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Crystallographically oriented porous ZnO nanostructures with visible-blind photoresponse: controlling the growth and optical properties
摘要： We have grown catalyst-free crystallographically oriented porous ZnO nanostructures by pulsed laser deposition (PLD) method. The deposition was performed in two stages for each sample. In the first stage, self-seeding of ZnO was performed on the quartz substrate, and the angle of deposition (seeding-angle) was varied. Thus, the growth of seeds is different here. In the second stage, the deposition was performed at a glancing angle (at 85?) for the fixed duration of time to grow the nanostructures. These PLD-grown nanostructures acquire highly oriented wurtzite structure. We find that the seeding-angle during the first stage is the determining deposition parameter which influences the growth and other properties of these nanostructures in a controllable manner. The variation in seeding-angle systematically tunes the crystallographic orientation and porosity, which in turn influences the visible-blindness and ultraviolet (UV) photoresponse of these nanonetworks. Here we report the growth of completely defect-free crystallographically oriented nanostructures with necessary porosity for application in visible-blind UV photodetection.
关键词： Crystalline ZnO,catalyst-free ZnO,glancing angle deposition (GLAD),seeding,pulsed laser deposition (PLD),nanostructures
更新于2025-11-21 11:03:13
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Ultra-fast and high flexibility near-infrared photodetectors based on Bi2Se3 nanobelts grown via catalyst-free van der Waals epitaxy
摘要： van der Waals epitaxy (vdWe) method has recently attracted considerable interest due to its extensive application in the growth of layered structure materials. However, the growth process of vdWe is not completely understood. Here, we report the controlled growth process of Bi2Se3 nanobelts and study their photoresponse behaviour. The average length of nanobelts increases from 7 mm to 17 mm by adjusting the temperature of Bi2Se3 powder from 520 (cid:1)C to 530 (cid:1)C, however the average length becomes saturated with further increasing the source material temperature over 530 (cid:1)C. Such a change can be attributed to the competition between the process of Bi2Se3 molecule diffusion and the process of crystal formation-related chemical reaction, leading to a symmetrically studying for the growth process of catalyst-free vdWe growth of Bi2Se3 nanobelts. The photodetectors based on these Bi2Se3 nanobelts show excellent device performance in the near-infrared light range, including an ultra-fast photoresponse (trsing z 37 ms, tdecay z 62 ms), a high responsivity of 10.1 mA/W and a high detectivity of 4.63 (cid:3) 108 Jones. This high device performance could be related to the excellent carrier transport properties as Bi2Se3 nanobelt photodetectors also demonstrate a great potential for fabricating ?exible and wearable electronics by still showing stable photoresponse after bending the device for 200 times.
关键词： 2D NIR photodetectors,Catalyst-free van der Waals epitaxy,Bi2Se3 nanobelts
更新于2025-09-12 10:27:22
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Catalyst‐Free Vapor–Solid Deposition Growth of β‐Ga <sub/>2</sub> O <sub/>3</sub> Nanowires for DUV Photodetector and Image Sensor Application
摘要： Photodetection in the solar-blind deep-ultraviolet (DUV) regime (200–280 nm) has received significant attention for its many critical applications in military and civil areas. In this study, a vapor–solid synthesis technique for catalyst-free growth of single-crystalline β-Ga2O3 nanowires is developed. A photodetector made of the nanowires is highly sensitive to 265 nm DUV illumination with excellent photoresponse performance. The performance parameters including Ilight/Idark ratio, responsivity, specific detectivity and response speed can attain ≈103, ≈233 A W?1, ≈8.16 × 1012 Jones, and 0.48/0.04 s, respectively. Additionally, the detector has an abrupt response cutoff wavelength at ≈290 nm with a reasonable DUV/visible (250–405 nm) rejection ratio exceeding 102. It is also found that the device can operate properly at a large applied bias of 200 V with the responsivity being enhanced to as high as ≈1680 A W?1. Moreover, such a nanowires-based photodetector can function as a DUV light image sensor with a reasonable spatial resolution. Holding the above advantages, the present DUV photodetector based on catalyst-free grown β-Ga2O3 nanowires possesses huge possibility for application in future DUV optoelectronics.
关键词： DUV photodetectors,catalyst-free growth,nanowires,image sensors,β-Ga2O3
更新于2025-09-11 14:15:04
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Catalyst-Free Selective Oxidation of Diverse Olefins to Carbonyls in High Yield Enabled by Light under Mild Conditions
摘要： The selective oxidation of ole?ns, in particular, aromatic ole?ns to carbonyls, is of signi?cance in organic synthesis. In general, stoichiometric toxic oxidants or a high-cost catalyst is required. Herein we report a novel and practical light-enabled protocol for the synthesis of carbonlys in high yield through a catalyst-free oxidation of ole?ns using H2O2 as a clean oxidant. A broad scope of carbonyls can be synthesized in high yield, and no catalyst or toxic oxidant is required.
关键词： light-enabled,ole?ns,carbonyls,selective oxidation,H2O2,catalyst-free
更新于2025-09-11 14:15:04
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Efficient ambient-air-stable HTM-free carbon-based perovskite solar cells with hybrid 2D–3D lead halide photoabsorbers
摘要： The title reaction has been established, which offers a useful method for the construction of dihydrocoumarin frameworks in generally good chemical yields (up to 99%) and high diastereoselectivities (up to >95 : 5 dr). This reaction represents a good example of [4 + 2] cyclizations of para-quinone methide derivatives with electron-rich reaction partners under catalyst-free conditions.
关键词： [4 + 2] cyclization,dihydrocoumarin frameworks,Catalyst-free,para-quinone methide derivatives,homophthalic anhydrides
更新于2025-09-11 14:15:04
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Catalyst-Free Growth of a Zn2GeO4 Nanowire Network for High-Performance Transfer-Free Solar-Blind Deep UV Detection
摘要： Solar-blind deep-ultraviolet (DUV) photodetectors have attracted wide attention because of their extensive military and civil applications. The ternary oxide Zn2GeO4 is an ideal material with a wide bandgap (Eg = 4.69 eV). In this work, DUV photodetectors based on a ternary Zn2GeO4 nanowire (NW) network were fabricated on SiO2/Si substrates. Reactive ion etching of the SiO2/Si wafer was used to grow the NW network to avoid contamination of the Au catalyst during synthesis of the Zn2GeO4 NW network via high-temperature chemical vapor deposition. Photodetectors based the Zn2GeO4 NW revealed fast response and recovery times, which is attributed to the unique cross-junction barrier-dominated conductance of the NW network. Results showed that the ternary oxide-based NW network is an ideal building block for nanoscale solar-blind photodetectors with superior performance.
关键词： Zn2GeO4 nanowire,ultraviolet photodetector,catalyst-free
更新于2025-09-10 09:29:36
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Catalyst-free synthesis of few-layer graphene films on silicon dioxide/Si substrates using ethylene glycol by chemical vapor deposition
摘要： Catalyst-free growth of graphene directly on dielectric substrates is a challenging work for graphene-based electronics. In this paper, a simple method to synthesize large area few layer graphene films on silicon dioxide/Si substrates by chemical vapor deposition is reported. A novel liquid carbon source (ethylene glycol) is used, without any catalysts. The obtained graphene films are characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy. The field effect transistor with graphene film as channel material is fabricated, and the carrier mobility is 707 cm2/V.S. This work offers a new strategy to directly grow graphene on silicon dioxide/Si substrates, and the as-synthesized graphene films may have potential applications in sensors, conductive films, electronic devices, etc.
关键词： Field effect transistor,Synthesis,Catalyst-free,Graphene,Ethylene glycol
更新于2025-09-09 09:28:46