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Hybrid of quantum dots for interfacial tension reduction and reservoir alteration wettability for enhanced oil recovery (EOR)
摘要： Nanoparticle stabilized emulsions in enhanced oil recovery are more attractive and practical than conventional emulsions which stabilized by colloidal particles and different surfactants due to their advantages and special characteristics such as high stability in harsh condition, move long distance in reservoirs without high retention due to small size of nanoparticles. Only one third of original oil in place (OIP) is usually produced and two third of oil in place will be trapped to reservoir rockthus suitable chemical enhanced oil recovery (C-EOR) methods should be used. In this research, we have suggested a novel, economical and commercial method for synthesis N-doped graphene quantum dots (N-GQDs)/MoS2 quantum dots (MQDs) nanohybrids for preparing different percentage of Nanoemulsions which can reduce alterfacial tension significantly so it can used for Enhanced Oil Recovery (EOR) application. MoO3 material was used as a base of MQDs. MQDs was synthesized via exfoliation of MoS2 nanoparticles by Butyl lithium under N2 atmosphere condition. N-GQDs were synthesized by citric acid and urea materials via hydrothermal method. GQDs/MQDs were prepared via a simple sol-gel method for 5 h string. Synthetic materials were characterized with X-ray diffraction (XRD), Fourier transform infrared (FT-IR), UV–visible absorption, Scanning Microscopic Electron (SEM), EDX profile and mapping, Transmission electron microscopy (TEM), High Resolution Transmission electron microscopy (HRTEM) and differential scanning calorimetry (DSC). Then, emulsions were prepared with two different cationic and anionic surfactants and the stability and morphology of emulsion droplets were investigated in condition close to reservoir environment. Our results show that 10% GQDs/MQDs in cationic surfactant and 50% GQDs/MQDs in anionic surfactant have good stability and very small and fine emulsion droplets in simulated reservoir conditions in laboratory. The Interfacial Tension (IFT) measurement shows N70% improvement which indicates the high ability of these nanohybrids in reducing the surface tension than previous nanohybrids. Contact angle values show that these nanohybrids can alter the wettability of reservoir rock from oil-wet to water-wet so the trapped oil in the porous region of rock can be easily extracted in the presence of a layer of these nanohybrids. Furthermore, according to the results of altering the density and viscosity of nanohybrids, these are not as limiting parameters and only about 1% increasing observed for density and viscosity, respectively. Coreflooding test revealed the high oil recovery efficiency (22%) at very low nanofluid concentration (0.01 wt%).
关键词： Molybdenum disulfide quantum dots,Graphene quantum dots,Nanohybrids emulsion,Enhanced oil recovery (EOR),Quantum dot hybrids,Rock reservoir alteration wettability
更新于2025-09-23 15:21:01
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High Emission Quantum Yield Tb <sup>3+</sup> -Activated Organic-Inorganic Hybrids for UV-Down-Shifting Green Light-Emitting Diodes
摘要： Solid-state light-emitting diodes (LEDs) are driving the lighting industry towards efficient and environmentally friendly lighting and displays. Current challenges encompass efficient and low-cost down-shifting phosphors with tuned emission colors. Green light lies on the low-loss optical transmission window in plastic optical fibers and plays a special role in human and plants circadian rhythm regulation. Moreover, green-emitting phosphors may suppress the ‘green gap’ found in semiconductor-based LEDs. In this work, a UV-photostable Tb(NaI)3(H2O)2, with (1-ethyl-1,4-dihydro-7-methyl-4-oxo-1,8-NaI= nalidixic naftiridine-3-carboxylic acid), was incorporated into tripodal organic-inorganic hybrid materials. The hybrid hosts boost the absolute emission quantum yield from ~0.11 (isolated complex) to ~0.82 (doped hybrid), being the largest value reported for Tb3+-based hybrid phosphors. A green-emitting LED was fabricated by coating a near-UV LED (365 nm) with a Tb3+-activated organic-inorganic hybrid showing pure-green light with Commission International de l’Eclairage color coordinates and an efficacy value of (0.33, 0.59) and 1.3 lm·W?1, respectively.
关键词： near-UV light-emitting diodes,green light-emitting diodes,lanthanides,solid-state lighting,organic-inorganic hybrids
更新于2025-09-23 15:21:01
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Two-dimensional Hybrid Halide Perovskites: Principles and Prom-ises
摘要： Hybrid halide perovskites have become the “next big thing” in emerging semiconductor materials as the past decade witnessed their successful application in high-performance photovoltaics. This resurgence has seen enormous and widespread development of the three-dimensional (3D) perovskites, spearheaded by CH3NH3PbI3. The next generation of halide perovskites, however, is characterized by reduced dimensionality perovskites, emphasizing on the two-dimensional (2D) perovskite derivatives which expand as a more diverse subgroup of semiconducting hybrids that possesses even higher tunability and excellent photophysical properties. In this perspective, we begin with a historical flashback that traces back to early reports before the “perovskite fever” and we follow this original work to its fruition in the present day, where 2D halide perovskites are on the spotlight of current research, thriving on several aspects of high-performance optoelectronics. We approach the evolution of 2D halide perovskites from a structural perspective, providing a classification for the diverse structure-types of the materials, which largely dictate the unusual physical properties observed. We sort out the 2D hybrid halide perovskite based on two key components: the inorganic layers and their modification and the organic cation diversity. As these two heterogeneous components blend, either by synthetic manipulation (shuffling the organic cations or inorganic elements) or by external stimuli (temperature and pressure), the modular perovskite structure evolves to construct crystallographically defined quantum wells (QW). The complex electronic structure that arises is sensitive to the structural features that could be in turn used as a knob to control the dielectric and optical properties the QWs. We conclude this perspective with the most notable optoelectronic device achievements that have been demonstrated to date with an eye towards future material discovery and potential technological developments.
关键词： two-dimensional (2D) perovskite derivatives,optoelectronic devices,quantum wells (QW),Hybrid halide perovskites,semiconducting hybrids
更新于2025-09-23 15:21:01
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Effect on Local Structure and Phase Transition of Perovskite-Type [N(CH3)4]2Zn1-xCuxBr4 (x?=?0, 0.5, 0.7, and 1) Crystals with the Various Doping of Cu2+ Ions
摘要： This study focused on how the local structures in pure [N(CH3)4]2ZnBr4 crystal are affected by the partial replacement of Zn2+ ions with Cu2+ ions. The structures and phase transition temperatures TC of perovskite-type [N(CH3)4]2Zn1-xCuxBr4 (x = 0, 0.5, 0.7, and 1) mixed crystals were almost unchanged by the partial doping of Cu2+ ions. The environments for the local structures of [N(CH3)4]2Zn1-xCuxBr4 mixed systems were studied according to differences in the chemical shifts of the 1H magic angle spinning (MAS) NMR, 13C cross-polarization (CP)/MAS NMR, and 14N NMR spectra. The 1H and 13C NMR results showed that the local environments of 1H and 13C nuclei near TC are not affected by substituting Zn2+ ions with Cu2+ ions, whereas the 14N NMR results showed that the local environment is affected near TC. Consequently, the main indicators of the phase transition in [N(CH3)4]2Zn1-xCuxBr4 are related to the ferroelastic characteristics with different orientations.
关键词： phase transition,ferroelastic characteristics,NMR spectroscopy,perovskite structures,Metal-organic hybrids
更新于2025-09-23 15:21:01
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Plasmon-Assisted Energy Transfer in Hybrid Nanosystems
摘要： While direct optical excitation of carbon nanotubes activates only the tube species strictly matching the excitation source, excitation energy transfer processes provide a single excitation channel for all the nanotubes species in a sample. The requirement of an overlap between donor emission and acceptor absorption limits the poll of donors able to trasfer their excitation to the tubes, leaving the high-energy part of the solar spectrum excluded from such processes. Here it is shown that the grafting of small metal nano-particles to the tubes alters those rules, enabling energy transfer process from molecules for which the standard energy transfer process is strongly suppressed. The onset of an energy transfer band in the UV/blue spectral region is demonstrated for an hybrid gold-pyrene-nanotube system, yielding collective emission from all the tubes present in our samples upon excitation of pyrene.
关键词： gold nanoparticles,pyrene dye,carbon nanotubes,plasmonic hybrids,energy transfer
更新于2025-09-23 15:21:01
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Hybrid Nanostructures of 2D CdSe Nanoplatelets for High-Performance Photodetector Using Charge Transfer Process
摘要： Two-dimensional (2D) semiconductor colloidal nanoplatelets (NPLs) have shown great potential as light-harvesting materials due to their advanced optical properties. Here, we have designed hybrid nanostructures of 2D CdSe nanoplatelets with phenothiazine (PTZ) for high-performance photodetector with varying thickness of CdSe NPLs by controlling charge transfer process. Significant photoluminescence quenching and the shortening of the average decay time of CdSe NPLs in presence of PTZ reveal the charge transfer process. Transient absorption (TA) spectroscopic analysis reveals the hot carrier cooling dynamics varies with changing the thickness of monolayers (ML) of CdSe NPLs. Furthermore, the slow exciton recombination of CdSe NPLs in presence of PTZ indicates the efficient charge separation. The optimized CdSe NPLs-PTZ hybrid exhibits a significant enhancement of photocurrent (~4.7×103 fold photo-to-dark current ratio) as compared to pure 3 ML CdSe NPLs (~10 fold) at the applied voltage of 1.5V. The measured external quantum efficiency, maximum detectivity and response time for the optimized hybrid are found to be ~40%, 4×1011 Jones and 107 milliseconds, with the responsivity value of 160 mA/W. These highly efficient measured parameters clearly suggest that CdSe NPLs-PTZ hybrid systems are promising alternate for ultrasensitive photodetector.
关键词： 2D colloidal nanoplatelets,photodetectors,hole transfer,hybrids,photocurrent
更新于2025-09-23 15:19:57
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Three-dimensional Lead Iodide Perovskitoid Hybrids with High X-ray Photoresponse
摘要： Large organic A cations cannot stabilize the 3D perovskite AMX3 structure because they cannot be accommodated in the cubo-octhedral cage (do not follow the Goldschmidt tolerance factor rule), and they generally template low-dimensional structures. Here we report that the large di-cation aminomethylpyridinium (AMPY), can template novel 3D structures which resemble conventional perovskites. They have the formula (xAMPY)M2I6 (x = 3 or 4, M = Sn2+ or Pb2+) which is doubled the AMX3 formula. However, because of the steric requirement of the Goldschmidt tolerance factor rule, it is impossible for (xAMPY)M2I6 to form proper perovskite structures. Instead, a combination of corner-sharing and edge-sharing connectivity is adopted in these compounds leading to the new 3D structures. DFT calculations reveal that the compounds are indirect-bandgap semiconductors with direct bandgaps presenting at slightly higher energies and dispersive electronic bands. The bandgaps of the Sn and Pb compounds are ~ 1.7 eV and 2.0 eV, respectively, which is slightly higher than the corresponding AMI3 3D perovskites. The Raman spectra for the compounds are diffuse, with a broad rising central peak at very low frequencies around 0 cm-1, a feature that is characteristic of dynamical lattices, highly anharmonic, and dissipative vibrations very similar to the 3D AMX3 perovskites. Devices of (3AMPY)Pb2I6 crystals exhibit clear photoresponse under ambient light without applied bias, reflecting a high carrier mobility (μ) and long carrier lifetime (τ). The devices also exhibit sizable X-ray generated photocurrent with a high μτ product of ~1.2×10-4 cm2 /V and an X-ray sensitivity of 207 μC·Gy-1·cm-2.
关键词： Metal halide hybrids,mixed cations,photoresponse,X-ray detector,anomalous bandgap behavior
更新于2025-09-23 15:19:57
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Boosting the photocatalytic performances of covalent organic frameworks enabled by spatial modulation of plasmonic nanocrystals
摘要： Plasmonic Au nanocrystals (NCs) are incorporated into covalent organic frameworks (COFs) with precisely modulated distributions to improve the efficiency of electron-hole separation covalent reactions and assembly of NCs, sparsely dispersed Au NCs (AuSP/COFs) or the close packed ones (AuCP/COFs) in COFs are fabricated, in which the contributions of electron acceptors/cocatalysts on the catalytic properties of Au/COFs composites are addressed by EPR, PL, phenacyl bromide (conversion >99%, selectivity of acetophenone ~92.8%) under visible light irradiation, which are associated with accelerated electron transfer, increased available Au/COFs and optimize the charge-carrier utilization. Specifically, through balancing the rate of dynamic Schottky junctions and boosted interfacial reaction kinetics. Overall, this work contributes to the fundamental understanding of the how spatial distributions of NCs in COFs affect the photocatalytic performances.
关键词： metallic nanocrystals,heterojunctions,covalent organic frameworks,photocatalysis,inorganic/organic hybrids
更新于2025-09-23 15:19:57
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Laser-based surface pre-treatment for metal-plastic hybrids using a new process strategy
摘要： In order to join metal-plastic hybrid parts so as to achieve lightweight constructions, innovative joining technologies are essential. For this, thermal joining is a promising approach due to the absence of any joining agent. The joint strength can be increased by surface pre-treatment of the metal with continuous wave laser radiation. Large joining areas, however, are challenging in terms of productivity, efficiency and geometrical flexibility when beam trajectories, which can be easily combined with on-the-fly processing. More precisely, a load direction, and causes lower thermal distortion of the metal sheet than using conventional processing of large areas. In this context, the resulting topography of the metal was analyzed circularly oscillating laser focal spot is geometrically independent of every possible in-plane with respect to the surface roughness and a design criterion was mathematically derived and experimentally validated. Additionally, the joint strength was compared to the strength using conventional beam trajectories. A more promising approach is the use of continuous with a carbon-fiber-reinforced thermoset. The laser-based pre-treatment using the circularly oscillating laser focal spot led to a similar joint strength, while being more productive when resulting from conventional beam trajectories. For verification, steel substrates were joined combined with on-the-fly processing, compared to conventional structuring trajectories.
关键词： surface pre-treatment,continuous wave laser radiation,metal-plastic hybrids,thermal joining
更新于2025-09-23 15:19:57
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Low dimensional metal halide perovskites and hybrids
摘要： Organic-inorganic metal halide hybrids are an important class of crystalline materials with exceptional structural and property tunability. Recently metal halide perovskites with ABX3 structure have been extensively investigated as new generation semiconductors for various optoelectronic devices, including photovoltaic cells, light emitting diodes, photodetectors, and lasers, for their exceptional optical and electronic properties. By controlling the morphological dimensionality, low dimensional metal halide perovskites, including 2D perovskite nanoplatelets, 1D perovskite nanowires, and 0D perovskite quantum dots, have been developed to exhibit distinct properties from their bulk counterparts, due to quantum size effects. Besides ABX3 perovskites, organic-inorganic metal halide hybrids, containing the same fundamental building block of metal halide octahedra (BX6), can also be assembled to possess other types of crystallographic structures. Using appropriate organic and inorganic components, low dimensional organic-inorganic metal halide hybrids with 2D, quasi-2D, corrugated-2D, 1D, and 0D structures at the molecular level have been developed and studied. Due to the strong quantum confinement and site isolation, these low dimensional metal halide hybrids at the molecular level exhibit remarkable and unique properties that are significantly different from those of ABX3 perovskites. In light of the rapid development of low dimensional metal halide perovskites and hybrids, it is indeed timely to review the recent progress in these areas. Also, there is a need to clarify the difference between morphological low dimensional metal halide perovskites and molecular level low dimensional metal halide hybrids, as currently the terminologies of low dimensional perovskites are not appropriately used in many cases. In this review article, we discuss the synthesis, characterization, application, and computational studies of low dimensional metal halide perovskites and hybrids.
关键词： Optoelectronics,Halide Perovskites,Nanomaterials,Low dimensionality,Organic metal halide hybrids
更新于2025-09-23 15:19:57