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Kinetics of Ion-Exchange Reactions in Hybrid Organic-Inorganic Perovskite Thin Films Studied by In Situ Real-Time X-ray Scattering
摘要： The exchange of ions in hybrid organic-inorganic perovskites with the general formula APbX3 (A = MA, FA; X = I, Cl, Br) is studied in five different systems using in situ real-time grazing incident X-ray diffraction (GIXD). In systems where the organic cation is exchanged, we find a continuous shift of the lattice parameter. The relative shift compared to the pure materials is used to quantify the exchange. Whether or not a conversion is possible, as well as the amount of exchanged cations, depends on the halide used. In the case of the interconversion of MAPbI3 and MAPbCl3, we observe a decay of the diffraction peaks of the original perovskite and the emergence of new peaks corresponding to the structure with the alternative halide. Moreover, we determined the relevant time scales of the growth and decay of the perovskite structures.
关键词： ion-exchange reactions,kinetics,in situ real-time X-ray scattering,thin films,hybrid organic-inorganic perovskites
更新于2025-09-23 15:21:01
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Designer cell-self-implemented labeling of microvesicles in situ with the intracellular-synthesized quantum dots
摘要： Cell-derived microvesicles (MVs) are secreted from almost all kinds of mammalian cells into the extracellular space, and play crucial roles in intercellular communication and transporting biomolecules between cells. However, there is a great challenge for visualizing and monitoring of MVs’ bio-behaviors due to the limitations of existing labeling methods. Herein, we report the first paradigm of designer cell-self-implemented labeling of MVs secreted from living mammalian MCF-7 cells in situ using the intracellular-synthesized fluorescent quantum dots (QDs) during the formation of MVs. By elaborately coupling intracellular biochemical reactions and metabolism pathways, the MCF-7 cells can be illuminated brightly by intracellular-biosynthesized fluorescent CdSe QDs. Simultaneously, intracellular-synthesized QDs can be in situ encapsulated by the secreted MVs budding from the plasma membrane of the fluorescing cells to label the MVs with an efficiency of up to 89.9%. The whole labeling process skillfully combines designer precise cell-tuned intricate synthesis of CdSe QDs with mild in-situ labeling via cell-self-implementation just after feeding the cell with suitable chemicals, which is structure- or function-nondestructive and much more straightforward and milder than those by chemical conjugation or indirect encapsulation with conventional fluorogenic labels.
关键词： quantum dot,cell-derived microvesicles,live cell synthesis,cell-self-implementation,in situ labeling
更新于2025-09-23 15:19:57
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Evaluation of solution processable polymer reduced graphene oxide transparent films as counter electrodes for dye-sensitized solar cells
摘要： This paper reports the synthesis of reduced oxide (RGO) coated polyaniline (PANi) nanocomposites via in-situ emulsion polymerization and its application as counter electrode for dye sensitized solar cells (DSSCs). The synthesized nanocomposites were systematically characterized through Scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform resonance infra-red (FTIR) and Raman spectroscopy indicating the uniform intercalation of polyaniline with reduced graphene oxide. The synergy between RGO and PANi chains owing to the co-doped SDS and H2SO4 leads to the enhanced solubility and improved electrocatalytic activity, that was further confirmed through electrochemical measurements to satisfy the criteria for application as cost effective counter electrode material for scalable DSSC. The fabricated CE was highly transparent and reached the conversion efficiency which is comparable to that of Platinum with a current density of (12.58 mA. cm-2) and (13.11 mA. cm-2) respectively under an illumination of AM 1.5 G (100 mW. cm-2) simulated solar light with an overall photo conversion efficiency of 3.9 %. Thus PANi/RGO based nanocomposites could therefore serve as efficient alternative material to Pt. free CE in DSSC.
关键词： In-situ emulsion polymerization,PANi,DSSC,counter electrode,reduced graphene oxide
更新于2025-09-23 15:19:57
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Structural Evolutions of Vertically-Aligned Two-Dimensional MoS <sub/>2</sub> Layers Revealed by <i>In Situ</i> Heating Transmission Electron Microscopy
摘要： Benefited from a large density of layer edges exposed on the surface, vertically-aligned two-dimensional (2D) molybdenum disulfide (MoS2) layers have recently harvested excellent performances in the field of electrochemical catalysis and chemical sensing. With their increasing versatility for high-temperature demanding applications, it is vital to identify their thermally-driven structural and chemical stability as well as clarify its underlying principle. Despite various ex situ and in situ characterizations on horizontally-aligned 2D MoS2 layers, the direct in situ heating of vertically-aligned 2D MoS2 layers and the real-time observation of their near-atomic scale dynamics have never been approached, leaving their thermal stability poorly understood. Moreover, the geometrical advantage of the surface-exposed vertically-aligned 2D MoS2 layers is anticipated to unveil the structural dynamics of interlayer van der Waals (vdW) gaps and its correlation with thermal energy, unattainable with 2D MoS2 layers in any other geometry. Herein, we report a comprehensive in situ heating TEM study on cleanly transferred vertically-aligned 2D MoS2 layers up to 1000 °C. Several striking phenomena were newly observed in the course of heating: (1) formation and propagation of voids between the domains of vertical 2D MoS2 layers with distinct grain orientations starting at ~875 °C, (2) subsequent decompositions of the 2D MoS2 layers accompanying a formation of Mo nanoparticles at ~950 °C, much lower than the melting temperature of their bulk counterpart, and (3) initiation of decomposition from the surface-exposed 2D layer vertical edge sites, congruently supported by molecular dynamics (MD) simulation. These new findings will offer critical insights into better understanding the thermodynamic principle that governs the structural stability of general vdW 2D crystals as well as providing useful technological guidance for materials design and optimization in their potential high-temperature applications.
关键词： van der Waals gaps,in situ heating,structural evolution,MoS2,two-dimensional,vertically-aligned,transmission electron microscopy,thermal stability,molecular dynamics simulation
更新于2025-09-23 15:19:57
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Transmission IR cell for atmosphere-controlled studies of photoprocesses on powdered high surface area materials
摘要： Up to now, FT-IR spectroscopy remains one of the most effective techniques employed in the research of various heterogeneous processes including catalysis and photocatalysis. Here, the construction of a newly developed cell designed to conduct in situ IR spectroscopic studies of photoprocesses on powdered adsorbents in the transmission mode is presented. The capabilities of this device are illustrated by experimental data on photoinduced processes involving well known photocatalysts such as titanium dioxide. In particular, the kinetics of the UV-induced spectroscopic alterations in the IR spectrum of hydrated TiO2 were obtained and analyzed. Moreover, the photoactivated desorption of carbon monoxide at ambient temperature from the dehydrated TiO2 surface was observed and plausible explanations were proposed.
关键词： photoprocesses,in situ studies,FT-IR spectroscopy,photocatalysis,titanium dioxide
更新于2025-09-23 15:19:57
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A versatile fluorometric in-situ hybridization method for the quantitation of hairpin conformations in DNA self-assembled monolayers
摘要： As the performance of hairpin DNA (hpDNA)-based biosensors is highly dependent on the yield of stem-loop (hairpin) conformations, we report herein a versatile fluorometric in-situ hybridization protocol for examining hpDNA self-assembled monolayers (SAMs) on popularly used biochip substrates. Specifically, the ratio of fluorescence (FL) intensities of hpDNA SAMs (in an array format) before and after hybridization was adapted as the key parameter for performing such a determination. Upon confirming the existence of mixed and tunable DNA conformations in binary deposition solutions and the efficient hybridization of the hairpin strands with target DNA via gel electrophoresis assays, we have tested the fluorometric protocol for determining the coverages of hpDNA in hpDNA/ssDNA SAMs prepared on gold; its accuracy was validated by Exonuclease I (Exo I)-assisted electrochemical quantitation. To further confirm its versatility, this FL protocol was adapted for quantifying hairpin conformations formed on glass and polycarbonate (PC) substrates. The molar ratios of surface-tethered hairpin conformations on the three different substrates were all found to be proportional to but less than that in the binary deposition solutions, and dependent on the substrate morphology. The findings reported herein are beneficial to the construction of highly efficient DNA hairpin-based sensing surfaces, which essentially facilitates the creation of hpDNA-based biosensors with optimal detection performance.
关键词： In-situ hybridization,conformation evaluation,DNA biosensor/biochip,fluorescence microarray,Hairpin DNA
更新于2025-09-23 15:19:57
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Development of ultra-thin doped poly-Si via LPCVD and ex-situ tube diffusion for passivated contact solar cell applications
摘要： Rear side application of polycrystalline silicon (poly-Si) passivated contacts has demonstrated very high efficiencies for single-junction monocrystalline silicon (mono-Si) solar cells. To further improve the device performance, one possible approach is to apply the passivated contact concept to the front side of the solar cell as well. The front side application requires the use of ultra-thin poly-Si layer in order to suppress parasitic absorption. Suitable ex-situ diffusion process should be developed accordingly without damaging the passivation provided by the very thin interface oxide (iOx). In this work, we prepared symmetric lifetime samples of ultra-thin poly-Si (<30 nm) via low pressure chemical vapour deposition (LPCVD) method. Then we studied and optimised the ex-situ POCl3/BBr3 diffusion doping processes. An excellent passivation quality was demonstrated with a high implied open-circuit voltage (iVoc) of up to 730 mV (on symmetric n+ poly-Si lifetime samples) and 700 mV (on symmetric p+ poly-Si lifetime samples). For possible contact formation, we capped the poly-Si with sputter-deposited ZnO:Al, which shows good opto-electrical properties and firing stability at 650 °C.
关键词： Diffusion,ZnO:Al,Ex-situ doping,Ultra-thin poly-Si,Passivated contact
更新于2025-09-23 15:19:57
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Plastic strain localization induced by microstructural gradient in laser cladding repaired structures
摘要： Laser Cladding is an additive manufacturing technology well suited for the repair of complex metallic components. The repair is a two-step process: first, one removes the worn region and then, the initial geometry is reconstructed locally. The aim of this work is to study the influence of the microstructural gradient on the strain localization in repaired structures. More precisely, we perform in-situ SEM tensile tests completed by EBSD observations of the microstructure in the interface neighborhood between the base material and the repaired region. Furthermore, we monitor the evolution of the local plastic strain distribution at the grain level until failure. This is performed by Digital Image Correlation methods and superposition of grains contours and strain maps. The observations of grain size and plasticity are compared with predictions provided by a Hall-Petch model. The study emphasizes the importance of the microstructural gradient in the vicinity of reparation interface, more precisely it reveals that this gradient induce multiaxial strains and that the strain localization phenomenon is governed mainly by a grain size effect.
关键词： Laser Cladding repair,Additive manufacturing,SEM in-situ tests,strain localization,microstructural gradient
更新于2025-09-23 15:19:57
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[IEEE 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Berlin, Germany (2019.6.23-2019.6.27)] 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - In-Situ Transmission Electron Microscopy Coupled with Resonant Microcantilever for Comprehensive Evaluating Sulfurization Performance of Zinc Oxide Nanowires
摘要： This paper reports a new technique with in-situ transmission electron microscopy (in-situ TEM) and resonant microcantilever to comprehensively evaluate sulfurization performance of ZnO nanowires. Herein, in-situ TEM is used to real-time observe the sulfurization process of ZnO nanowires under SO2-contained atmosphere. temperature-varying micro-gravimetric method, thermodynamic interaction between ZnO nanowires and SO2 molecules is quantitatively evaluated by resonant microcantilever. By exposing the ZnO nanowires sample to SO2-contained atmosphere, a thick shell layer of ZnSO3 can be formed onto the surface of ZnO nanowires and a novel core-shell nanowire structure of ZnO@ZnSO3 is obtained finally. According to our comprehensive evaluation results, the ZnO nanowires sample with 100 nm diameter exhibits high reactive to SO2 molecules and is suitable for SO2 capture and storage.
关键词： sulfurization process,ZnO nanowires,thermodynamic parameter extraction,In-situ TEM
更新于2025-09-23 15:19:57
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[IEEE 2019 2nd World Conference on Mechanical Engineering and Intelligent Manufacturing (WCMEIM) - Shanghai, China (2019.11.22-2019.11.24)] 2019 2nd World Conference on Mechanical Engineering and Intelligent Manufacturing (WCMEIM) - Deep Sea Laser Scanning System for Underwater In-Situ Measurement
摘要： In this paper, a novel laser scanning system for deep sea in-situ measurement was developed. Firstly, the main components of the prototype were introduced separately. Then, the performance of the system was tested and analyzed in a tank filled with water with a standard ball bar. Results showed that the laser scanning system in water can achieve high precision. In addition, the prototype was placed in deep sea to verify the performance of the in-situ measurement and the measured targets are well reconstructed.
关键词： high precision,laser scanning system,in-situ measurement,deep sea
更新于2025-09-23 15:19:57