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Ion irradiation effects on Sb-rich GaSb films
摘要： Here we show the formation of amorphous, non-stoichiometric GaSb films by magnetron sputtering and the ion irradiation effects on the films. GaSb films in the 20–300 nm thickness range were deposited by magnetron sputtering on SiO2/Si substrates at room temperature and subsequently irradiated with 17 MeV Au+7 ions at different fluences. Structural, compositional, and morphological characterizations were performed by means of x-ray diffraction, Rutherford backscattering spectrometry, x-ray photoelectron spectroscopy, scanning electron microscopy and x-ray absorption fine structure analyses. We could verify that, throughout the above-mentioned thickness range, films were amorphous, with excess Sb to the ratio 1:2 (Ga:Sb). The initially compact films attained a foam-like structure after irradiation, with significant swelling that is dependent on the initial film thickness: the thicker the film, the more it swelled. The excess Sb attained different oxidation states depending on film thickness and this influenced the final density of the films, thus influencing the swelling. The local atomic structure around Ga atoms was also investigated, revealing a decrease in Ga–Sb scattering contribution with increasing irradiation fluence, at the same time as the increase in Ga–O scattering for irradiation fluence above 1×1014 at/cm2 (inclusive).
关键词： XPS,XAFS,RBS,GaSb films,ion irradiation,XRD,magnetron sputtering
更新于2025-09-09 09:28:46
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Catechol oxidase mimetic activity of cadmium sulfide nanoparticles for the oxidation of L- 3,4 -dihydroxyphenylalanine
摘要： In the present work we have investigated the oxidation of L-3,4 -dihydroxyphenylalanine (L-Dopa) using colloidal cadmium sulfide nanoparticles (CdS NPs) as a photocatalyst. The CdS NPs were synthesized and characterized using UV-visible absorption spectroscopy, transmission electron microscopy (TEM) and powder X-ray diffraction (XRD). It was demonstrated that the as-prepared CdS NPs mimiced the activity of the catechol oxidase enzyme. To the best of our knowledge, this is the first report on the oxidation of L-Dopa using semiconductor NPs. The kinetic analysis was carried out using the Michaelis-Menten equation. The results observed that the CdS NPs oxidized L-Dopa within 30 min of irradiation using a 200 W Hg(Xe) arc lamp. The oxidation product was identified using high performance liquid chromatography (HPLC). The HPLC analyses were carried out on a reverse-phase C18 column under isocratic conditions using methanol/water (10/90) as the mobile phase. The retention time of the product matched with that of dopachrome. The mechanistic studies indicated the participation of hydroxyl radicals (?OH) in the photocatalytic oxidation of L-Dopa.
关键词： CdS NPs,semiconductor,irradiation,photocatalytic,catechol oxidase
更新于2025-09-09 09:28:46
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Fast electron transfer and enhanced visible light photocatalytic activity by using poly-o-phenylenediamine modified AgCl/g-C3N4 nanosheets
摘要： Exfoliation of bulk graphitic carbon nitride (g-C3N4) into two-dimensional (2D) nanosheets is one of the effective strategies to improve its photocatalytic properties so that the 2D g-C3N4 nanosheets (CN) have larger specific surface areas and more reaction sites. In addition, poly-o-phenylenediamine (PoPD) can improve the electrical conductivity and photocatalytic activity of semiconductor materials. Here, the novel efficient composite PoPD/AgCl/g-C3N4 nanosheets was first synthesized by a precipitation reaction and the photoinitiated polymerization approach. The obtained photocatalysts have larger specific surface areas and could achieve better visible-light response. However, silver chloride (AgCl) is susceptible to agglomeration and photocorrosion. The PoPD/AgCl/CN composite exhibits an extremely high photocurrent density, which is three times that of CN. Obviously enhanced photocatalytic activities of PoPD/AgCl/g-C3N4 are revealed through the photodegradation of tetracycline. The stability of PoPD/AgCl/CN is demonstrated based on four cycles of experiments that reveal that the degradation rate only decreases slightly. Furthermore, ?O2? and h+ are the main active species, which are confirmed through a trapping experiment and ESR spin-trap technique. Therefore, the prepared PoPD/AgCl/CN can be considered as a stable photocatalyst, in which PoPD is added as a charge carrier and acts a photosensitive protective layer on the surface of the AgCl particles. This provides a new technology for preparing highly stable composite photocatalysts that can effectively deal with environmental issues.
关键词： AgCl,Visible light irradiation,Poly-o-phenylenediamine,g-C3N4 nanosheets,Photocatalytic
更新于2025-09-09 09:28:46
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Enhanced photocatalytic performance of sphere-like AgCl/ rGO catalysts under simulated and natural sunlight irradiation
摘要： Here we prepared sphere-like AgCl by stirring in the presence of sodium oleate, and loaded it on the surface of reduced graphene oxide (rGO) to form sphere-like AgCl/ rGO composite. Sphere-like AgCl exhibited enhanced degradation e?ciency after the inserting of rGO with degrading 80.6% of tetracycline (TC) within 90 min, which was about 15.4% higher than pristine spherical AgCl (65.2%) under simulated sunlight irradiation. Moreover, ?ve times cycling test of the obtained samples had revealed the improved stability of AgCl/ rGO. The remarkable photocatalytic activity was mainly due to the better interaction between AgCl and rGO, where charge separation and transfer as well as the utilization of sunlight were boosted. Improved photocatalytic stability was majorly ascribed to the fast electrons transfer from AgCl to rGO before the reduction of Ag+ to Ag. Besides, a possible photocatalytic reaction mechanism under simulated sunlight was proposed. Meanwhile, AgCl/ rGO also exhibited better photocatalytic e?ciency for the degradation of TC under natural sunlight irradiation (73.2%), which is hopeful for practical application of photocatalysts.
关键词： Natural sunlight irradiation,Sphere-like AgCl/ rGO,Tetracycline,Photocatalyst
更新于2025-09-09 09:28:46
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Photoelectrocatalytic Reduction of Carbon Dioxide to Methanol using CuFe2O4 Modified with Graphene Oxide under Visible Light Irradiation
摘要： Photoelectrocatalytic reduction of CO2 into valuable products can provide energy in a sustainable way with levelling off the concentration of CO2 in our environment. In this study, graphene oxide (GO) incorporated with copper ferrite (CuFe2O4) has been employed to enhance photoelectrocatalytic CO2 reduction under visible light. The TEM and XPS characterization indicated a strong interaction between the CuFe2O4 and GO in the hybrid catalyst. The GO incorporation reduced the e-/h+ recombination in the hybrid catalyst by trapping the photoexcited electrons from CuFe2O4 leading to high methanol yield of 28.8 μmole/Lcm-2 at 20.5% quantum efficiency. The incident photon current efficiency (IPCE) and Faradaic efficiency for methanol formation were observed 8.02% and 87% respectively. The results showed that the photoelectrocatalytic activity for CO2 reduction can be improved by incorporating GO with CuFe2O4 and it provides a universal platform to fabricate GO-CuFe2O4 based hybrid photocatalyst with promising applications in CO2 reduction.
关键词： Visible light irradiation,CuFe2O4,CO2,Graphene oxide,Photoelectrocatalytic reduction,Methanol
更新于2025-09-09 09:28:46
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Dynamical processes of low-energy carbon ion collision with the graphene supported by diamond
摘要： The dynamical processes of a low-energy carbon ion collision with the graphene sheet supported by diamond at three impact positions are studied by using empirical potential molecular dynamics simulations. The energy transformation and the structural evolution have been studied. Five types of processes are observed: adsorption, hybridization, defects formation in diamond, atom emission and transmission. We find that the irradiation damage is closely related to the incident energy and impact position. In our simulations, as the projectile collides at a graphene atom, it transfers most of its energy to the primary knock-on atom, and defects are created in graphene. When the projectile moves perpendicular towards the center of a C-C bond in the graphene sheet, the energy transferred from the projectile to the atoms associated with the bond increases firstly and then decreases with the increasing incident energy, and the graphene sheet remains two-dimensional crystal structure after collision when the incident energy is larger than 360 eV. While the impact location is the center of a hexagonal ring on the graphene sheet, the energy transferred from the projectile to the atoms of the target ring is very small regardless of how large is the incident energy, and the graphene sheet is able to keep perfect crystal structure when the incident energy is larger than 34 eV.
关键词： diamond,carbon ion collision,graphene,irradiation damage,molecular dynamics simulations
更新于2025-09-09 09:28:46
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X-Ray Thermoluminescence Dosimetry Characterization of Commercially Available CVD Diamond
摘要： High quality commercially available CVD diamonds are being tested in novel clinical high energy photons, hadron therapy, and high energy physics applications. In the present work, the authors report on the thermoluminescence (TL) and dosimetry properties of commercial synthetic CVD diamond sample from Element6, exposed to X-ray irradiation at dose rates of 3.9–120 Gy min?1 from 0.13 to 90 Gy. The TL glow curves are composed of four peaks with maxima at about 104, 150, 210, and 280 °C and activation energies of 0.78, 0.79, 0.81, and 1.0 eV, respectively. The dose response of the area under TL glow curves is linear at doses lower than 0.6 Gy, supralinear between 0.6 and 6 Gy and sublinear at higher doses. The samples exhibited a strong TL fading of the low temperature 104 °C peaks that fades away around 120 min after irradiation, which is accompanied by increasing of the 210 and 280 °C peaks. The measured TL cycle reproducibility was very good, in spite of the fading exhibited by the lower temperature peak, with values of 0.1–3.0% at different dose rates and doses. It is concluded that CVD commercially single crystal electronic grade diamond may be securely used in clinical radiotherapy.
关键词： dosimetry,fading,thermoluminescence,diamond CVD crystal,X-ray irradiation
更新于2025-09-09 09:28:46
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UV?C irradiation as an alternative treatment technique: Study of its effect on microbial inactivation, cytotoxicity, and sensory properties in cranberry-flavored water
摘要： The impact of UV-C irradiation at 254 nm on microbial inactivation, cytotoxicity, and sensory properties of cranberry-flavored water (CFW) was studied using a continuous flow-through system. Two different bacterial outbreak strains Escherichia coli ATCC 700728 and Salmonella enterica serovar Muenchen ATCC BAA 1764 were inactivated by more than 5 log10 at an UV-C fluence of 12 mJ?cm-2 and 16 mJ?cm-2 from an initial concentration of approximately 8 log CFU?mL-1 with D values of 2.11 and 3.14 mJ?cm-2, respectively. Cytotoxicity evaluation of CFW in human endothelial cells (EA.hy926) demonstrated no toxic effects up to a maximum delivered UV-C fluence of 120 mJ?cm-2. Quantitative Descriptive Analysis (QDA) was performed to evaluate the sensory attributes of UV-C irradiated CFW at two (30 and 120 mJ?cm-2) UV-C fluence levels. Our results suggested that UV-C irradiated CFW had no significant difference (p > 0.05) in sensory attributes up to a fluence of 30 mJ?cm-2 which is below the FDA-recommended UV-C fluence (40 mJ?cm-2) for the inactivation of E. coli and Salmonella. Overall, this research suggests that UV-C treatment of CFW can achieve effective microbial inactivation, without the generation of cytotoxic effects, and also can retain its sensory attributes. These results demonstrated that UV-C irradiation can be an alternative treatment technique in processing of beverages while maintaining food safety and quality.
关键词： Microbial inactivation,Cytotoxicity,UV-C irradiation,Cranberry-flavored water,Continuous flow-through system,Fluence,Sensory evaluation
更新于2025-09-09 09:28:46
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Ag modified ZnS for photocatalytic water pollutants degradation: influence of metal loading and preparation method
摘要： In this paper, the photocatalytic degradation of organic pollutants was investigated using Ag/ZnS nanoparticles at different noble metal loadings. The photocatalysts were prepared at room temperature by two different methods: photodeposition and chemical reduction. The obtained samples were characterized by Specific surface area measurement, X-ray photoelectron spectroscopy, X-ray Powder diffraction, ultraviolet-visible diffuse reflectance and Raman spectroscopy. The X-ray photoelectron spectroscopy spectra showed that Ag is present on ZnS surface as intermediate state between nanostructured Ag0 and Ag2O. Moreover, the addition of silver caused a significant change of the absorption spectrum of bare ZnS, resulting in higher absorbance in the visible region, due to the Ag surface plasmon band. Methylene blue (MB) was used to evaluate the photocatalytic activity of the prepared samples. The best photocatalytic activity was observed using the sample at 0.1 wt% Ag loading prepared by chemical reduction method. In particular, the almost complete MB degradation was achieved using UV-LEDs as light sources and 6 g L-1 of catalyst dosage. Finally, the optimized photocatalyst was also effective in the degradation of phenol in aqueous solution under UV irradiation.
关键词： Ag/ZnS,methylene blue,silver loading,UV irradiation,phenol
更新于2025-09-09 09:28:46
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Effect of 200?MeV Ag15+ ion beam irradiation at different fluences on WO3 thin films
摘要： The physical properties of thin films can be modified by swift heavy ion (SHI) beam irradiation of the target material. Spray-deposited tungsten trioxide (WO3) thin films of thickness 89 nm were irradiated with 200 MeV Ag15+ ion beam at various fluences of 5 × 1011, 1 × 1012, 5 × 1012 and 1 × 1013 ions/cm2. The X-ray diffraction pattern of the pristine film was orthorhombic, while the irradiated film became amorphous at different fluences except for 5 × 1012 ions/cm2; this may be due to the re-crystallization effect induced by irradiation. The observed Raman modes for the pristine film were in good agreement with those reported for the irradiated WO3 films. The intensity of Raman peaks decreased upto 5 × 1012 ions/cm2 and vanished completely at further higher fluences. The optical transparency of the pristine film was much higher than that of irradiated ones. Both the direct and indirect band gaps showed a red shift. AFM data revealed significant surface modifications after irradiation. Transport properties were also studied for both the pristine and irradiated films by the Hall effect. A decrease in resistivity was observed with the increase in fluence. These results are discussed in this paper.
关键词： WO3,Hall effect,Raman spectra,Indirect band gap,Irradiation
更新于2025-09-09 09:28:46