Ultraviolet Irradiation Research Articles

Efficient reductive recovery of arsenic from acidic wastewater by a UV/dithionite process

The removal of arsenic (As(III)) from acidic wastewater using neutralization or sulfide precipitation generates substantial arsenic-containing hazardous solid waste, posing significant environmental challenges. This study proposed an advanced ultraviolet (UV)/dithionite reduction method to recover As(III) in the form of valuable elemental arsenic (As(0)) from acidic wastewater, thereby avoiding hazardous waste production. The results showed that more than 99.9 % of As(III) was reduced to As(0) with the residual concentration of arsenic below 25.0 μg L−1 within several minutes when the dithionite/As(III) molar ratio exceeded 1.5:1 and the pH was below 4.0. The content of As(0) in precipitate reached 99.70 wt%, achieving the purity requirements for commercial As(0) products. Mechanistic investigations revealed that SO2·‒ and H· radicals generated by dithionite photolysis under UV irradiation are responsible for reducing As(III) to As(0). Dissolved O2, Fe(III), Fe(II), Mn(II), dissolved organic matter (DOM), and turbidity slightly inhibited As(III) reduction via free radicals scavenging or light blocking effect, whereas other coexisting ions, such as Mg(II), Zn(II), Cd(II), Ni(II), F(−I), and Cl(−I), had limited influence on As(III) reduction. Moreover, the cost of treating real arsenic-containing (250.3 mg L−1) acidic wastewater was estimated to be as low as $0.668 m−3, demonstrating the practical applicability of this method. This work provides a novel method for the reductive recovery of As(III) from acidic wastewater.

A study on the photoisomerization of phenylpropanoids and the differences in their radical scavenging activity using in-situ NMR spectroscopy and on-line radical scavenging activity analysis

Phenylpropanoids are naturally occurring secondary metabolites that exhibit various biological activities such as ultra-violet (UV) light protection and reactive-oxygen species (ROS) scavenging. In this study, we utilized a light-emitting diode (LED) based in-situ UV irradiation nuclear magnetic resonance (NMR) technique to monitor the photoisomerization reactions of these phenylpropanoids under UV irradiation in real-time. Through this approach, we measured the photochemical reaction rates and photostationary state (PSS) ratios of these molecules and observed distinct reaction rate and PSS ratio information depending on the variation of substituent groups in each phenylpropanoid molecule. We also evaluated the radical scavenging activity (RSA) for each photochemical product through diphenyl-1-picrylhydrazyl radical (DPPH) assay and 2,2’-azino-bis(3-ethylbenzenthiazoline-6-sulphonic acid) (ABTS) assay. We found that the photoisomerization product of caffeic acid can increase both DPPH and ABTS radical scavenging activities, and confirmed the enhanced ABTS radical scavenging ability of caffeic acid cis-isomer based on the online high-pressure liquid chromatography (HPLC)-ABTS analysis and the PSS ratio information of each isomer.

3D printed UV-sensing optical fiber probes: manufacturing, properties, and performance

UV sensing 3D printed optical fiber hydrogels provide a flexible and precise method of remotely of detecting exposure to UV radiations. The optical fibers were created using digital light processing 3D printing technique with hydrogel composites, including micro-sized photochromic dyes (pink, blue and their combination). When exposed to ultraviolet (UV) radiation, these dyes exhibited specific absorption characteristics, resulting in significant decreases in both reflection and transmittance mode spectra at 560 nm, 620 nm, and 590 nm. Optical fibers of lengths 1, 2, and 3 cm were manufactured in two orientations: vertical and horizontal. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction were utilized to characterize the printed fiber probes. The optical performance of the fibers was tested using customized measurement setups. The reflection and transmission of the printed fibers reduced as the length increased due to optical losses. Reflection and transmisson loss of 20–40% can be observed when the length is increased from 1 to 3 cm. The maximum loss in reflection is observed for pink fiber in the presence of UV irradiation. Also, the type of powder used impacted the response and retraction time, whereas the mixed fiber showed the highest response time of 12–20 s under various conditions. The pink dye added fiber probes shows quick response to UV radiation. An increase in the response time is observed with increasing fiber length. The impact of printing orientation on the transmission and reflectance mode operations of optical fibers was assessed. In addition, the stability of the fiber probes are assesed using a green laser having wavelength 532 nm. This work comprehensively examines the optical properties, manufacturing procedures, and sensing capacities of UV-sensitive photochromic optical fiber sensors.

Tannic acid coated ammonium polyphosphate: For flame retardant and UV resistant of polypropylene

Polypropylene (PP) has the advantages of excellent mechanical properties and easy molding, but its shortcomings such as high flammability and poor ultraviolet (UV) resistance cannot be ignored. In this paper, APP was used as the core, 1, 10-diamino-decane (DA) was used as a "bridge" to connect TA to the surface of APP, obtaining TAPP through oxidation self-polymerization. The addition of TAPP greatly improved the flame retardancy and UV resistance of PP matrix. The limiting oxygen index of the PP/22.5 %TAPP sample was increased to 31.0 %, and it was able to pass the UL-94 V-0 rating without droplet produced. Compared with PP samples, the peak heat release rate and peak smoke release rate of PP/22.5 %TAPP sample were reduced by 65.0 % and 44.7 %, respectively. In addition, the tensile strength and impact strength of PP/22.5 %TAPP samples decreased by only 2.7 % and 15.0 % after 60 h UV irradiation. The results showed that the addition of TAPP effectively improved the flame retardancy and UV aging resistance of PP. This study provides a feasible method for the preparation of anti-UV aging and flame-retardant PP composites.

In Situ Photoreversible Tuning of Chemical Interface Damping in Single Gold Nanorods Through Cucurbit[8]uril-Based Host-Guest Interactions.

Chemical interface damping (CID) is a recently proposed plasmon-damping pathway based on the interfacial hot-electron transfer from metal to adsorbate molecules. However, the in situ reversible tuning of CID in single gold nanorods (AuNRs) has remained a considerable challenge. In this study, we used total internal reflection scattering microscopy and spectroscopy to investigate the CID induced by p-aminoazobenzene (p-AAB), which has fast photoisomerization characteristics, attached to single AuNRs. We demonstrated the in situ reversible tuning of CID in single AuNRs by switching between ultraviolet (UV, 365 nm) and visible (vis, 465 nm) irradiation to induce photoresponsive structural conversions between the cis and trans forms of p-AAB in ethanol, leading to different lowest unoccupied molecular orbital (LUMO) energies for both forms. The localized surface plasmon resonance (LSPR) line width was wide under vis irradiation but narrow under UV irradiation, indicating that hot electrons are more efficiently transferred to trans-p-AAB with a low LUMO energy level. We further investigated the in situ photoreversible tuning of CID by manipulating supramolecular host-guest interactions between cucurbit[8]uril (CB[8]) and p-AAB in the single AuNRs. Additionally, real-time in situ reversible tuning of CID in single AuNRs was achieved through photonic switching of the cis-trans forms of p-AAB inside CB[8]. The LSPR line width was narrow under vis irradiation but gradually widened under UV irradiation before narrowing again upon returning to vis irradiation, unlike the case with p-AAB only. These results can be ascribed to the fact that cis-p-AAB completely encapsulated within CB[8] in water is thermodynamically more favorable than trans-p-AAB. Therefore, we have discovered a new strategy for tuning the CID by performing p-AAB photoisomerization and adjusting the wavelength of incident light in single AuNRs. In addition, this study demonstrates that CID can be effectively applied to the development of biosensors to detect guest molecules and their structural changes inside the cavity of CB[8] in single AuNRs.

Room-temperature solution processed silicon nanocluster: Theory prediction and experiment achievement

We have presented in this work that silicon nanoclusters (Si NCs) embedded in silicon nitride (▪) can be synthesized by vacuum ultra-violet irradiation of perhydropolysilazane (PHPS) at room temperature. The formation of Si NCs is first predicted by reactive molecular dynamics (ReaxFF-MD) simulations based on a self-developed Si/N/H force field. Then the existence of Si NCs is further verified by photoluminescence (PL) spectroscopy and Raman spectroscopy characterization. Additionally, the photochemical conversion mechanism of PHPS is examined. Moreover, it has been found based on Fourier transform infrared (FT-IR) measurements that ▪ samples prepared with an intermediate irradiation time are the most readily to be oxidized, which can be attributed to the high concentration of the active group -▪, being consistent with the reaction mechanism. We have demonstrated that ReaxFF-MD simulation can be a powerful complement to experimental investigations in revealing the conversion mechanism of polymer precursor to ceramics at the atomic level.

A high-strength collagen-based antimicrobial film grafted with ε-polylysine fabrication by riboflavin-mediated ultraviolet irradiation for pork preservation

In this study, a UV-cured collagen-based film (C-P-H film) with high mechanical strength and antimicrobial properties was developed by riboflavin-mediated ultraviolet irradiation of collagen solution containing histidine-modified ε-polylysine. Fourier transform infrared analysis indicated that covalent cross-linking was formed between the collagen molecule and the histidine-grafted ε-polylysine. Compared with the pure collagen film, the C-P-H film containing 5 wt% histidine-modified ε-polylysine showed higher tensile strength (145.98 MPa), higher thermal denaturation temperature (76.5 °C), lower water vapor permeability (5.54 × 10−11 g m−1 s−1 Pa) and excellent antimicrobial activities against Escherichia coli and Staphylococcus aureus. In addition, the wrapping of the C-P-H film effectively inhibited bacterial growth of pork during storage time, successfully prolonging the shelf-life of pork by approximately 4 days compared to that of plastic wrap. These results suggested that collagen-based film grafted with histidine-modified ε-polylysine via riboflavin-mediated ultraviolet irradiation process had a great potential for pork preservation.

Photocatalytic nanohybrid UV-light-driven PVDF/GO-NiFe@SiO2 membrane coupled with bentonite adsorption and ozonation process for a sustainable textile wastewater treatment

The textile industries face significant environmental challenges due to the presence of complex pollutant dyes in its wastewater, making it one of the world's major sources of industrial water pollution. Numerous studies have been employed to overcome this problem, including physical, chemical, and biological treatments. However, most of those methods still suffered to achieve higher dye removal performance. This study provides new insight regarding textile wastewater treatment containing indigo red as the main colorant by carrying out a hybrid process combining bentonite adsorption, ozonation, and photocatalytic membrane filtration. For the membrane, we propose a modified polyvinylidene fluoride (PVDF) membrane incorporated with graphene oxide (GO) and nickel-iron doped silica (NiFe@SiO2) photocatalyst, which is named PVDF/GO-NiFe@SiO2 membrane. The membrane was employed under different sets of filtrations (dark and under ultraviolet irradiation) to treat natural dye wastewater from textile industry effluent. Further improvement was achieved when UV light irradiation was subjected to the process. This sequential adsorption-ozonation-membrane process under UV exposure exhibited improved dye removal from 55.11 % to 97.22 %. The results show that the proposed hybrid process successfully improved the membranes' antifouling behavior, thus boosting the membranes' performance and durability. From a broader perspective, our work promotes new insights for the integration of other physical, chemical, and biological treatment methods to improve the performance and durability of membrane-based processes, particularly for dye wastewater treatment.

Morphology-Dependent Photocatalytic Activity of Nanostructured Titanium Dioxide Coatings with Silver Nanoparticles.

This study aims to improve the photocatalytic properties of titanium dioxide nanorods (TNRs) and other related nanostructures (dense nanorods, needle-like nanorods, nanoballs, and nanoflowers) by modifying them with silver nanoparticles (AgNPs). This preparation is carried out using a two-step method: sol-gel dip-coating deposition combined with hydrothermal crystal growth. Further modification with AgNPs was achieved through the photoreduction of Ag+ ions under UV illumination. The investigation explores the impact of different growth factors on the morphological development of TiO2 nanostructures by modulating (i) the chemical composition, the water:acid ratio, (ii) the precursor concentration involved in the hydrothermal process, and (iii) the duration of the hydrothermal reaction. Morphological characteristics, including the length, diameter, and nanorod density of the nanostructures, were analyzed using scanning electron microscope (SEM). The chemical states were determined through use of the X-ray photoelectron spectroscopy (XPS) technique, while phase composition and crystalline structure analysis was performed using the Grazing Incidence X-ray Diffraction (GIXRD) method. The results indicate that various nanostructures (dense nanorods, needle-like nanorods, nanoballs, and nanoflowers) can be obtained by modifying these parameters. The photocatalytic efficiency of these nanostructures and Ag-coated nanostructures was assessed by measuring the degradation of the organic dye rhodamine B (RhB) under both ultraviolet (UV) irradiation and visible light. The results clearly show that UV light causes the RhB solution to lose its color, whereas under visible light RhB changes into rhodamine 110, indicating a successful photocatalytic transformation. The nanoball-like structures' modification with the active metal silver (TNRs 4 Ag) exhibited high photocatalytic efficiency under both ultraviolet (UV) and visible light for different chemical composition parameters. The nanorod structure (TNRs 2 Ag) is more efficient under UV, but under visible-light photocatalyst, the TNRs 6 Ag (dense nanorods) sample is more effective.

Synthesis of Z-scheme amorphous WO3-loaded TiO2 photocatalyst for enhanced photocatalytic degradation of dichloromethane: Internal electric field and mechanism exploration

Photocatalytic technology is a highly efficient means for treatment of volatile organic compounds (VOCs) and mitigation of environmental issues. In this study, we successfully prepared the Z-scheme WO3/TiO2 heterojunction catalyst through the impregnation sintering process. The photocatalytic performance of dichloromethane (DCM) was examined by monitoring its concentration changes under ultraviolet light irradiation. The results demonstrated that 3 % WO3/TiO2 exhibited the most excellent performance, achieving a degradation performance of 98 % under a continuous airflow of 0.8 L/min and an initial DCM concentration of 200 ppm. Importantly, the catalyst maintained its performance without any significant decrease even after 100 h of continuous testing. The excellent performance was mainly thanks to built-in electric field and narrower bandgap, which effectively reduced electron and hole complexation, thereby increasing the production of more reactive oxygen species. Gas phase capture testing revealed that •O2- radicals played a crucial role in DCM degradation. Additionally, the improvement of surface acidity by WO3 and preferential breaking of C-Cl bond effectively prevented the production of phosgene (COCl2). This research finding addresses the gap in the understanding of photocatalytic degradation of DCM with TiO2 modified by metal oxides and lays a strong foundation for future industrial applications.

One-Step Physical and Chemical Dual-Reinforcement with Hydrophobic Drug Delivery in Gelatin Hydrogels for Antibacterial Wound Healing.

Gelatin-based bioadhesives, especially methacrylated gelatin (GelMA), have emerged as superior alternatives to sutureless wound closure. Nowadays, their mechanical improvement and therapeutic delivery, particularly for hydrophobic antibiotics, have received ever-increasing interest. Herein, a reinforced gelatin-based hydrogel with a hydrophobic drug delivery property for skin wound treatment was reported. First, photosensitive monomers of N'-(2-nitrobenzyl)-N-acryloyl glycinamide (NBNAGA) were grafted onto GelMA via Michael addition, namely, GelMA-NBNAGA. Second, gelation of the GelMA-NBNAGA solution was accomplished in a few seconds under one step of ultraviolet (UV) light irradiation. Multiple effects were realized simultaneously, including chemical cross-linking initiated by lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP), physical cross-linking of uncaged dual hydrogen bonding, and hydrophobic drug release along with o-NB group disintegration. The mechanical properties of the dual-reinforcement hydrogels were verified to be superior to those only with a chemical or physical single-cross-linked network. The hydrophobic anticancer doxorubicin (DOX) and antibiotic rifampicin (Rif) were successfully charged into the hydrogels, separately. The in vitro antimicrobial tests confirmed the antibacterial activity of the hydrogels against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. The in vivo wound-healing assessment in mice further assured their drug release and efficacy. Therefore, this NBNAGA-modified GelMA hydrogel has potential as a material in skin wound dressing with a hydrophobic antibiotic on-demand delivery.

Photolytic Degradation of Water‐Soluble Organic Carbon in Snowmelts: Changes in Molecular Characteristics, Brown Carbon Chromophores, and Radiative Effects

AbstractWater‐soluble organic carbon (WSOC) deposited in ambient snowpack play key roles in regional carbon cycle and surface energy budget, but the impacts of photo‐induced processes on its optical and chemical properties are poorly understood yet. In this study, melted samples of the seasonal snow collected from northern Xinjiang, northwestern China, were exposed to ultraviolet (UV) radiation to investigate the photolytic transformations of WSOC. Molecular characteristics and chemical composition of WSOC and its brown carbon (BrC) constituents were investigated using high‐performance liquid chromatography interfaced with a photodiode array detector and a high‐resolution mass spectrometer. Upon illumination, formation of nitrogen‐ and sulfur‐containing species with high molecular weight was observed in snow samples influenced by soil‐ and plant‐derived organics. In contrast, the representative sample collected from remote region showed the lowest molecular diversity and photolytic reactivity among all samples, in which no identified BrC chromophores decomposed upon illumination. Approximately 65% of chromophores in urban samples endured UV irradiation. However, most of BrC composed of phenolic/lignin‐derived compounds and flavonoids disappeared in the illuminated samples containing WSOC from soil‐ and plant‐related sources. Effects of the photochemical degradation of WSOC on the potential modulation of snow albedo were estimated. Apparent half‐lives of WSOC estimated as albedo reduction in 300–400 nm indicated 0.1–0.4 atmospheric equivalent days, which are shorter than typical photolysis half‐lives of ambient biomass smoke aerosol. This study provides new insights into the roles of WSOC in snow photochemistry and snow surface energy balance.

Enhanced TiO2-Based Photocatalytic Volatile Organic Compound Decomposition Combined with Ultrasonic Atomization in the Co-Presence of Carbon Black and Heavy Metal Nanoparticles.

Volatile organic compounds (VOCs) are representative indoor air pollutants that negatively affect the human body owing to their toxicity. One of the most promising methods for VOC removal is photocatalytic degradation using TiO2. In this study, the addition of carbon black (CB) and heavy metal nanoparticles (NPs) was investigated to improve the efficiency of a TiO2-based photocatalytic VOC decomposition system combined with ultrasonic atomization and ultraviolet irradiation, as described previously. The addition of CB and Ag NPs significantly improved the degradation efficiency. A comparison with other heavy metal nanoparticles and their respective roles are discussed.

Influence of Initial Film Properties in UVO-Mediated Patterning of an Elastomeric Film Using a TEM Grid.

Ultraviolet irradiation of a cross-linked polydimethylsiloxane (PDMS) Sylgard 184 film in the presence of atmospheric oxygen (UVO) through a bare transmission electron microscope (TEM) sample holding grid is a rather simple and widely utilized technique for creating micropatterned surfaces. The surface oxidation of a Sylgard 184 film due to UVO exposure is associated with densification and the formation of a silica-like surface layer, which under a TEM grid happens only over the exposed areas of the film, resulting in a physicochemical pattern. It is known that the depth (hD) of the features depends on the duration of UVO exposure (tE). In this article, we show for the first time that hD also depends on the initial film thickness (hF) and the cross-linker percentage (CL, ratio of part A to part B) in a Sylgard 184 thin film. We show that for a specific tE, hD progressively decreases with the reduction in hF. On the other hand, hD shows a nonmonotonic dependence with CL, resulting in patterns with maximum depth for CL ≈ 10.0%. We attribute this observation to the combined effect of resistance against the penetration of the propagation front by the rigid substrate as well as stress relaxation within the exposed parts of the film below the propagating front in films with higher CL values leading to the variation of hD. The observation reported here would allow the potential fabrication of polymer films with physicochemical patterns with feature height on demand by a one-step, facile technique.

Development of Ceria Slurry for Enhanced Chemical Mechanical Polishing (CMP) Performance

As the semiconductor device is shrinking and gets complicated, the chemical mechanical polishing (CMP) process has become important. Various types of abrasive particles are used as CMP slurry, and among them, ceria slurry is in the spotlight due to its high material removal rate (MRR) and selectivity on oxide CMP process. It is known that the ceria abrasives form Ce-O-Si chemical bonds with oxide film, which makes it possible to achieve a high CMP performance.To further advance the performance of ceria slurry, we conducted a series of researches on ceria. A study was conducted on scanning mobility particle sizer (SMPS) measurement to accurately evaluate particle size distribution along with the basic polishing mechanism of monodisperse ceria nanoparticles. In addition, an optimization study was conducted considering the CMP performance according to the abrasive concentration of ceria slurry and the influence of ceria nanoparticles remaining on the wafer surface before the post-CMP cleaning process. Furthermore, research on synthesis method and surface modification of ceria was also conducted to improve the polishing performance. Ce3+ ions on the surface of ceria form Ce-O-Si chemical bond with the silicon dioxide film. Therefore, an important key point is to increase the concentration of Ce3+ ions to improve polishing performance. To achieve high Ce3+ ion concentration, ceria nanoparticles were synthesized through a hydrothermal method, and this performance was improved through lanthanide doping. On the other hand, methods to enhance Ce3+ ion concentration by inducing a reduction reaction on the surface of ceria nanoparticles were also proposed. First, the polishing performance was improved by adding trace metals (FeCl2, CrCl2) to induce a reduction reaction of ceria nanoparticles. Next, the reduction reaction of ceria was induced by applying an eco-friendly method which did not add chemical agents. Ultraviolet (UV) irradiation and hydrogen-gas reduction methods showed sufficient reduction reaction to improve the polishing performance of ceria slurry, and maintained physical properties without causing CMP defects such as poor surface roughness and micro-scratches.As with previous polishing studies, post-CMP cleaning is also important to decease defects. While ceria nanoparticles exhibit great polishing performance for silicon dioxide due to their ability to form chemical bonds, however, they also have the disadvantage of being difficult to remove during the post-CMP cleaning process. To efficiently remove ceria nanoparticles from the wafer surface during the post-CMP cleaning process, various methods have been studied. First, the buff cleaning process was studied in which a deionized water-based cleaning solution is injected instead of slurry after the CMP process. Since the buff cleaning process must simultaneously minimize damage of wafer surface and maximize cleaning performance, optimization research on the properties of the physical factors and cleaning solution is important. For an environmentally friendly cleaning method, we proposed controlling the viscosity of deionized water or using gas-dissolved water. It has been proven that physical factors of cleaning solutions (viscosity, micro bubbles, etc.) can be effective in removing ceria nanoparticles. Especially, hydrogen gas in gas-dissolved water induced a reduction reaction, breaking Ce-O-Si bonds and improving the cleaning performance. Limited to the bulk ceria CMP process, we also studied the improvement of cleaning performance of remained ceria nanoparticles using the tangential flow filtration (TFF) method before CMP process. We focused that small contaminant particles are difficult to remove during the cleaning process, and through the TFF method, small abrasive particles in the slurry are filtered in advance while maintaining the polishing performance.

Enhanced energy density of BOPP film by MAH grafting for metallized capacitors

In this paper, maleic anhydride (MAH) was grafted on the surfaces of biaxially oriented polypropylene (BOPP) film by ultraviolet irradiation treatment to improve the breakdown strength. The addition of MAH, with abundant deep traps, effectively hinders charge injection from the electrode, leading to improved dielectric performance, particularly at elevated temperatures. The experimental results show that the received modified film exhibits an improved permittivity of 2.37 alongside a low dielectric loss of 0.0022 at 1000 Hz. Remarkably, the DC breakdown strength reaches 633.9 kV mm−1, marking a notable 21.4% increase compared to the unmodified BOPP film at 120 °C. Moreover, the film exhibits an energy density of 2.58 J m−3, which is 1.59 times that of the pure film. The charging and discharging efficiency is also greatly improved due to the reduction of conductance losses. Through simulation results, it becomes evident that the enhanced performance is attributed to the alleviation of electric field distortion due to the suppression of injected charge. This work paves a facile route to design scalable polymeric dielectrics with outstanding performance, which facilitates the development of film capacitors.

Layered Heterostructure of Graphene and TiO2 as a Highly Sensitive and Stable Photoassisted NO2 Sensor.

As an atomically thin electric conductor with a low density of highly mobile charge carriers, graphene is a suitable transducer for molecular adsorption. In this study, we demonstrate that the adsorption properties can be significantly enhanced with a laser-deposited TiO2 nanolayer on top of single-layer CVD graphene, whereas the effective charge transfer between the TiO2-adsorbed gas molecules and graphene is retained through the interface. The formation of such a heterostructure with optimally a monolayer thick oxide combined with ultraviolet irradiation (wavelength 365 nm, intensity <1 mW/mm2) dramatically enhances the gas-sensing properties. It provides an outstanding sensitivity for detecting NO2 in the range of a few ppb to a few hundred ppb-s in air, with response times below 30 s at room temperature. The effect of visible light (436 and 546 nm) was much weaker, indicating that the excitations due to light absorption in TiO2 play an essential role, while the characteristics of gas responses imply the involvement of both photoinduced adsorption and desorption. The sensing mechanism was confirmed by theoretical simulations on a NO2@Ti8O16C50 complex under periodic boundary conditions. The proposed sensor structure has significant additional merits, such as relative insensitivity to other polluting gases (CO, SO2, NH3) and air humidity, as well as long-term stability (>2 years) in ambient air. The results pave the way for an emerging class of gas sensor structures based on stacked 2D materials incorporating highly charge-sensitive transducer and selective receptor layers.

Influence of Hydrothermal Temperature on the Physical Characteristics and Photocatalytics Activity of TiO2 for Degradation of Amoxicillin

Titanium dioxide (TiO2) is a photocatalyst material widely used for environmental remediation applications. In this research, TiO2 material was synthesized using the hydrothermal method at various temperatures (150°C, 180°C, and 200°C). Based on the Fourier-transform infrared (FTIR) data, it was found that all the synthesized materials showed similar absorption peaks, and Ti-O-Ti bonds were detected, which is a characteristic of TiO2. X-ray diffraction (XRD) analysis showed that all the synthesized materials were TiO2 anatase with different crystalline sizes. The synthesized TiO2 using the hydrothermal temperature of 180°C showed the smallest crystalline size of 86.81 nm. Based on the analysis of the band gap energy, it was found that wider band gap energy was obtained at higher hydrothermal temperatures. The band gap energies of the synthesized materials are 3.18 eV, 3.19 eV, and 3.21 eV for hydrothermal temperatures of 150°C, 180°C, and 200°C, respectively. The photocatalytic activity of the three synthesized materials was tested in the photodegradation experiment of amoxicillin under ultraviolet (UV) irradiation. As a result, it was found that TiO2 synthesized at 180°C has the highest photocatalytic activity by degrading 100% of amoxicillin compounds within 120 minutes.

Comprehensive Review on the Impact of Chemical Composition, Plasma Treatment, and Vacuum Ultraviolet (VUV) Irradiation on the Electrical Properties of Organosilicate Films.

Organosilicate glass (OSG) films are a critical component in modern electronic devices, with their electrical properties playing a crucial role in device performance. This comprehensive review systematically examines the influence of chemical composition, vacuum ultraviolet (VUV) irradiation, and plasma treatment on the electrical properties of these films. Through an extensive survey of literature and experimental findings, we elucidate the intricate interplay between these factors and the resulting alterations in electrical conductivity, dielectric constant, and breakdown strength of OSG films. Key focus areas include the impact of diverse organic moieties incorporated into the silica matrix, the effects of VUV irradiation on film properties, and the modifications induced by various plasma treatment techniques. Furthermore, the underlying mechanisms governing these phenomena are discussed, shedding light on the complex molecular interactions and structural rearrangements occurring within OSG films under different environmental conditions. It is shown that phonon-assisted electron tunneling between adjacent neutral traps provides a more accurate description of charge transport in OSG low-k materials compared to the previously reported Fowler-Nordheim mechanism. Additionally, the quality of low-k materials significantly influences the behavior of leakage currents. Materials retaining residual porogens or adsorbed water on pore walls show electrical conductivity directly correlated with pore surface area and porosity. Conversely, porogen-free materials, developed by Urbanowicz, exhibit leakage currents that are independent of porosity. This underscores the critical importance of considering internal defects such as oxygen-deficient centers (ODC) or similar entities in understanding the electrical properties of these materials.

Enhancing exciton-to-Mn2+ energy transfer and emission efficiency in Mn2+-doped CsPbCl3 perovskite nanocrystals via CaCl2 post-treatment

Mn2+-doped CsPbCl3 perovskite nanocrystals (NCs) exhibit a significant Stokes shift and emit bright orange-red light, making them promising candidates for optoelectronic devices. However, these NCs are prone to surface defects during multiple purification steps, which hinder the transfer of energy from excitons to Mn2+ and reduce luminescence efficiency. Herein, we introduce a post-treatment method using a CaCl2 ethanol solution to passivate surface defects in Mn2+-doped CsPbCl3 NCs. This treatment enhances the energy transfer from excitons to Mn2+ and boosts luminescence performance, achieving a photoluminescence quantum yield of up to 96 % and maintaining stability through several washing cycles. In this process, Ca2+ ions, as a Lewis acid, replace oleic acid molecules on NC surfaces, leading to stronger binding. The Cl− from the CaCl2 solution fill vacancies on NC surfaces, effectively passivating surface defects. This reduces non-radiative recombination centers, increases energy transfer efficiency from 83 % to 87 %, and accelerates the radiative recombination rates of excitons and Mn2+. The post-treated NCs also retain their PL against continuous heat and ultraviolet irradiation. The passivation of surface defects on perovskite NCs achieved through this post-processing strategy enhances the energy transfer from excitons to doped ions, providing guidance for achieving efficient and stable doped perovskite NCs.