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Graphene Heterostructure Integrated Optical Fiber Bragg Grating for Light Motion Tracking and Ultrabroadband Photodetection from 400 nm to 10.768 μm
摘要： Integrated photonics and optoelectronics devices based on graphene and related 2D materials are at the core of the future industrial revolution, facilitating compact and flexible nanophotonic devices. Tracking and detecting the motion of broadband light in millimeter to nanometer scale is an unfold science which has not been fully explored. In this work, tracking and detecting the motion of light (millimeter precision) is first demonstrated by integrating graphene with an optical fiber Bragg grating device (graphene-FBG). When the incident light moves toward and away from the graphene-FBG device, the Bragg wavelength red-shifts and blue-shifts, indicating its light motion tracking ability. Such light tracking capability can be further extended to an ultrabroad wavelength range as all-optical photodetectors show the robust response from 400 nm to 10.768 μm with a linear optical response. Interestingly, it is found that graphene-Bi2Te3 heterostructure on FBG shows 87% higher photoresponse than graphene-FBG at both visible and telecom wavelengths, due to stronger phonon-electron coupling and photo-thermal conversion in the heterostructure. The device also shows superior stability even after 100 d. This work may open up amazing integrated nanophotonics applications such as astrophysics, optical communication, optical computing, optical logic gating, spectroscopy, and laser biology.
关键词： 2D materials,graphene,ultrabroadband photodetection,heterostructures,optical fiber Bragg grating,light motion tracking
更新于2025-11-28 14:24:03
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Enhanced Charge Separation in g-C3N4 – BiOI Heterostructures for Visible Light Driven Photoelectrochemical Water Splitting
摘要： Heterojunctions of the low bandgap semiconductor bismuth oxyiodide (BiOI) with bulk multilayered graphitic carbon nitride (g-C3N4) and few layered graphitic carbon nitride sheets (g-C3N4-S) are synthesized and investigated as an active photoanode material for sunlight driven water splitting. HR-TEM and elemental mapping reveals formation of a unique heterostructure between BiOI platelets and the carbon nitride (g-C3N4 and g-C3N4-S) network that consisted of dendritic BiOI nanoplates surrounded by g-C3N4 sheets. The presence of BiOI in g-C3N4-S/BiOI and g-C3N4-S/BiOI nanocomposites extends the visible light absorption profile from 500 nm up to 650 nm. Due to excellent charge separation in g-C3N4/BiOI and g-C3N4-S/BiOI, evident from quenching of the carbon nitride photoluminescence (PL) and a decrease in the PL lifetime, a significant increase in photoelectrochemical performance is observed for both types of g-C3N4-BiOI heterojunctions. In comparison to heterojunctions of bulk g-C3N4 with BiOI, the nancomposite consisting of few layered sheets of g-C3N4 and BiOI exhibits higher photocurrent density due to lower recombination in few layered sheets. A synergistic trap passivation and charge separation is found to occur in the g-C3N4-S/BiOI nanocomposite heterostructure which results in a higher photocurrent and a lower charge transfer resistance.
关键词： visible light driven photocatalysis,earth abundant semiconductor heterostructures,Graphenic semiconductors,photoelectrochemistry
更新于2025-11-21 11:01:37
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Tuning the wettability and photocatalytic efficiency of heterostructure ZnO-SnO2 composite films with annealing temperature
摘要： ZnO-SnO2 composite films were spin-coated and annealed at different temperatures. The characteristics of the films were studied by using XRD, FESEM, AFM, FT-IR and UV–Vis spectroscopy. The wetting nature of the films was assessed by observing the water contact angle by sessile drop method. It was seen that the annealing temperature had a significant role in increasing the surface roughness. This leads to a change in water contact angles which are consistent with the Wenzel state of wetting. Photodegradation of model pollutants in liquid phase (cationic methylene blue, anionic methyl orange) and solid phase (octadecanoic acid) was performed to measure the photocatalytic efficiency of the films. The enhanced photocatalytic efficiency of films annealed at higher temperatures is due to better crystallinity and formation of heterostructure that inhibits the re-combination of charge entities (electron-hole).
关键词： Roughness,Contact angles,Heterostructures,Photocatalysis
更新于2025-11-19 16:56:35
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Composition-gradient ZnO/Zn(S,O) heterostructure nanorod arrays and their cathodoluminescence
摘要： Well-aligned ZnO/Zn(S,O) heterostructure nanorods have been synthesized through a well-designed chemical vapor deposition synthesis process. The as-synthesized ZnO/Zn(S,O) heterostructures exhibit a single crystal characteristic and a transitive interface with obvious composition gradient. X-ray Energy dispersive spectrometer (EDS) analysis demonstrates that ZnS-phase is rich in the nanorod bottom during the initial nucleation process and the S element content has a drastic decrease along the heterostructure nanorod from the bottom to the top, while O element is spatially detected in the whole rod. Room-temperature cathodoluminescence measurements verify two UV emissions at 330 nm and 385 nm for respective Zn(S,O) and ZnO phases with a strong defect-related emission band in visible range. Finally, the growth mechanism and optical emissions of ZnO/Zn(S,O) heterostructure nanorods are discussed.
关键词： ZnS,Heterostructures,ZnO,Synthesis,Cathodoluminescence
更新于2025-11-14 17:15:25
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Surface decoration of BiOCl with BiVO<sub>4</sub> particles towards enhanced visible-light-driven photocatalytic performance
摘要： BiVO4/BiOCl p-n junctioned photocatalysts were synthesized by surface replacement of pre-synthesized BiOCl with BiVO4 via a hydrothermal route. BiVO4 particles were decorated on the surface of BiOCl, the structures of which were favored of maximizing absorption of visible light. The photocatalytic activity of the heterojunctioned composites were evaluated by degradation of Rhodamine B (RhB) dye under visible light illumination. The results indicated that the composites exhibited superior efficiencies for RhB photodegradation in comparison with pure BiOCl, BiVO4 and BiOCl/BiVO4 with similar compositions. The 30% BiVO4/BiOCl exhibited an optimal photocatalytic activity due to the combinative effects of large visible-light absorbance and carrier separation. Experiments on scavenging active intermediates demonstrated that the enhanced photoactivity was primarily attributed to the formation of p-n junction. An effective built-in electric field was formed by the interface between p-type BiOCl and n-type BiVO4, which promoted the efficient separation of photoinduced electron-hole pairs.
关键词： visible light absorption,BiVO4 decorated BiOCl,surface replacement,heterostructures,charge carrier separation
更新于2025-11-14 17:04:02
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Ligand Engineering for Improved All‐Inorganic Perovskite Quantum Dot‐MoS <sub/>2</sub> Monolayer Mixed Dimensional van der Waals Phototransistor
摘要： Combining intriguing physical properties of 2D crystals and intrinsically remarkable optical properties of halide perovskite quantum dots (QDs), the 0D–2D perovskite QD–based mixed dimensional van der Waals heterostructure (MvdWH) is considered as promising for optoelectronic applications. Even though the interfacial electronic structure of MvdWHs is sufficiently engineered to manipulate the charge carrier behavior, the issue of interfacial charge transfer efficiency originating from the residue ligands that are inevitably introduced by the QDs is still prominently remained. From this perspective, for the first time, a solution-processed surface ligand density control strategy is demonstrated to balance the QD surface passivation and the interfacial charge carrier extraction and injection efficiency in the 0D–2D MvdWH system. The accurate adjustment of ligand density outside QDs enables the subsequent modulation on interfacial charge carrier transfer efficiency from the aspect of electronic and optoelectronic properties. Furthermore, such kind of ligand engineering toward MvdWH interface is substantially demonstrated in a photogating mechanism–based phototransistor with an improved photoresponsivity as high as 1.13 × 105 A W?1. These results may push forward the evolution of 0D–2D mixed dimensional van der Waals optoelectronics.
关键词： mixed-dimensional van der Waals heterostructures,perovskite quantum dots,phototransistors,MoS2,ligand engineering
更新于2025-11-14 17:04:02
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In-Situ Synthesis of Nb2O5/g-C3N4 Heterostructures as Highly Efficient Photocatalysts for Molecular H2 Evolution under Solar Illumination
摘要： This work focuses on the synthesis of heterostructures with compatible band positions and a favourable surface area for the efficient photocatalytic production of molecular hydrogen (H2). In particular, 3‐dimensional Nb2O5/g‐C3N4 heterostructures with suitable band positions and high surface area have been synthesized employing a hydrothermal method. The combination of a Nb2O5 with a low charge carrier recombination rate and a g‐C3N4 exhibiting high visible light absorption resulted in remarkable photocatalytic activity under simulated solar irradiation in the presence of various hole scavengers (triethanolamine (TEOA) and methanol). The following aspects of the novel material have been studied systematically: the influence of different molar ratios of Nb2O5 to g‐C3N4 on the heterostructure properties, the role of the employed hole scavengers, and the impact of the co‐catalyst and the charge carrier densities affecting the band alignment. The separation/transfer efficiency of the photogenerated electron‐hole pairs is found to increase significantly as compared to that of pure Nb2O5 and g‐C3N4, respectively, with the highest molecular H2 production of 110 mmol/g·h being obtained for 10 wt % of g‐C3N4 over Nb2O5 as compared with that of g‐C3N4 (33.46 mmol/g·h) and Nb2O5 (41.20 mmol/g·h). This enhanced photocatalytic activity is attributed to a sufficient interfacial interaction thus favouring the fast photogeneration of electron‐hole pairs at the Nb2O5/g‐C3N4 interface through a direct Z‐scheme.
关键词： Z‐Scheme,H2 evolution,hydrothermal synthesis,graphitic carbon nitride,photocatalysis,heterostructures,Niobium(V) oxide
更新于2025-11-14 17:03:37
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Visible-light-driven g-C3N4/Cu2O heterostructures with efficient photocatalytic activities for tetracycline degradation and microbial inactivation
摘要： g-C3N4/Cu2O composites were successfully synthesized by a facile chemical precipitation method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM) and UV diffuse reflectance spectroscopy (UV-DRS) techniques were employed to characterize the as-synthesized photocatalysts. The photocatalytic experiments indicated that the g-C3N4/Cu2O composites displayed higher photodegradation activity of tetracycline (TC) and inactivation efficiencies of Escherichia coli (E. coli) as well as Fusarium graminearum (F. graminearum) in comparsion with bare g-C3N4 and Cu2O under visible light irradiation. Photoluminescence (PL) spectra implied that the heterojunction between g-C3N4 and Cu2O could efficiently promote the separation efficiency of photo-induced charge carriers. Active species trapping experiment and electron spin resonance (ESR) analysis revealed that ?O2-, ?OH and h+ played important roles in the photocatalytic process. This study could provide new insights into the design of multifunctional g-C3N4-based photocatalysts for environmental purification.
关键词： inactivation mechanism,tetracycline,heterostructures,photocatalysis,g-C3N4/Cu2O
更新于2025-11-14 15:29:11
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Single process CVD growth of hBN/Graphene heterostructures on copper thin films
摘要： In this study, we have successfully grown hBN/graphene heterostructures on copper thin films using chemical vapor deposition in a single process. The first and most surprising result is that graphene grows underneath hBN and adjacent to the Cu film even though it is deposited second. This was determined from cross-sectional TEM analysis and XPS depth profiling, which chemically identified the relative positions of hBN and graphene. The effect of various growth conditions on graphene/hBN heterostructures was also studied. It was found that a pressure of 200 torr and a hydrogen flow rate of 200 sccm (;1 H2/N2) yielded the highest quality of graphene, with full surface coverage occurring after a growth time of 120 min. The resulting graphene films were found to be approximately 6–8 layers thick. The grain size of the nanocrystalline graphene was found to be 15–50 nm varying based on growth conditions.
关键词： XPS depth profiling,copper thin films,TEM analysis,hBN/graphene heterostructures,chemical vapor deposition
更新于2025-11-14 14:32:36
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Resonance Tunneling Phenomena in Two-Dimensional Multilayer van der Waals Crystalline Systems
摘要： Works, mostly experimental, concerning the most interesting features of application of the resonant tunneling spectroscopy to a new type of heterosystems, van der Waals heterostructures, have been briefly reviewed. These heterostructures appeared after the recent discovery of two-dimensional crystals, which are a new class of materials beginning with graphene. The role of the angular matching of crystal lattices of conducting graphene electrodes of van der Waals systems in carrier tunneling between them has been analyzed together with the closely related problems of satisfaction of conservation laws in tunneling transitions. Manifestations of multiparticle correlation interactions between carriers in van der Waals systems such as Wigner crystallization of electrons in a two-dimensional electron gas in a magnetic field and Bose condensation of excitons in parallel two-dimensional electron gases have been briefly discussed.
关键词： angular matching,momentum conservation,resonant tunneling spectroscopy,graphene,two-dimensional crystals,Wigner crystallization,van der Waals heterostructures,Bose condensation
更新于2025-09-23 15:23:52