The photocatalytic performance and available surface area of the pure and Ag films are investigated in the removal of methylene blue dye under UV and visible light illumination and in darkness. It is observed that the photocatalytic activity increases proportionally to the Ag+ ion concentration: ZnO < Ag(10−4 M)/ZnO, < Ag(10−3 M)/ZnO < Ag(10−2 M)/ZnO. Moreover, the catalysts modified under UV illumination during the fixation treatment (Ag-UV/ZnO) exhibited a higher photocatalytic efficiency and degraded the dye in comparison with those without a light source (Ag/ZnO). The experimental results are confirmed using total organic carbon (TOC) analysis. The optimal silver concentration (10−2 M) is established, which shows the highest photocatalytic efficiency (in both cases of ion fixation treatment). The results can be used as a guideline for the development of co-catalyst-functionalized semiconductor photocatalysts. [ABSTRACT FROM AUTHOR]

The porosity of die-cast aluminum alloys is a determining factor for the quality of the product. In this paper, we studied the porosity of a selected part of a die-cast AlSi9Cu3(Fe) compressor part by computer tomography and metallography. In the case of this part, the achievable resolution by CT, a non-destructive testing method, was 30 μm—this method could not detect smaller cavities. Based on metallographic analysis, the percentage of defects larger than 30 μm ranges from 10 to 30% of the total number of defects, which represents 75–95% of the defective area (area ratio). Impregnation with methacrylate resin (used to seal cavities to prevent leakage) can be detected with UV-illuminated optical microscopic examination on metallographically prepared specimens. As confirmed by scanning electron microscopy, partial filling and partial impregnation can occur in a system of shrinkage cavities. [ABSTRACT FROM AUTHOR]

Nickel coatings were fabricated onto the copper substrate by electrodeposition and UV illumination, to obtain long-term stability of the hydrophilic surface. The effect of different fabrication strategies on the surface morphologies was discussed, to reveal the relationship between wettability variation and surface characteristics. The scanning electron microscope, energy-dispersive x-ray spectroscopy, 3D digital microscope and optical contact angle measuring system were adopted to characterize the features of coating surfaces. The results show that the surface morphology, roughness and energy have a significant influence on the variation of surface wettability. The as-prepared coatings were hydrophilic and exhibited high surface free energy. Meanwhile, UV illumination on the virgin coatings led to a slight increase in surface roughness. When exposed to air, the surface with a hemispherical agglomerate structure was more likely to be oxidized and adsorbed airborne organic hydrocarbons, resulting in a significant decrease in surface energy, especially the Lewis acid–base interactions. However, rough surfaces with large pyramid-shaped architecture maintained higher surface energy. After high-temperature aging, the content of carbon elements on the coating surfaces decreased and exhibited better metal lyophilicity. This phenomenon is attributed to organic hydrocarbon particles adsorbed on the surface reacting with the air in a high-temperature environment and then detached from the surface microstructure. This paper provides a method to optimize the surface morphology of nickel coatings on the casting roll, which make the molten metal in a good metal lyophilicity, thus improving the production efficiency of the strip and reducing the production cost. [ABSTRACT FROM AUTHOR]

GaN high-electron-mobility transistors (HEMTs) have attracted widespread attention for high-power microwave applications, owing to their superior properties. However, the charge trapping effect has limitations to its performance. To study the trapping effect on the device large-signal behavior, AlGaN/GaN HEMTs and metal-insulator-semiconductor HEMTs (MIS-HEMTs) were characterized through X-parameter measurements under ultraviolet (UV) illumination. For HEMTs without passivation, the magnitude of the large-signal output wave ( X 21 FB ) and small-signal forward gain ( X 2111 S ) at fundamental frequency increased, whereas the large-signal second harmonic output wave ( X 22 FB ) decreased when the device was exposed to UV light, resulting from the photoconductive effect and suppression of buffer-related trapping. For MIS-HEMTs with SiN passivation, much higher X 21 FB and X 2111 S have been obtained compared with HEMTs. It suggests that better RF power performance can be achieved by removing the surface state. Moreover, the X-parameters of the MIS-HEMT are less dependent on UV light, since the light-induced performance enhancement is offset by excess traps in the SiN layer excited by UV light. The radio frequency (RF) power parameters and signal waveforms were further obtained based on the X-parameter model. The variation of RF current gain and distortion with light was consistent with the measurement results of X-parameters. Therefore, the trap number in the AlGaN surface, GaN buffer, and SiN layer must be minimized for a good large-signal performance of AlGaN/GaN transistors. [ABSTRACT FROM AUTHOR]

This study presents a new nanoporous TiO 2 /SnO 2 heterojunction for NO x gas detection by using a two-step sol-gel process. The unique TiO 2 and SnO 2 nanoheterojunction matrix right on the film surface enables the TiO 2 photocatalyst to absorb minimal UV power (3 μW/cm 2 ) and effectively transfer electrons to the SnO 2 conduction band. The sensor detects NO and NO 2 gases down to 4 ppb (response of 0.6%) and 10 ppb (response of 1.3%) at 1 V at room temperature. It also exhibits a fast recovery time (100 ± 40 s at 500 ppb NO x ), an improved response over a wide relative humidity range (10-60%), and a long lifetime over 30 days. The ultralow UV power required can be easily harvested from sunlight, eliminating the need for UV LEDs. XPS and SEM analyses indicated that the unique nanoporous TiO 2 /SnO 2 structure improves sensing performance, with oxygen vacancies playing a critical role in the NO x gas sensing mechanism. This work demonstrated the highly efficient UV catalyst effect in sensors with the surface heterojunction matrix. The low-power ppb-level NO x detection is suitable for environmental monitoring and respiratory disease detection.

In this research, Co0.5Zn0.5Al2O4 spinel oxides photocatalysts were elaborated from layered double hydroxides Co-Zn-Al/CO3 precursor by calcination at 300, 400, 500, 600, 800, and 1000 °C. XRD, FTIR, TGA/DTA, and SEM/EDX analysis were used for characterized of prepared photocatalysts. The photocatalytic efficiency of the prepared materials was tested by photodegradation of methyl orange (MO) azo dye as a model of textile contaminants under UV illumination. The effect of various operational factors such as irradiation time, initial pH, catalyst dose, methyl orange concentration and reuse were investigated. The enhancement of the photodegradation was strongly dependent on the calcination temperature. A synergic effect between the adsorption and photodegradation was observed. After 50 min of irradiation, the catalyst calcined at 400 °C showed the highest efficiency (98.2%). After regeneration (up to five cycles), the photocatalyst showed high stability.

Antifogging surfaces with unique properties to migrate severe fog formation have gained extensive interest, which is of particular interest for transparent substrates to obtain high visibility and transparency. To date, a large number of strategies including superhydrophilic or superhydrophobic surfaces and titanium dioxide (TiO2)-based composite coatings have been developed based on different mechanisms. Although these surfaces exhibit effective antifogging properties, the rigid nanostructures, cumbersome preparation, and the need for UV light excitation largely limit their widespread applications. Herein, we report a zwitter-wettable antifogging and frost-resisting coating through a fast UV-curable cross-linking of copolymer with benzophenone groups. A series of random copolymers consisting of hydrophilic hydroxyethyl methacrylate (HEA), hydrophobic methyl methacrylate (MMA), and benzophenone-based acrylate units are developed by thermally triggered free-radical polymerization. Upon UV light irradiation, a highly efficient antifogging/frost-resisting coating is covalently bonded on a polycarbonate plate surface, maintaining a light transmission higher than 85%, which was confirmed in both high and low temperature anti-fog tests. Moreover, the wetting behaviors reveal that the antifogging performance exhibited by the zwitter-wettable surface mainly relies on its surface water-adsorbing capability to imbibe condensed water vapor on the surface outmost layer. Notably, the antifogging/frost-resisting behaviors can be well regulated by adjusting the hydrophilic/hydrophobic units, due to the proper balance between the water-adsorption and coating stability. Owing to its simplicity, low-cost preparation and high efficiency, this UV-curable acrylate antifogging coating may find a wide range of applications in various display devices in analytical and detection instruments. [ABSTRACT FROM AUTHOR]

We investigate the effect of pure darkness and UV illumination on the corrosion process of 3Ni weathering steels involved in both marine atmospheric environments. The corrosion behavior of 3Ni steel in both environments was assessed by cyclic acceleration experiments, electrochemical measurements, morphological analysis and physical phase analysis. The results show that UV illumination affects the corrosion process through the photovoltaic effect of the corrosion products, with photoelectrons and photo-vacancies participating in the redox reaction between the substrate and the atmospheric environment, thereby affecting the corrosion rate of 3Ni steel, the physical composition of the corrosion products and the denseness of the rust layer.

This study aimed to explore the synergistic mechanism of lignin chromophore modifications via UV treatment and to analyze the effects of mechanical treatments on LCNF properties for future uses. The procedure involved two steps: first, lignin's chromophore modification via UV illumination, and then the ball milling process was proceeded for 1 h, followed by high-intensity ultrasonic for 15–135 min. Characterization included preserved lignin content percentage, FTIR, UV–vis NMR, and color analysis for UV-modified samples, and to access the influence of mechanical treatment on LCNF samples further yield, zeta potential analysis, XRD, thermogravimetric analysis, atomic force microscopy, and scanning electron microscopy were performed. LCNFs S-120 demonstrated a zeta potential of −21.7 mV, indicating enhanced stability compared to the S-135 sample (−10.95 mV). The S-120 sample also showed the highest yield (74.02 %) and TGA at 391 °C. In XRD analysis, the S-120 sample demonstrated the highest CrI 64.3 %, than the S-15 sample (48.2 %). Preserved lignin in the LCNFs led to a slight reduction in crystallinity across all samples but improved thermal stability for all the prepared LCNFs samples. The UV and ultrasonication improved the homogeneity and durability of the LCNF samples, enabling a process that may be used to industries. [Display omitted] • UV and mechanical processes produce maximum lignin-rich cellulose nanofibrils. • Lignin chromophore modification and ultrasonication's effect on LCNFs were analyzed • LCNFs samples showed good zeta potential and thermal stability. [ABSTRACT FROM AUTHOR]

The wetness impregnation method was used to synthesize 0.1% CdSe/TiO 2 photocatalysts with different atomic molar ratios (90–10, 70–30, 50–50, and 30–70). These catalysts were characterized by XRD, SEM-EDX and mapping, TEM-EDS, UV–VIS spectroscopy, fluorescence spectroscopy, XPS, TPR, TPO, and TPD analyses. Cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) analyses were performed to examine the photocatalytic activity for photocatalytic fuel cells (PFCs) in glucose solution in the dark and under UV illumination. The characterization analyses revealed that anatase TiO 2 formed the catalyst and electronic structure and surface properties changed when doped with metal. The photocatalytic glucose electrooxidation (PGE) results demonstrate that the 0.1% CdSe(50-50)/TiO 2 catalyst has higher photocatalytic activity, stability, and resistance than other catalysts both in the dark (2.71 mA cm−2) and under UV illumination (7.20 mA cm−2). These results offer a promising new type of photocatalyst for PFC applications. • TiO 2 is the most common semiconductor used in photocatalytic applications. • Cd and Se are metals with quantum dot properties. • Wet-impregnation, the most widely used method in catalyst synthesis. • Glucose is an organic material containing high energy in its structure. [ABSTRACT FROM AUTHOR]

Herein we report a one‐step, low cost, photocatalytic method for the synthesis of graphene oxide (GO) from commercial graphite using grey TiO2 as a photocatalyst. GO formation is achieved by UV‐illumination of a slurry of well‐dispersed grey TiO2 and commercial graphite. Light‐induced valence‐band holes from grey TiO2 then lead to an oxidation and exfoliation of graphite, resulting in the formation of visible‐light‐active GO. An optimal level of graphite oxidation can be established by controlling the UV illumination time. Moreover, the resulting GO‐decorated TiO2 is directly active as a visible‐light‐active photocatalyst that can, for example, be used for pollution degradation. [ABSTRACT FROM AUTHOR]

The photocatalytic selective oxidation of propane was investigated by in-situ Fourier transform infrared spectroscopy under the illumination of UV light. Two different commercially available TiO2 photocatalysts were applied; UV-100 and P25. The characterisation data showed significant differences between the two samples; such as phase composition, texture properties, -OH surface density, and the presence of contaminations. P25 (the mixed rutile-anatase phases) showed better adsorption for the reagents and even small quantity of products were observed in dark. However, UV-100; the pure anatase phase with high surface area, exhibited 3–4 times higher photocatalytic activity than P25. Moreover, it was observed that on a similar propane conversion level, the selectivity % of acetone was almost four times higher over P25 than UV-100. Finally, upon mixing UV-100 with rutile, it was observed that the acetone selectivity was improved extensively. [ABSTRACT FROM AUTHOR]

The photocatalytic selective oxidation of propane was investigated by in-situ Fourier transform infrared spectroscopy under the illumination of UV light. Two different commercially available TiO2 photocatalysts were applied; UV-100 and P25. The characterisation data showed significant differences between the two samples; such as phase composition, texture properties, -OH surface density, and the presence of contaminations. P25 (the mixed rutile-anatase phases) showed better adsorption for the reagents and even small quantity of products were observed in dark. However, UV-100; the pure anatase phase with high surface area, exhibited 3–4 times higher photocatalytic activity than P25. Moreover, it was observed that on a similar propane conversion level, the selectivity % of acetone was almost four times higher over P25 than UV-100. Finally, upon mixing UV-100 with rutile, it was observed that the acetone selectivity was improved extensively. [ABSTRACT FROM AUTHOR]

Austenitic stainless steels are commonly used as the base material for dry storage canisters in nuclear power plants because of their excellent corrosion resistance and mechanical properties. Dry storage canisters are often exposed to chloride-containing atmosphere near seashores that could induce localized stress corrosion cracking in these stainless steels near the welded regions. Titanium dioxide (TiO2) coatings applied on stainless steel substrates (i.e. Type 304 L stainless steels) along with ultraviolet irradiation have been proposed as a mitigation measure against corrosion in canister materials. In this study, TiO2 coatings were applied on stainless steel samples using a dip-coating method. The coated samples were then thermally treated under different annealing temperatures. Corrosion behavior and photocatalytic responses of the coated samples with and without UV illumination were evaluated by electrochemical polarization analyses and open circuit potential measurements. Surface morphologies of the samples and the crystal structures were studied by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). It was found that the TiO2 coating not only showed markedly enhanced photocathodic protection on Type 304 L stainless steels during UV illumination but also maintain more active open circuit potentials for several hours after the cutoff of UV illumination. Results from electrochemical polarization analyses further supported the superior corrosion resistance of the coated samples under UV illumination conditions. In addition, the specifically processed TiO2 coatings once irradiated with UV could lead to a prolonged corrosion resistance of the samples even hours without UV illumination.

GaN high-electron-mobility transistors (HEMTs) have attracted widespread attention for high-power microwave applications, owing to their superior properties. However, the charge trapping effect has limitations to its performance. To study the trapping effect on the device large-signal behavior, AlGaN/GaN HEMTs and metal-insulator-semiconductor HEMTs (MIS-HEMTs) were characterized through X-parameter measurements under ultraviolet (UV) illumination. For HEMTs without passivation, the magnitude of the large-signal output wave (X21FB) and small-signal forward gain (X2111S) at fundamental frequency increased, whereas the large-signal second harmonic output wave (X22FB) decreased when the device was exposed to UV light, resulting from the photoconductive effect and suppression of buffer-related trapping. For MIS-HEMTs with SiN passivation, much higher X21FB and X2111S have been obtained compared with HEMTs. It suggests that better RF power performance can be achieved by removing the surface state. Moreover, the X-parameters of the MIS-HEMT are less dependent on UV light, since the light-induced performance enhancement is offset by excess traps in the SiN layer excited by UV light. The radio frequency (RF) power parameters and signal waveforms were further obtained based on the X-parameter model. The variation of RF current gain and distortion with light was consistent with the measurement results of X-parameters. Therefore, the trap number in the AlGaN surface, GaN buffer, and SiN layer must be minimized for a good large-signal performance of AlGaN/GaN transistors.

This work demonstrates that phenylalanine dipeptide-regulated silver can improve the gas sensing performance of a nitrogen dioxide (NO2) gas sensor. Herein, Ag/In2O3 was prepared by a hydrothermal method to detect NO2 gas, where varying amounts of phenylalanine dipeptide (FF) were introduced to regulate the growth of Ag NPs. The morphologies, microstructures, and compositions of the obtained samples were characterized in detail, and the results indicate that Ag NPs grow into nanorods with the regulation of FF. The gas sensing characteristics were systematically investigated with UV illumination (365 nm) at room temperature (25 °C). Upon exposure to NO2 gas, the optimal sensor exhibits a relatively high response value, good linearity, and satisfactory stability. In addition, the sensor can maintain good gas sensing performance under varying humidity. The reason underlying the observed enhancement in the gas sensing property is the formation of more active sites with the Ag nanorod structure. This study suggests that the introduction of polypeptides is a promising idea to improve the performance of gas sensors. [ABSTRACT FROM AUTHOR]

Different loadings of europium were doped into commercial ceria nanoparticles by using europium nitrate solution followed by thermal treatment. The characterisation results showed a formation of Eu2O3 nanoparticles covering the ceria particles; moreover, the density of such cover is increased with europium loading. The photocatalytic performance of the prepared samples was evaluated in the photocatalytic decolourization reaction of methyl green under the illumination of UV black light with an average wavelength of 367 nm. The reaction rate of europium-doped ceria was 4.5–10 times higher compared to the neat ceria sample. [ABSTRACT FROM AUTHOR]

The combination of the photoanode fabrication condition, electrolyte type and light source effect on dye-sensitized solar cell (DSSC) performance were investigated. Three different photoanodes (C1, C2 and C3) were used with different fabrication conditions with two different redox concentration electrolytes (30 and 50 mM) for each photoanode. For these six different combinations, DSSC performances were obtained for 12 different situations using two different light sources, AM 1.5 simulated and ultraviolet (UV-365 nm) illumination. It was obtained that the HI30 electrolyte has higher efficiency for UV illumination and the AN50 electrolyte has higher efficiency for AM1.5 simulated illumination. It was also obtained that the C2 cell with double layer immersed in dye solution has higher efficiency for both two illumination types and two electrolytes. [ABSTRACT FROM AUTHOR]

Controllable wettability is important for a wide range of applications, including intelligent switching, self-cleaning and oil/water separation. In this work, rapid switching and extreme wettability changes upon ultraviolet (UV) illumination were investigated. TiO2 nanoparticles were modified in solutions of trimethoxy(alkyl)silane, and the suspensions were sprayed on glass substrates. For such samples, the water contact angle (WCA) was shown to transition from a superhydrophobic (WCA ≈ 165°) to a superhydrophilic (WCA ≈ 0°) state within 10 min upon UV illumination and subsequent recovery to superhydrophobicity occurred after heat treatment. It was found that the changes in the trimethoxy(alkyl)silane upon UV illumination can explain the rapid decrease of the WCA from more than 165° to almost 0°. To further investigate the wettability transition, trimethoxy(alkyl)silane and Al2O3 nanoparticles (which are not photocatalytic) were mixed and spray-coated onto the glass substrates as the control samples. Then the unrecoverable change of trimethoxy(alkyl)silane under UV illumination can be confirmed. It was found that the presence of trimethoxy(alkyl)silane in the TiO2–trimethoxy(alkyl)silane coating served to speed up the super-wettability transition time from superhydrophobicity to superhydrophilicity, but also limited the number of wettability recycle times. With this understanding, the effect of the trimethoxy(alkyl)silane concentration on the number of recycle cycles was investigated.

We observe enhancements of both conductive and dielectric properties under UV illumination by using a ferroelectric absorber, potassium tantalate niobate (KTa 1-x Nb x O 3 , KTN). The UV-generated electron-hole pairs weaken the intrinsic ferroelectric polarization while enhance the conductive property. The UV-induced heat effect causes the enhancement of the dielectric property. The results are further confirmed by the maximal rectification ratio which shows an opposite trend between the direct heating process and the UV illumination. Our results are useful for better understanding of ferroelectric properties under UV illumination and the development of new optoelectronic devices. [ABSTRACT FROM AUTHOR]

The photoelectrochemical quantification of phenolic compounds such as hydroquinone (HQ) and 4-aminophenol (4-AP) is accomplished by integrating a photoelectrochemical cell into a flow injection analysis (FIA) setup. It is a well-known fact that during the electroanalysis of phenolic compounds, the electrode surface is susceptible to poisoning. However, electrode fouling can be reduced significantly by using the FIA system with periodic washing of the electrode. Reactive oxygen species (ROS), which are generated on the surface of TiO2 under UV light, can oxidize phenolic compounds such as 4-AP. The oxidized form of 4-AP is reduced back at the electrode surface, generating a measurable signal proportional to its concentration. The factors influencing the performance of the sensor, such as flow rate, applied potential for back reduction and pH, are investigated in detail. In the concentration range 0.0125–1.0 µM, a linear correlation between the photocurrent and the concentration of 4-AP was observed with a sensitivity of 0.6 A M−1 cm−2 and a limit of detection of 18 nM. A straightforward analytical methodology for the on-site, highly sensitive and low-cost quantification of phenolic compounds is presented, based on the use of TiO2 in a photoelectrochemical flow cell.

In this work, a wide and highly sensitive chemiresistive sensor has been developed based on the AZO nanocolumn array film. This is meant for the room detection of H 2 O 2 under UV illumination. A cost-effective one step multi-layers growth process was adopted for the synthesis of the AZO nanocolumn array. The experimental studies were done by scanning electron microscopy (SEM), transmission and electron microscopy (TEM).Then X-ray diffraction confirmed that the AZO column array was closely packed, connected, vertically aligned, and polycrystalline, with a high surface area. This structure ensures better electrical conduction over random and separated nanostructures. The hall-effect measurement indicates that the AZO film was n-type, with high conductivity (3.60 × 103 Ωcm), high carrier density (11.3 × 1020cm−3) and with acceptable mobility (0.95 cm2/Vs). The x-ray photoemission spectroscopy suggests that the AZO film consists of a large amount of adsorbed oxygen-related species at the sheath layer of the thin-film, which is vital for sensors. By the UV light activation, sensors based on the AZO nanocolumn array exhibited enhanced H 2 O 2 detection properties at room temperature. At a concentration from 15 μM to 30 mM, H 2 O 2 sensitivity evaluated by relative response was remarkably increased from 15% to 36%. The operation under ambient conditions and wide range sensing shows that this chemiresistive AZO sensor is adequate for biomedical and environmental applications. [ABSTRACT FROM AUTHOR]

Au/n-Si (MS) and Au/Poly (linolenic acid)-g-poly (caprolactone)-g-poly (t-butyl acrylate) (PLilPCLPtBA)/n-Si (MPS) diodes were fabricated to investigate the electrical and responsivity effects of interfacial layer on the diodes under ultra violet (UV) illumination. Electrospinning method was used for coating of the PLilPCLPtBA polymer layer on n-Si single crystal as nanofibers. Surface formation and nanofiber characteristics of the polymer layer were investigated by an electron microscope. The current-voltage (I – V) measurements of the MS and MPS diodes were carried out in dark and under UV (365 nm) illumination conditions at room temperature. Basic electrical parameters of the diodes; such as reverse bias saturation current ( I 0 ), zero bias barrier height (Φ B 0) , ideality factor (n), series resistance ( R s ) and interface state density ( N ss ) were extracted from the experimental I – V measurements by thermionic emission and Norde equations. Also, power law of the photocurrents ( I pc ) and responsivity (R) behavior were obtained and given comparatively. [ABSTRACT FROM AUTHOR]

Chemiresistive gas sensors have been extensively explored for hazardous gas detection. Currently, an overwheming majority of previous attention was focused on the parameter improvement of sensor performance while the impact of carrier gas species on the performance was severely ignored. Aiming to a deep insight into this issue, in this work we prepared zinc oxide (ZnO) nanowire-network sensor and explored its UV-activated sensing performance toward trace nitrogen dioxide gas (NO 2) at room temperature (25 °C) under two carrier gases, i.e., dry nitrogen (N 2) and air. Within N 2 , the sensor exhibited a reversible response of 157 toward 50 ppb NO 2 and a sensitivity of 7.8/ppb, which was not only among the best showcases of the existing work, but much larger than those within air (11 and 0.091/ppb, respectively). Moreover, decent selectivity and long-term stability were demonstrated. Far more UV irradiation-induced electrons which reacted with adsorbed NO 2 molecules on ZnO surface as well as smaller baseline resistance under N 2 than those under air jointly led to the superior response and sensitivity. After long-time UV exposure prior to gas-sensing tests within both carrier gas cases, the remaining oxygen ions (O 2 −) were weakly bonded on ZnO surface, contributing to the reversible behaviors at room temperature. The interconversion between physisorbed O 2 molecules and ionic O 2 − on ZnO surface was proposed to rationalize the sensing phenomena especially when no continuous oxygen was supplied under N 2 atmosphere, which enriched the current transduction mechanisms. [ABSTRACT FROM AUTHOR]

Ni2+-doped ZnO thin films were prepared for various Ni concentration on the porous silicon substrates. The residual stress in the ZnO thin film is relaxed with increase in the concentration of Ni. FESEM images show the growth of pillar-like nanostructures over the entire porous silicon substrates. The variation of resistivity due to UV illumination was observed for the Ni-doped ZnO thin films. Ideality factor value is less for the ZnO:Ni|PS hetero-junction diode than ZnO|PS hetero-junction, Ni doping in ZnO improves the rectifying behavior. [ABSTRACT FROM AUTHOR]

Photocorrosion of a photocatalyst's surface, leading to degradation of its catalytic efficiency/cyclability, is a major concern which must be tackled for designing efficient processes. Despite that the photocorrosion of ZnO has been widely explored, a deep understanding of the mechanism involved is still elusive. Here, a detailed investigation of the photocorrosion mechanism is presented. Controlled UV treatment of ZnO dispersions took place in the absence of pollutants. Employing advanced characterization techniques, we have elucidated the intricate pathways through which the photocorrosion takes place. Successive photocatalytic MB degradation cycles were performed using untreated ZnO nanocrystals to assess their photostability and reusability. It is shown that UV treatment up to 4 h, deteriorates the ZnO crystal which in turn diminishes its photocatalytic activity. For prolonged irradiation up to 8 h, an effective regeneration of the ZnO lattice takes place, reverting the photocatalytic activity to pristine levels. Understanding the photocorrosion mechanism could constitute the key in fabricating large-scale reusable photocatalysts that can be regenerated by UV light. [Display omitted] • Internal and external photocorrosion mechanisms are elucidated. • Prolonged UV treatment in the absence of pollutants leads to catalyst regeneration. • Photocorrosion pathways are explored by advanced surface characterization. • Surface composition determines the photocatalytic rate. [ABSTRACT FROM AUTHOR]

A two-dimensional (2D) Dy2O3-Pd-PDA/rGO heterojunction nanocomposite has been synthesised and tested for hydrogen (H2) gas sensing under various functioning conditions, including different H2 concentrations (50 ppm up to 6000 ppm), relative humidity (up to 25 %RH) and working temperature (up to 200 °C). The material characterisation of Dy2O3-Pd-PDA/rGO nanocomposite performed using various techniques confirms uniform distribution of Pd NPs and 2D Dy2O3 nanostructures on multi-layered porous structure of PDA/rGO nanosheets (NSs) while forming a nanocomposite. Moreover, fundamental hydrogen sensing mechanisms, including the effect of UV illumination and relative humidity (%RH), are investigated. It is observed that the sensing performance is improved as the operating temperature increases from room temperature (RT = 30 °C) to the optimum temperature of 150 °C. The humidity effect investigation revealed a drastic enhancement in sensing parameters as the %RH increased up to 20%. The highest response was found to be 145.2% towards 5000 ppm H2 at 150 °C and 20 %RH under UV illumination (365 nm). This work offers a highly sensitive and selective hydrogen sensor based on a novel 2D nanocomposite using an environmentally friendly and energy-saving synthesis approach, enabling us to detect hydrogen molecules experimentally down to 50 ppm.

Ultraviolet (UV) radiation has been considered a deleterious agent that living organisms must avoid. However, many of the acclimation changes elicited by UV induce a wide range of positive effects in plant physiology through the elicitation of secondary antioxidant metabolites and natural defenses. Therefore, this fact has changed the original UV conception as a germicide and potentially damaging agent, leading to the concept that it is worthy of application in harvested commodities to take advantage of its beneficial responses. Four decades have already passed since postharvest UV radiation applications began to be studied. During this time, UV treatments have been successfully evaluated for different purposes, including the selection of raw materials, the control of postharvest diseases and human pathogens, the elicitation of nutraceutical compounds, the modulation of ripening and senescence, and the induction of cross-stress tolerance. Besides the microbicide use of UV radiation, the effect that has received most attention is the elicitation of bioactive compounds as a defense mechanism. UV treatments have been shown to induce the accumulation of phytochemicals, including ascorbic acid, carotenoids, glucosinolates, and, more frequently, phenolic compounds. The nature and extent of this elicitation have been reported to depend on several factors, including the product type, maturity, cultivar, UV spectral region, dose, intensity, and radiation exposure pattern. Even though in recent years we have greatly increased our understanding of UV technology, some major issues still need to be addressed. These include defining the operational conditions to maximize UV radiation efficacy, reducing treatment times, and ensuring even radiation exposure, especially under realistic processing conditions. This will make UV treatments move beyond their status as an emerging technology and boost their adoption by industry.

Selective and sensitive detection of volatile organic compounds (VOCs) holds paramount importance in real-world applications. This study proposes an innovative approach utilizing a single ReS 2 field-effect transistor (FET) characterized by distinct in-plane anisotropy, specifically tailored for VOC recognition. The unique responses of ReS 2 , endowed with robust in-plane anisotropic properties, demonstrate significant difference along the a -axis and b -axis directions when exposed to four kinds of VOCs: acetone, methanol, ethanol, and IPA. Remarkably, the responses of ReS 2 were significantly magnified under ultraviolet (UV) illumination, particularly in the case of acetone, where the response amplified by 10-15 times and the detection limit decreasing from 70 to 4 ppm compared to the dark conditions. Exploiting the discernible variances in responses along the a -axis and b -axis under both UV and dark conditions, the data points of acetone, ethanol, methanol and IPA gases were clearly separated in the principal component space without any overlap through principal component analysis, indicating that the single ReS 2 FET has a high ability to distinguish various gas species. The exploration of anisotropic sensing materials and light excitation strategies can be applied to a broad range of sensing platforms based on two-dimensional materials for practical applications., (© 2024 IOP Publishing Ltd.)

Nanocarbon materials have the advantages of biocompatibility, thermal stability and chemical stability and have shown excellent electrical properties in electronic devices. In this study, Al/MWCNT:GQD/ITO memristors with rewritable nonvolatile properties were prepared based on composites consisting of multiwalled carbon nanotubes (MWCNTs) and graphene quantum dots (GQDs). The switching current ratio of such a device can be tuned in two ways. Due to the ultraviolet light sensitivity of GQDs, when the dielectric material is illuminated by ultraviolet light, the charge capture ability of the GQDs decreases with an increasing duration of illumination, and the switching current ratio of the device also decreases with an increasing illumination duration (103–10). By exploiting the charge capture characteristics of GQDs, the trap capture level can be increased by increasing the content of GQDs in the dielectric layer. The switching current ratio of the device increases with increasing GQD content (10–103). The device can be programmed and erased more than 100 times; the programmable switching state can withstand 105 read pulses, and the retention time is more than 104 s. This memristor has a simple structure, low power consumption, and enormous application potential for data storage, artificial intelligence, image processing, artificial neural networks, and other applications.