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At least 667 records · Page 37

Attention-based 3D – convolutional neural network model for mechanical property predictions using visible light images in metal additive manufacturing

Additive manufacturing (AM), while commonly used for rapid prototyping and creating components with complex geometries, has not been widely adopted for critical applications across the aerospace, automotive, defense, energy, and medical industries. This is, in part, due to the challenges of controlling flaws and uncertainty in the mechanical behavior of additively manufactured components. In recent years, there has been an increase in research aimed at predicting the final mechanical properties of additively manufactured components during the printing process. To address these issues, a 3D-CNN model was trained using low-cost in situ visible-light camera data, anomaly classifications, and the chosen process parameters to predict the ultimate tensile strength (UTS), yield strength (YS), total elongation (TE), and uniform elongation (UE). The 3D-CNN layers of the model employed attention mechanisms to prioritize features in the data, thereby improving prediction accuracy. Furthermore, the effect of each process parameter and anomaly class is investigated using attention-based dynamic sigmoid weighted gates to interpret the influence each class has on the final prediction. Different combinations of the in situ data were fed into the 3D-CNN, with varying amounts of image layers, to determine the ideal combination for predicting mechanical properties in situ. Here, the 3D-CNN model achieved mean absolute percentage errors (MAPE) below 5% for both UTS and YS while using only a single camera input and under half of the available image layers.

36 MATERIALS SCIENCE↗

Quantum size effects and tunable visible photoluminescence in a-Si:H/nc-Si:H superlattices

Quantum size effects are commonly observed in semiconductor nanocrystals and quantum dots. Here, we demonstrate unexpected quantum size effects in an unusual bulk system with multiple interfaces, consisting of alternating layers of nanocrystalline silicon (nc-Si:H) and amorphous silicon (a-Si:H) material thin films. The nc-Si:H layers consist of silicon nanocrystals embedded in an amorphous matrix, with an amorphous-crystalline interface separating the two structures. Plasma-enhanced chemical vapor deposition was utilized to grow nanocrystalline-amorphous silicon superlattices with a varying thickness of the nanocrystalline layer. Strong visible photoluminescence at room temperature was deconvoluted into individual peaks. As the nanocrystalline silicon layer thickness was increased from 5 to 20 nm, the photoluminescence spectra red-shifted with the emission wavelength varying as d 2 (d is the size of the nanocrystallites), the characteristic signature underlying quantum size effects. The size d of the nanocrystals was estimated by the measured shift of the Raman peak, and could be tuned by varying the thickness of the nc-Si:H layers. High resolution transmission electron microscopy show nanocrystals with a narrow size distribution, in an amorphous matrix. We also observe long wavelength photoluminescence from interfacial states that leads to persistent photconductivity. In conclusion nanocrystalline-amorphous superlattices offer a unique pathway for synthesizing embedded nanocrystals with controlled sizes and photonic signatures.

36 MATERIALS SCIENCE↗

YBa{sub 2}Cu{sub 3}O{sub 7−x}/BaTiO{sub 3} 1D Superconducting Photonic Crystal with Tunable Broadband Response in the Visible Range

Based on the transfer matrix method, we studied theoretically the transmittance of a 1D photonic crystal (PC), consisting of alternating layers of a dielectric material (BaTiO{sub 3}) and a superconductor (YBa{sub 2}Cu{sub 3}O{sub 7−x}). The dielectric properties of this system are described by the two fluid model. We have investigated the transmittance intensity and its bandwidth dependence on the superconductor thickness, incident angle, and temperature in the PC. It was found that the electromagnetic wave propagation can be controlled to be forbidden or allowed in certain wavelengths in the visible and ultraviolet range, and the photonic band gap (PBG) width can also be tuned varying these parameters. We showed that by increasing the thickness of the superconductor layer it is possible to control the number of PBGs in the structure. Also, we found that the frequency ranges of PBGs are sensitive to the incident angle and the polarization of the electromagnetic waves; the bandwidth of PBGs can be notably enlarged by increasing the angle in the TE polarization, but narrowed in the TM one. Additionally, we found that transmission is not markedly affected by temperature variation, but small shifts in the PBGs are presented. We hope these results can be of technical use for developing potential applications in optoelectronic devices.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

The visible laser absorption property of chromium-doped polyvinyl alcohol films: synthesis, optical and dielectric properties

New films for visible laser filter were fabricated from poly(vinyl alcohol), PVA, and various levels of chrome(III) chloride, CrCl{sub 3}, by a known simple process named casting. The structure order degree, complex interaction, as well as optical filtering characteristic of the PVA + xCrCl{sub 3} (x = 0.037, 0.37, 3.7, 18.5 and 37 wt%) samples were investigated via the diffraction of the X-ray, Fourier transform infrared spectroscopy and UV/Vis/NIR spectrum, respectively, while the behavior of optical limiting was tested by set-up laser limiting measurement. The increment of Cr{sup 3+}-doping level in the PVA gives some results as, (I) a marked increase in the degree of random structure of the samples, and (II) two clearly absorption peaks are seen around 428 nm and 608 nm with a progressive increase in the intensity and a slight shift to a higher wavelength. (III) Three distinguished energy gaps were clearly observed, as well as, (IV) the dielectric spectroscopy of the samples was decreased with increasing the Cr{sup 3+}-doping, which contributes to the strong interaction among the mixtures. Furthermore, at concentrations above 0.37 wt% of Cr{sup 3+}-doping, a notable decrease in the output detected laser power was observed.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

CSK hopping pattern model for visible light communication networks

This paper proposes a new channel access method for visible light communications. The transmitter uses the CSK hopping pattern mode to load data to the R, G, and B light-emitting diodes of LEDs and establishes the network access point (AP) of the LEDs for the illumination coverage area. The coordinator controls the work of each AP to ensure that it simultaneously uses different color patterns to distinguish its respective networks. When the receiver (mobile terminal) detects a particular color pattern in the illumination coverage area, it establishes a communication access network process with the AP that is transmitting the particular color pattern. The advantage of this method is that interference between adjacent APs can be avoided. In addition, due to the simplification of the access network, the proposed CSK hopping model can shorten delays in the terminal’s access network. Through modeling and simulation, it is found that this method can effectively support network power and reduce network delay. Moreover, the fairness and stability of terminals that access the network are improved to a certain extent.

42 ENGINEERING↗

High performance graphene-like thinly layered graphite based visible light photodetector

In this work, the drop casting method is utilized to obtain a thin graphene-like graphite layer as a photodetection layer on a SiO{sub 2}/Si substrate, and its performance is characterized to determine its potential use in commercial applications. The thin layer is formed by first synthesizing graphite soot from a butane flame before being turned into a liquid solution and drop-casted onto the substrate to form a thin graphene-like graphite film. Field emission scanning electron microscope and Raman vibrational mode analyses indicate that the fabricated graphene-like graphite layer has characteristics similar to the graphene. The graphene-like graphite photodetector demonstrates a narrow photoresponse from 530 to 680 nm, covering visible sources from green to red. The responsivity and external quantum efficiency of the device under the illumination of red laser 660 nm is found to be around 148 mA W{sup −1} and 27.8% respectively and is faster than that reported for similar systems using graphene and reduced graphene oxide previously. A fast response time of 83.7 and 28 µs at a modulation frequency of 1.0 and 10000 Hz respectively from the graphene-like thinly layered graphite photodetector shows potential application for the development of low-cost carbon-based photodetectors in near future.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

A stable metal-covalent-supramolecular organic framework hybrid: enrichment of catalysts for visible light-induced hydrogen production

Cubic metal-covalent-supramolecular organic framework (MCSOF-1) hybrid has been created from the reaction of two molecular components and subsequent co-assembly with cucurbit[8]uril (CB[8]) in water. In the presence of CB[8], [Ru(bpy) 3 ] 2+ -based acylhydrazine 1·2Cl reacted with aldehyde 2·Cl to quantitatively yield six-armed precursor 3·8Cl through the generation of MCSOF-1. MCSOF-1 combines the structural features of metal-, covalent- and supramolecular organic frameworks. Its periodicity in water and in the solid state was confirmed by synchrotron X-ray scattering and diffraction experiments. Finally, MCSOF-1 could enrich discrete anionic polyoxometalates (POMs), maintain periodicity in acidic medium, and remarkably facilitate visible light-induced electron transfer from its [Ru(bpy) 3 ] 2+ units to enriched POMs, leading to enhanced catalysis of the POMs for the reduction of proton to H 2 in both aqueous (homogeneous) and organic (heterogeneous) media.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Solution synthesis of two-dimensional zinc oxide (ZnO)/molybdenum disulfide (MoS 2 ) heterostructure through reactive templating for enhanced visible-light degradation of rhodamine B

Numerous inorganic materials have been identified as potential candidates for high-performance photocatalysts. However, their solar-to-energy conversion efficiencies still fail to meet commercial requirements. Here, the main hurdle is the rapid recombination of photoexcited electrons and holes in single-phase materials. A viable predicted approach to suppress charge recombination is coupling two materials to form a two-dimensional (2D) heterostructure that physically separates photoinduced electrons and holes in different layers. In this work, the heterostructure-based paradigm was tested and a scalable solution synthesis of epitaxial ZnO-MoS 2 heterostructure was developed. A 2D ZnO-MoS 2 heterostructure was synthesized under hydrothermal conditions by stabilizing intermediate Zn-hydroxide states on a functionalized MoS 2 surface. Detailed characterization showed the formation of multilayer heterostructure with MoS 2 flakes intercalated between large size ZnO plates. The performance of this heterostructure was evaluated using photocatalytic degradation of rhodamine B. A degradation efficiency of 70% was measured within 90 minutes of visible-light irradiation, almost doubling the efficiency of the corresponding single-phase materials or their physical mixtures.

2D heterostructure↗

Enhanced visible light photocatalytic water reduction from a g-C 3 N 4 /SrTa 2 O 6 heterojunction

In this paper, a new g-C 3 N 4 /SrTa 2 O 6 heterojunction photocatalyst was designed and prepared by chimie douce (soft chemistry) method where carbon nitride (g-C 3 N 4 ) was deposited over the metastable perovskite phase of SrTa 2 O 6 . The morphological study of the heterojunction using SEM and STEM revealed that g-C 3 N 4 nanofibers are dispersed uniformly on the surface of SrTa 2 O 6 plates leading to the intimate contact between them. The heterojunction could achieve a high and stable visible light photocatalytic H 2 generation of 137 mmol/h/mole of g-C 3 N 4 , which is much larger than the amount of hydrogen generated by one mole of pristine g-C 3 N 4 . Finally, a plausible mechanism for the observed enhanced photocatalytic activity for the heterojunction is proposed on the basis of effective charge separation of photogenerated electron-hole pairs, supported by band position calculations and photo-physical properties of g-C 3 N 4 and SrTa 2 O 6 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Fe 2 O 3 –TiO 2 core–shell nanorod arrays for visible light photocatalytic applications

By using the glancing angle deposition technique and post-deposition annealing, Fe 2 O 3 –TiO 2 core-shell nanorod arrays with specific crystalline states can be designed and fabricated. The Fe 2 O 3 –TiO 2 core-shell samples annealed at temperatures greater than 450°C formed α-Fe 2 O 3 and anatase TiO 2 , and showed higher catalytic efficiency for the degradation of methylene blue (MB) under visible light illumination when compared with pure anatase TiO 2 or α-Fe 2 O 3 nanorod arrays. Solar conversion of carbon dioxide and water vapor in the presence of Fe 2 O 3 –TiO 2 core-shell nanorod arrays was also investigated. Carbon monoxide, hydrogen, methane, and methanol along with other hydrocarbons were produced after only several hours’ exposure under ambient sunlight. It was determined that the core-shell structure showed greater efficiency for solar CO 2 conversion than the pure TiO 2 nanorod arrays.

Glancing angle deposition↗

Detailed assessment of diesel spray atomization models using visible and X-ray extinction measurements

The physical mechanisms characterizing the breakup of a diesel spray into droplets are still unknown. This gap in knowledge has largely been due to the challenges of directly imaging this process or quantitatively measuring the outcomes of spray breakup, such as droplet size. Recent x-ray measurements by Argonne National Laboratory, utilized in this work, provide needed information about the spatial evolution of droplet sizes in selected regions of the spray under a range of injection pressures (50–150 MPa) and ambient densities (7.6–22.8 kg/m3) relevant for diesel operating conditions. Ultra-small angle x-ray scattering (USAXS) measurements performed at the Advanced Photon Source are presented, which quantify Sauter mean diameters (SMD) within optically thick regions of the spray that are inaccessible by conventional droplet sizing measurement techniques, namely in the near-nozzle region, along the spray centerline, and within the core of the spray. To quantify droplet sizes along the periphery of the spray, a complementary technique is proposed and introduced, which leverages the ratio of path-integrated x-ray and visible laser extinction (SAMR) measurements to quantify SMD. The SAMR and USAXS measurements are then utilized to evaluate current spray models used for engine computational fluid dynamic (CFD) simulations. We explore the ability of a carefully calibrated spray model, premised on aerodynamic wave growth theory, to capture the experimentally observed trends of SMD throughout the spray. The spray structure is best predicted with an aerodynamic primary and secondary breakup process that is represented with a slower time constant and larger formed droplet size than conventionally recommended for diesel spray models. Additionally, spray model predictions suggest that droplet collisions may not influence the resultant droplet size distribution along the spray centerline in downstream regions of the spray.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Enhanced photocatalytic activity of Te-doped Bi{sub 2}MoO{sub 6} under visible light irradiation: Effective separation of photogenerated carriers resulted from inhomogeneous lattice distortion and improved electron capturing ability

Te-doped Bi{sub 2}MoO{sub 6} photocatalyst was hydrothermally synthesized, and nonmetal atoms Te were homogeneously incorporated into Bi{sub 2}MoO{sub 6} lattice with the substitution of Te{sup 4+} to Mo{sup 6+}. With increasing Te-doping concentration in Bi{sub 2}MoO{sub 6}, no detectable band-gap narrowing but more and more severe inhomogeneous lattice distortions were determined. The activity of Bi{sub 2}MoO{sub 6} photocatalyst was evaluated through methylene blue degradation under visible light irradiation (λ>410 nm) and was greatly enhanced by Te-doping. When Te-doped Bi{sub 2}MoO{sub 6} was synthesized at Te/Mo molar ratio of 7.5%, a maximum first-order rate constant of methylene blue degradation was obtained. The inhomogeneous lattice distortion generated an internal dipole moment, and the holes generated with the substitution of Te{sup 4+} to Mo{sup 6+} acted as the capturing centers of photogenerated electrons, thus the effective separation of photogenerated carriers was facilitated to result in a relatively high concentration of holes on the surface of Te-doped Bi{sub 2}MoO{sub 6} to be favorable for the efficient methylene blue degradation. - Graphical abstract: With the substitution of Te{sup 4+} to Mo{sup 6+}, effective separation of photogenerated carriers resulted from inhomogeneous lattice distortion and improved electron capturing ability is achieved to be responsible for enhanced photocatalytic activity of Te-doped Bi{sub 2}MoO{sub 6}. - Highlights: • Nonmetal Te is incorporated into Bi{sub 2}MoO{sub 6} with the substitution of Te{sup 4+} to Mo{sup 6+}. • Revealing inhomogeneous lattice distortion and improved electron capturing ability. • Effective separation of photogenerated carriers in Te-doped Bi{sub 2}MoO{sub 6} is achieved. • The mechanism of methylene blue degradation over Te-doped Bi{sub 2}MoO{sub 6} is proposed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Facile preparation of sphere-like copper ferrite nanostructures and their enhanced visible-light-induced photocatalytic conversion of benzene

Graphical abstract: - Highlights: • Spinel CuFe{sub 2}O{sub 4} nanospheres were successfully synthesized via a facile method. • CuFe{sub 2}O{sub 4} nanospheres showed high photocatalytic activity toward benzene. • Ethyl acetate, carboxylic acid and aldehyde were the intermediate products. - Abstract: Spinel copper ferrite nanospheres with diameters of about 116 nm were synthesized in high yield via a facile solvothermal route. The prepared nanospheres had cubic spinel structure and exhibited good size uniformity and regularity. The band-gap energy of CuFe{sub 2}O{sub 4} nanospheres was calculated to be about 1.69 eV, indicating their potential visible-light-induced photocatalytic activity. The dramatically enhanced photocatalytic activity of the CuFe{sub 2}O{sub 4} nanospheres was evaluated via the photocatalytic conversion of benzene under Xe lamp irradiation. By using the in situ FTIR technique, ethyl acetate, carboxylic acid and aldehyde could be regarded as the intermediate products, and CO{sub 2} was produced as the final product during the reaction process. This study provided new insight into the design and preparation of functional nanomaterials with sphere structure in high yield, and the as-grown architectures demonstrated an excellent ability to remove organic pollutants in the atmosphere.

36 MATERIALS SCIENCE↗

Photocatalytic hydrogen production using visible-light-responsive Ta{sub 3}N{sub 5} photocatalyst supported on monodisperse spherical SiO{sub 2} particulates

Graphical abstract: A simple and effective sol–gel process followed by nitridation in an NH{sub 3} flow has been developed to deposit Ta{sub 3}N{sub 5} semiconductor photocatalyst layers onto monodisperse spherical SiO{sub 2} particles. The obtained Ta{sub 3}N{sub 5}/SiO{sub 2} particles maintain an original spherical morphology of SiO{sub 2} and a sub-micrometer size with a narrow size distribution and without aggregation. The presence of SiO{sub 2} support shows at least no detrimental effects on photocatalytic activity, but tunes the secondary particle size to control dispersibility of the photocatalyst in the solution. - Highlights: • Fine nanoparticles of Ta{sub 3}N{sub 5} were immobilized on the surfaces of SiO{sub 2} giving SiO{sub 2}@Ta{sub 3}N{sub 5} core–shell spheres successfully produced H{sub 2} from methanol solution under visible light. • The presence of support (SiO{sub 2}) ensures the dispersion of the particulate in solution maintaining high photocatalytic activity of Ta{sub 3}N{sub 5}. • The obtained supported photocatalyst gives uniform size distribution and control the degree of dispersibility in the solution, which may control nature of light absorption and reflection of the photoreactor. - Abstract: Fine nanoparticles of Ta{sub 3}N{sub 5} (10–20 nm) were synthesized on the surfaces of SiO{sub 2} spheres with a diameter of ∼550 nm. A sol–gel method was used to modify the surface of SiO{sub 2} with Ta{sub 2}O{sub 5} from TaCl{sub 5} dissolved in ethanol in the presence of citric acid and polyethylene glycol. The resulting oxide composites were treated in an NH{sub 3} flow at 1123 K to form core–shell structured Ta{sub 3}N{sub 5}/SiO{sub 2} sub-microspheres. The obtained samples were characterized using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectra (EDX), transmission electron microscopy (TEM), and photocatalytic activity measurements for H{sub 2} evolution from an aqueous methanol solution. The XRD results demonstrate the expected sequential formation of Ta{sub 2}O{sub 5} layers, followed by Ta{sub 3}N{sub 5} after nitridation on the Ta{sub 2}O{sub 5}/SiO{sub 2} composite. SEM and TEM observations indicate that the obtained Ta{sub 3}N{sub 5}/SiO{sub 2} sub-microspheres have a uniform size distribution with high crystallinity and an obvious core–shell structure. The presence of support maintained the intrinsic photocatalytic activity of Ta{sub 3}N{sub 5} nanoparticles, but it did drastically improve the dispersion of the photocatalysts in the solution. This study proposes the use of an inert support in photocatalytic reactors to improve ease of handling the powder photocatalyst for gas-phase photocatalysis and the suspension of the solution, controlling nature of light harvesting and degree of scattering of the photoreactor.

36 MATERIALS SCIENCE↗

Highly efficient visible-light-induced photocatalytic activity of Bi{sub 2}WO{sub 6}/BiVO{sub 4} heterojunction photocatalysts

Highlights: • Bi{sub 2}WO{sub 6}/BiVO{sub 4} heterojunction photocatalysts were obtained using hydrothermal method. • Physicochemical properties played a significant role on photocatalytic efficiency. • Bi{sub 2}WO{sub 6}/BiVO{sub 4} heterogeneous structures were greatly enhanced for degradation of MB. • A tentative mechanism of charge transfer process in MB degradation was proposed. - Abstract: The Bi{sub 2}WO{sub 6}/BiVO{sub 4} heterojunction photocatalysts were synthesized by hydrothermal method. Physical properties of the heterojunction photocatalyst samples were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The XRD results indicated that BiVO{sub 4} retain monoclinic and tetragonal structures, while Bi{sub 2}WO{sub 6} presented as orthorhombic structure. The Brunauer, Emmett and Teller (BET) adsorption–desorption of nitrogen gas for specific surface area determination at the temperature of liquid nitrogen was performed on all samples. UV–vis diffuse reflectance spectra (UV–vis DRS) were used to identify the absorption range and band gap energy of the heterojunction photocatalysts. The photocatalytic performance of Bi{sub 2}WO{sub 6}/BiVO{sub 4} heterojunction photocatalysts was studied via the photodegradation of methylene blue (MB) under visible light irradiation. The results indicated that the heterojunction photocatalyst at 0.5:0.5 mole ratio of Bi{sub 2}WO{sub 6}:BiVO{sub 4} shows the highest photocatalytic activity.

36 MATERIALS SCIENCE↗

Effects of thermal treatment on the Mg{sub x}Zn{sub 1−x}O films and fabrication of visible-blind and solar-blind ultraviolet photodetectors

Highlights: • Single-phase wurtzite/cubic Mg{sub x}Zn{sub 1−x}O films were grown by RF magnetron sputtering technique. • We focus on the red-shift caused by annealing the Mg{sub x}Zn{sub 1−x}O films. • MSM-structured visible-blind and solar-blind UV photodetectors were fabricated. - Abstract: A series of single-phase Mg{sub x}Zn{sub 1−x}O films with different Mg contents were prepared on quartz substrates by RF magnetron sputtering technique using different MgZnO targets, and annealed under the atmospheric environment. The absorption edges of Mg{sub x}Zn{sub 1−x}O films can cover the whole near ultraviolet and even the whole solar-blind spectra range, and the solar-blind wurtzite/cubic Mg{sub x}Zn{sub 1−x}O films have been realized successfully by the same method. In addition, the absorption edges of annealed films shift to a long wavelength, which is caused by the diffusion of Zn atoms gathering at the surface during the thermal treatment process. Finally, the truly solar-blind metal-semiconductor-metal structured photodetectors based on wurtzite Mg{sub 0.445}Zn{sub 0.555}O and cubic Mg{sub 0.728}Zn{sub 0.272}O films were fabricated. The corresponding peak responsivities are 17 mA/W at 275 nm and 0.53 mA/W at 250 nm under a 120 V bias, respectively.

36 MATERIALS SCIENCE↗

Synthesis and VOC degradation ability of a CeO{sub 2}/WO{sub 3} thin-layer visible-light photocatalyst

Highlights: • Plasma-synthesized γ/ε-WO{sub 3} showed improvement of acetaldehyde decomposition. • Ferroelectricity of ε-WO{sub 3} slowed hole-electron recombination. • Synergistic effect between WO{sub 3} and CeO{sub 2} further enhanced photocatalytic activity. - Abstract: The plasma synthesis, characterization, and photocatalytic activity of WO{sub 3}, which consisted of a mixture of gamma WO{sub 3} and epsilon WO{sub 3} (γ/ε-WO{sub 3}), and physically mixed WO{sub 3} and CeO{sub 2} (WO{sub 3}/CeO{sub 2}) were investigated. Synergistic effects were observed in acetaldehyde photocatalysis experiments using γ/ε-WO{sub 3} or WO{sub 3}/CeO{sub 2}. The synergistic effect in the γ/ε-WO{sub 3} photocatalyst system is proposed to be the concurrent reduction of oxygen at gamma WO{sub 3} and oxidation of acetaldehyde at epsilon WO{sub 3}. It is hypothesized that acetaldehyde preferentially interacts with epsilon WO{sub 3} over gamma WO{sub 3} because of dipole–dipole interactions between them. In the case of the WO{sub 3}/CeO{sub 2} photocatalyst, the electron scavenging property of CeO{sub 2} aided charge carrier separation. As a result, WO{sub 3}/CeO{sub 2} exhibited excellent photocatalytic activity in volatile organic compound decomposition under visible light at room temperature.

36 MATERIALS SCIENCE↗

One-step reduction synthesis of Ag/Ag3PO4/AgBr sub-micron composites for enhanced visible photocatalytic degradation of methyl orange

Highlights: • Ag/Ag{sub 3}PO{sub 4}/AgBr photocatalysts were synthesized by a one-step reduction method. • The conditions affecting performances of the photocatalysts were optimized. • The main radicals responsible for degrading MO were investigated. • The Ag/Ag{sub 3}PO{sub 4}/AgBr photocatalyst presented excellent stability and recyclability. - Abstract: An efficient semiconductor composite, silver/silver orthophosphate/silver bromide, was successfully synthesized by a facile one-step reduction and ion exchange process. Its crystal structure, morphology, optical property, surface element composition were characterized by X-ray diffraction, scanning electron microscopy, ultraviolet-visible diffuse reflectance spectrometer and X-ray photoelectron spectrometer. The effects of composite proportion and synthesis duration on performances of as-prepared photocatalysts were investigated, and the results showed that Br/P molar ratio of 3 and the synthesis duration of 4 h were the optimum conditions. The radical scavenging experiments indicated that the hole and superoxide radical were the main active species in this reaction system. The Ag/Ag{sub 3}PO{sub 4}/AgBr-3 presented excellent stability and recyclability, maintaining 92% of degradation efficiency after 5 cycles. The good photocatalysis performance could be attributed to the formation of the heterojunction between Ag and Ag{sub 3}PO{sub 4}/AgBr.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗