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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Nonlinear Microscopy of Lead Iodide Nanosheets
摘要： Lead iodide (PbI2) is a layered material with unique optical and electrical properties, including direct bandgap in the bulk and a layered crystalline structure, consisting of close-packed Pb atoms sandwiched between two layers of Iodine atoms. Compared to the widely-studied TMDCs, 2D PbI2 is a new type of halide semiconductors with a relatively larger visible bandgap (Eg ～ 2.4 eV) which endows its distinct optical properties. Despite being studied for decades and being used as a precursor for perovskite materials, the recently developed PbI2 nanosheets have shown a great promise for high-performance optoelectronic devices, such as ?exible photodetectors and nanolasers. Such 2D nanosheets also show a great potential for low-dimensional nonlinear optical devices, However, their nonlinear properties are still unexplored, while novel applications of PbI2 nanosheets require careful characterization of their crystalline structure, thickness and nonlinearity. Here we demonstrate the nonlinear microscopy of PbI2 nanosheets using the polarization and thickness dependence of the second harmonic generation (SHG) and third harmonic generation (THG) from solution-grown nanosheets. Our measurements allow to precisely determine their thickness and crystalline orientation with a non-invasive optical technique.
关键词： third harmonic generation,nonlinear microscopy,Lead iodide,second harmonic generation,nanosheets
更新于2025-09-11 14:15:04
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Bacteria-assisted synthesis of nanosheets-assembled TiO2 hierarchical architectures for constructing TiO2-based composites for photocatalytic and electrocatalytic application
摘要： Synthesis and application of three-dimensional TiO2 hierarchical architectures are one of the major priorities in the research and development of TiO2 catalysts. Using bacteria as template and reactor, a bioinspired strategy was developed in the present study to synthesize nanosheets-assembled TiO2 hierarchical architectures (N-TiO2-HA) and relative composites for photocatalytic and electrocatalytic application. In the first part of this work, three kinds of bacteria were used for the synthesis of N-TiO2-HA with satisfactory mono-dispersity, and the growth mechanism was investigated. In the second part, the porous TiO2 hollow spheres (P-TiO2-HS), which were obtained by calcining N-TiO2-HA at 750 oC in air, were incorporated with MIL-101(Fe) to improve the visible-light photocatalytic efficiency. The results of photo-Fenton assisted degradation of rhodamine B and ciprofloxacin indicate that the synthesized composites have excellent visible-light photocatalytic activity. In the third part, the nanosheets-assembled TiO2-carbon hollow spheres (N-TiO2-C-HS), which were obtained by calcining N-TiO2-HA at 750 oC in argon atmosphere, were electrodeposited with Pt for electrocatalytic oxidation of methanol. The electrochemical measurements show that Pt-deposited N-TiO2-C-HS have better electrocatalytic activity, stability, and tolerance to CO poisoning than commercial Pt/C catalysts.
关键词： nanosheets,TiO2 hierarchical architectures,photocatalysis,bacteria,electrocatalytic oxidation of methanol
更新于2025-09-11 14:15:04
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Hydrogen Plasma–Treated MoSe2 Nanosheets Enhance the Efficiency and Stability of Organic Photovoltaics
摘要： In this paper we report the effect on the power conversion efficiency (PCE) and stability of photovoltaic devices after incorporating hydrogenated two-dimensional (2D) MoSe2 nanosheets into the active layer of bulk heterojunction (BHJ) organic photovoltaics (OPV). The surface properties of 2D MoSe2 nanosheets largely affect their dispersion in the active layer blend and, thus, influence the carrier mobility, PCE, and stability of corresponding devices. We treated MoSe2 nanosheets with hydrogen plasma and investigated their influence on the polymer packing and fullerene domain size of the active layer. For the optimized devices incorporating 37.5 wt% of untreated MoSe2, we obtained a champion PCE of 9.82%, compared with the champion reference PCE of approximately 9%. After incorporating the hydrogen plasma–treated MoSe2 nanosheets, we achieved a champion PCE of 10.44%—a relative increase of 16% over that of the reference device prepared without MoSe2 nanosheets. This PCE is the one of the highest ever reported for OPVs incorporating 2D materials. We attribute this large enhancement to the enhanced exciton generation and dissociation at the MoSe2–fullerene interface and, consequently, the balanced charge carrier mobility. The device incorporating the MoSe2 nanosheets maintained 70% of its initial PCE after heat-treatment at 100 °C for 1 h; in contrast, the PCE of the reference device decreased to 60% of its initial value—a relative increase in stability of 17% after incorporating these nanosheets. We also incorporated MoSe2 nanosheets (both with and without treatment) into a polymer donor (PBDTTBO)/small molecule (IT-4F) acceptor system. The champion PCEs reached 7.85 and 8.13% for the devices incorporating the MoSe2 nanosheets with and without plasma treatment, respectively—relative increases of 8 and 12%, respectively, over that of the reference. These results should encourage a push toward the implementation of transition metal dichalcogenides to enhance the performances of BHJ OPVs.
关键词： hydrogen plasma treatment,organic photovoltaics,stability,MoSe2 nanosheets,power conversion efficiency
更新于2025-09-11 14:15:04
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Bi4NbO8Cl {001} nanosheets coupled with g-C3N4 as 2D/2D heterojunction for photocatalytic degradation and CO2 reduction
摘要： Photocatalytic activity is largely restricted by insufficient photoabsorption and intense recombination between charge carriers. Here, we first synthesized Bi4NbO8Cl nanosheets with {001} exposing facets by a molten-salt growth method, which shows largely promoted photocatalytic performance for the degradation of tetracycline (TC) and bisphenol A (BPA) in comparison with Bi4NbO8Cl particles obtained by solid-state reaction. The 2D/2D Bi4NbO8Cl/g-C3N4 heterojunction photocatalysts were then fabricated via high-energy ball-milling and post-sintering to realize intimate interfacial interaction. The photocatalytic activity of all the Bi4NbO8Cl/g-C3N4 composites largely enhances compared to Bi4NbO8Cl nanosheets and g-C3N4, also far exceeding the mechanically-mixed Bi4NbO8Cl nanosheets and g-C3N4. The impact of different reaction parameters on the photocatalytic degradation activities was investigated, including catalyst concentration, pH value and TC concentration. In addition, Bi4NbO8Cl/g-C3N4 also presents improved photocatalytic CO2 reduction activity for CO production. The large enhancement on photocatalytic activity of Bi4NbO8Cl/g-C3N4 composites is owing to the synergistic effect of favorable 2D/2D structure and construction of type II heterojunction with intimate interfacial interaction, thus boosting the charge separation. The formation of type II heterojunction was evidenced by selective photo-deposition of Pt and MnOx, which demonstrate that the reductive sites and oxidative sites are on Bi4NbO8Cl nanosheets and g-C3N4, respectively. This work may provide some insights into fabrication of efficient visible-light driven photocatalysts for environmental and energy applications.
关键词： g-C3N4,photodegradation,Bi4NbO8Cl nanosheets,CO2 reduction,heterojunction
更新于2025-09-11 14:15:04
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Hybrid 0D/2D Ni2P quantum dot loaded TiO2(B) nanosheet photothermal catalysts for enhanced hydrogen evolution
摘要： The development of low cost, stable, robust photocatalysts to convert solar energy into hydrogen energy is an important challenge. Here, we describe a simple solvothermal method to successfully fabricate a catalyst with a hybrid 0D/2D Ni2P quantum dot/TiO2(B) nanosheet architecture. HRTEM shows that Ni2P quantum dots about 5 nm in size were dispersed on ultrathin TiO2(B) nanosheets. The optimum photocatalytic H2 evolution rate with 10 wt% Ni2P/TiO2(B) (3.966 mmol g?1 h?1), which was 15 times higher than pure TiO2(B) nanosheets. Significantly, the new catalyst shows high stability and reusability in multiply cycled H2 production runs for a 30 h period. The H2 production rate can be considerably increased furthered by using synergistic photothermal H2 evolution (20.129 mmol g?1 h?1 at 90 °C).
关键词： TiO2(B) nanosheets,Photocatalytic H2 evolution,Ni2P quantum dots,0D/2D architecture,Synergistic photothermal catalysis
更新于2025-09-11 14:15:04
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Ultrathin Co-Co LDHs nanosheets assembled vertically on MXene: 3D nanoarrays for boosted visible-light-driven CO2 reduction
摘要： Converting carbon dioxide (CO2) to multiple energy-rich chemicals by photocatalysis could validly mitigate the severe issues of climate changes and energy shortages. Exploring efficient catalysts for enhancing the performance of CO2 photoreduction is still challenging. Herein, a novel three-dimensional hierarchical Co-Co layered double hydroxide/Ti3C2TX nanosheets (Co-Co LDH/TNS) nanoarray was successfully prepared via an in-situ MOF-derived strategy. This wise design rationally integrates the functional and structural merits of active Co species with conductive MXene to a hierarchical nanoarray architecture composed of ultrathin nanosheets, which can remarkably promote separation of photogenerated charge carriers and accelerate electrons transmission. Benefitting from these features, the hierarchical Co-Co LDH/TNS composites manifest significant enhancement on the CO2-to-CO evolving rate (1.25×104 μmol h?1 g-1) under illumination (>400nm) with a high apparent quantum efficiency (0.92%) and excellent stability. Our work demonstrates that 3D hybrid structure composed of MXene species can serve as promising candidates for CO2 photoreduction, providing fundamental guidance to improve photocatalytic performance by rational engineering of complex hierarchical architecture materials.
关键词： hierarchical structure,electrons transfer,CO2 reduction,photocatalysis,Ti3C2TX nanosheets
更新于2025-09-11 14:15:04
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Synthesis and improved photoluminescence of hexagonal crystals of Li <sub/>2</sub> ZrF <sub/>6</sub> :Mn <sup>4+</sup> for warm WLED application
摘要： Engineering compositions, structures, and defects can endow nanomaterials with optimized catalytic properties. Here, we report that cobalt oxide (CoOx) ultrathin nanosheets (UTNS, ～1.6 nm thick) with a large number of oxygen defects and mixed cobalt valences can be obtained through a facile one-step hydrothermal protocol. The large number of oxygen defects make the ultrathin CoOx nanosheet a superior OER catalyst with low overpotentials of 315 and 365 mV at current densities of 50 and 200 mA cm?2, respectively. The stable framework-like architectures of the UTNS further ensure their high OER activity and durability. Our method represents a facile one-step preparation of CoOx nanostructures with tunable compositions, morphologies, and defects, and thus promotes OER properties. This strategy may find its wider applicability in designing active, robust, and easy-to-obtain catalysts for OER and other electrocatalytic systems.
关键词： ultrathin nanosheets,oxygen evolution reaction,electrocatalysis,hydrothermal synthesis,cobalt oxide
更新于2025-09-11 14:15:04
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Transparent Collision Visualization of Point Clouds Acquired by Laser Scanning
摘要： Exploring two-dimensional (2D) materials with room-temperature ferromagnetism and large perpendicular magnetic anisotropy is highly desirable but challenging. Here, through first-principles calculations, we propose a viable strategy to achieve such materials based on transition metal (TM) embedded borophene nanosheets. Due to electron deficiency, the commonly existent hexagon boron vacancies in various borophene phases serve as intrinsic anchor points for electron-rich transition metals, which not only adsorb strongly upon the vacancies but also favor to be embedded into the vacancies, forming 2D planar hybrid nanosheets. The adsorption-to-embedding transition is feasible thermodynamically and kinetically, owing to its exothermic nature and relatively small kinetic barriers. After embedding, phase transition is further proposed to obtain diverse structures of TM embedded borophenes with versatile magnetic properties. Based on the example of χ3 phase borophene, several ferromagnetic TM embedded borophene nanosheets with high Curie temperature and large perpendicular magnetic anisotropy have been predicted.
关键词： transition metal embedded borophene nanosheets,first-principles calculations,perpendicular magnetic anisotropy,room-temperature ferromagnetism,two-dimensional materials
更新于2025-09-11 14:15:04
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Coupling heterostructure of thickness-controlled nickel oxide nanosheets layer and titanium dioxide nanorod arrays via immersion route for self-powered solid-state ultraviolet photosensor applications
摘要： A coupling heterostructure consisting of nickel oxide nanosheets (NNS) and titanium dioxide nanorod arrays (TNAs) was fabricated for self-powered solid-state ultraviolet (UV) photosensor applications. By controlling the thickness of the NNS layer by via varying the growth time from 1 to 5 h at a deposition temperature of 90 °C, the coupling NNS/TNAs heterojunction films were formed and their structural, optical, electrical and UV photoresponse properties were investigated. The photocurrent measured from the fabricated self-powered UV photosensor was improved by increasing the thickness of NNS from 140 to 170 nm under UV irradiation (365 nm, 750 mWcm?2) at 0 V bias. A maximum photocurrent density of 0.510 mA?cm?2 was achieved for a sample with a NNS thickness of 170 nm and prepared with a 3 h NNS growth time. Our results showed that the fabricated NNS/TNAs heterojunction has potential applications for self-powered UV photosensors.
关键词： TiO2 nanorods,Electronic materials,Semiconductors,Immersion route,Photosensor,NiO nanosheets
更新于2025-09-11 14:15:04
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Producing graphene nanosheets by pulsed laser ablation: Effects of liquid environment
摘要： Effects of liquid environment on the characteristics of graphene nanosheets produced by the laser ablation method have been studied experimentally. The fundamental wavelength of a pulsed Nd:YAG laser at 1064 nm with 7 ns pulse width and 5 Hz repetition rate was employed to irradiate a graphite target in distilled water, liquid nitrogen, alcohol, acetone, and two concentrations of cetyltrimethylammonium bromide. Produced carbon nanostructures were diagnosed using Ultraviolet-Visible-Near Infrared and Fourier transform infrared spectroscopy, x-ray diffraction, Raman spectroscopy, transmission electron microscopy, and field emission scanning electron microscope images. Results show that different carbon nanostructures such as carbon nanoparticles and fluorine, as well as graphene nanosheets were formed in various liquid environments. The size and morphology of nanostructures strongly depends on the liquid environments and, among these liquids, water is the most capable one to produce graphene nanosheets.
关键词： Raman,carbon nanoparticles,graphene nanosheets,graphite,pulsed laser ablation
更新于2025-09-11 14:15:04