The replacing and surpassing of some functions of traditional metal-based photocatalysts by low-cost and high-efficiency non-metal semiconductor materials have become a research hotspot in functional ...materials. In this paper, the ultra-thin nanoporous g-C.sub.3N.sub.4 nanosheets were successfully embedded with highly dispersed S quantum dots (S QDs) by ultrasonic-assisted in-situ growth method, which originates from the disproportionation reaction of sodium thiosulfate. The formation of the composite was proved by XRD, XPS, AFM, TEM and HRTEM and proved that S QDs with a size of 1-3.5 nm were uniformly embedded in the surface of ultra-thin nanoporous g-C.sub.3N.sub.4, in which a tight and uniform 0D/2D heterojunction structure was designed and built. Meanwhile, the photocatalytic mechanism was investigated. It showed that the tight Z-Scheme heterojunction structure formed between S QDs and g-C.sub.3N.sub.4 improved the redox activity as well as the transfer ability of photogenerated electron holes. The system exhibited excellent photocatalytic efficiency that the complete degradation of RhB was achieved within 90 min under visible-light irradiation and revealed high stability. We believe that this research is important for the development of low-cost and efficient non-metal photocatalysts. Graphical abstract
Floating-gate transistor lies at the heart of many aspects of semiconductor applications such as neural networks, analog mixed-signal, neuromorphic computing, and especially in nonvolatile memories. ...The purpose of this paper was to design a high-performance nanocrystal floating-gate transistor in terms of a large memory window, low power, and extraordinary erasing speeds. Besides, the transistor achieves a thin thickness of the tunnel gate oxide layer. In order to obtain the high-performance design, this work proposed a set of structure parameters for the device such as the tunnel oxide layer thickness, Interpoly Dielectric (IPD), dot dimension, and dot spacing. Besides, this work was successful in the virtual fabrication process and methodology to fabricate and characterize the 65nm nanocrystal floating-gate transistor. Regarding the results, while the fabrication process solves the limitation of the tunnel oxide layer thickness with the small value of 6nm, the performance of the transistor has been significantly improved, such as 2.8V of the memory window with the supply voltage of ±6V at the control gate. In addition, the operation speeds are compatible, especially the rapid erasing speeds of 2.03μ s, 28.6ns, and 1.6ns when the low control gate voltages are ±9V, ±12V, and ±15V, respectively.
In recent years, two-dimensional (2D) layered transition metal dichalcogenides (TMDs) have received significant attention due to their exceptional electrical and optical properties. Among these 2D ...materials, ReSsub.2 distinguishes itself through its unique optical and conductance anisotropy. Despite concerted efforts to produce high-quality ReSsub.2, the unique interlayer decoupling properties pose substantial challenges in growing large-area ReSsub.2 thin films, with the preparation of single layers proving even more complex. In this work, large-scale continuous monolayer and bilayer ReSsub.2 films were successfully grown on mica substrates using low-pressure chemical vapor deposition (LPCVD). Photodetectors were fabricated using the prepared high-quality ReSsub.2 films, and the devices presented stable photoresponse and enhanced response sensitivity. The production of continuous ReSsub.2 atomic layers heralds promising prospects for large-scale integrated circuits and advances the practical application of optoelectronics based on 2D layered materials.
Flower-like TiOsub.2 nanostructures were obtained by chemical oxidation of Ti foil using Hsub.2Osub.2 combined with subsequent annealing. This paper offers an analysis of the phase transformation of ...3D flower-like titanium dioxide nanostructures. The role of the annealing atmosphere, sample thickness, grain shape, and nanoflower size are discussed. The nanostructures were examined using SEM, XRD, and Raman spectroscopy. Due to the nature of these two processes, the morphology of these nanomaterials is complex, and is obtained through a reaction involving Ti foil and Hsub.2Osub.2 at 80°C. A distinction is made between the layer composed of small grains at the substrate/oxide interface, elongated crystal-like structures, and outer spongle-like film. The annealing parameters, such as atmosphere (air or argon) and temperature (450 or 600 °C), affect phase composition. The photoelectrochemical performance of the anode based on flower-like TiOsub.2 has been shown. The thickness and phase composition of the anodes are factors that strongly affect the photocurrent. The multiphase heterojunctions proposed for 3D flower-like TiOsub.2 photoanodes in photoelectrochemical (PEC) cells suppose that the conduction band of anatase should be above rutile. The highest photoelectrochemical performance was obtained for a photoanode composed of 20-40% anatase and an associated thickness of 0.75-1.5 µm.
Film-like Ag.sub.2O coatings have been obtained using electrochemical method, and their photoelectrochemical and spectral properties have been studied. The photocatalytic behavior of these samples in ...the process of reduction of carbon dioxide with water vapor has been studied. The possibility of formation of a number of organic compounds (acetaldehyde, acetone, isopropyl and ethyl alcohols, methane) upon irradiation of the systems with visible light has been established.
Photocatalysis is an effective technology for NO removal even at low concentrations in the ambient atmosphere. However, the low efficiency of this advanced process and the tendency of producing toxic ...byproducts hinder the practical application of photocatalysis. To overcome these problems, the Bi@Basub.2TiOsub.4/BaBisub.4Tisub.4Osub.15 photocatalytic composites were successfully prepared by a one-step hydrothermal method. The as-synthesized photocatalysts exhibited an efficient photocatalytic performance and generated low amounts of toxic byproducts. X-ray diffraction studies show that Bisup.3+ is successfully reduced on the surface of Basub.2TiOsub.4/BaBisub.4Tisub.4Osub.15 (BT/BBT). After L-Ascorbic acid (AA) modification, the photocatalytic NO removal efficiency of Bi@Basub.2TiOsub.4/BaBisub.4Tisub.4Osub.15 is increased from 25.55% to 67.88%, while the production of the toxic byproduct NOsub.2 is reduced by 92.02%, where the initial concentration of NO is diluted to ca. 800 ppb by the gas stream and the flow rate is controlled at 301.98 mL·minsup.−1 in a 150 mL cylindrical reactor. Furthermore, ambient humidity has little effect on the photocatalytic performance of theBi@Basub.2TiOsub.4/BaBisub.4Tisub.4Osub.15, and the photocatalyst exhibits excellent reusability after repeated cleaning with deionized water. The improved photocatalytic effect is attributed to the addition of AA in BT/BBT being able to reduce Bisup.3+ ions to form Bi nanoparticles giving surface plasmon effect (SPR) and generate oxygen vacancies (OVs) at the same time, thereby improving the separation efficiency of photogenerated carriers, enhancing the light absorption, and increasing the specific surface areas. The present work could provide new insights into the design of high-performance photocatalysts and their potential applications in air purification, especially for NO removal.
Magnetic nanoparticles embedded into semiconductors have current perspectives for use in semiconducting spintronics. In this work, 40 keV Fesup.+ ions were implanted in high fluences of (0.5 ÷ 1.5) × ...10sup.17 ion/cmsup.2 into an oxide semiconductor and single-crystalline TiOsub.2 plates of rutile structure with (100) or (001) face orientations. Microstructure, elemental-phase composition, and magnetic properties of the Fe-ion-implanted TiOsub.2 were studied by scanning and transmission electron microscopies (SEM and TEM), X-ray photoelectron (XPS) and Rutherford backscattering (RBS) spectroscopies, as well as vibrating-sample magnetometry (VSM). The high-fluence ion implantation results in the formation of magnetic nanoparticles of metallic iron beneath the irradiated surface of rutile. The induced ferromagnetism and observed two- or four-fold magnetic anisotropy are associated with the endotaxial growth of Fe nanoparticles oriented along the crystallographic axes of TiOsub.2.
Ternary boron-carbon-nitride compounds are the hardest, chemically stable, and most applicable semiconductors in optoelectronic devices. We investigate the quasi-particle and excitonic properties of ...type II o-BCsub.2N using many-body perturbation theory (MBPT). The state-of-the-art GW and BSE methods were used to determine the accurate band gap and excited-state characteristics of this material. We simulate the convergence test and structural optimization in DFT, which is the starting point for the GW calculation. We also compute the convergence test of the parameters in GW and BSE. As a result, the bandgap of our system is found to be 2.31eV and 1.95eV using the GW approximation and DFT-PBE, respectively. Since the valence and conduction band edges are located at different Brillouin zones, we decide that o-BCsub.2N is an indirect bandgap semiconductor. In addition, by applying the scissor operator, we corrected the quasi-particle bandgap, which shows almost the same result as the GW approximation. Furthermore, using the BSE algorithm, we calculate the optical bandgap of type II o-BCsub.2N to be 4.0eV with the excitonic effect and 4.4eV without the excitonic effect. The highest peaks of the imaginary dielectric function with the excitonic effect shift to a lower energy level at 11eV than without the excitonic effect at 13.5eV. The electron charge distribution is computed by fixing the hole position. Finally, we suggest that type II o-BCsub.2N is promising for the application of optoelectronic semiconductors.
A practical method for organic–inorganic hybrid heterojunction photodetector by spin-coating the cobalt phthalocyanine (CoPc) solution onto the β-gallium oxide (β-Gasub.2Osub.3) film is available to ...realize the sensitive detection of ultraviolet light signals. We have carefully measured and calculated the optoelectronic performance of the prepared device. The device demonstrates excellent rectification characteristics under different light intensities, and the rectification ratio reaches 144.96 under 900 μW/cmsup.2 at ±5 V. Benefiting from the construction of CoPc/Gasub.2Osub.3 heterojunction, the device shows an extremely low dark current of 5.73 fA, a high detectivity of 1.92 × 10sup.17 Jones, a responsivity of 18.4 mA/W, and a high light-to-dark current ratio of 3.76 × 10sup.6. In addition, the intrinsic physical mechanism of the device is investigated through the energy band diagram under different conditions. The device is equipped with the possibility to work under self-powered mode and has good stability in the air environment.
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