- 标题
- 摘要
- 关键词
- 实验方案
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Position-free monte carlo simulation for arbitrary layered BSDFs
摘要： Real-world materials are often layered: metallic paints, biological tissues, and many more. Variation in the interface and volumetric scattering properties of the layers leads to a rich diversity of material appearances from anisotropic highlights to complex textures and relief patterns. However, simulating light-layer interactions is a challenging problem. Past analytical or numerical solutions either introduce several approximations and limitations, or rely on expensive operations on discretized BSDFs, preventing the ability to freely vary the layer properties spatially. We introduce a new unbiased layered BSDF model based on Monte Carlo simulation, whose only assumption is the layer assumption itself. Our novel position-free path formulation is fundamentally more powerful at constructing light transport paths than generic light transport algorithms applied to the special case of flat layers, since it is based on a product of solid angle instead of area measures, so does not contain the high-variance geometry terms needed in the standard formulation. We introduce two techniques for sampling the position-free path integral, a forward path tracer with next-event estimation and a full bidirectional estimator. We show a number of examples, featuring multiple layers with surface and volumetric scattering, surface and phase function anisotropy, and spatial variation in all parameters.
关键词： BSDF,Monte Carlo integration,layered materials
更新于2025-09-23 15:23:52
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Materials-Informatics-Assisted High-Yield Synthesis of 2D Nanomaterials through Exfoliation
摘要： A variety of inorganic and organic nanosheets with characteristic structures and properties can be synthesized through exfoliation of layered materials. However, in general, immense time and efforts are required for exploration of exfoliation conditions and characterization of nanosheets. In addition, it is challenging to improve the yield of nanosheets obtained through exfoliation. Here a materials-informatics-assisted high-yield synthesis of nanosheets is proposed, which does not require experience and intuition. Layered composites containing inorganic layers and interlayer organic guests are delaminated into nanosheets in a variety of dispersion media. First, an experimental screening is performed to find efficient exfoliation conditions and obtain a training dataset for the informatics approach. Sparse modeling is then used facilitating the extraction of important factors predicting the yield of nanosheets. High-yield (up to (cid:2)50%) synthesis of nanosheets is demonstrated in unknown systems in a minimum number of experiments. The yield is higher than those typically reported for layered materials. It is expected that the effective combination has potentials for not only discovery of compounds but also structure control of materials.
关键词： sparse modeling,layered materials,exfoliation,2D nanomaterials,materials informatics
更新于2025-09-23 15:22:29
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Free-standing black phosphorus thin films for flexible quasi-solid-state micro-supercapacitors with high volumetric power and energy density
摘要： Micro-supercapacitors (micro-SCs) are significant micro-scale power sources and energy storage components for miniaturized electronic and flexible devices, where electrodes play the key role in determining their electrochemical performance. The efficient intercalation of ions between the stacking layers of 2D layered materials (2DLM) makes them great candidates as thin film electrodes in micro-SCs, where one can achieve much enhanced volumetric capacitance. However, a great challenge is to develop a high-yield production method for high quality 2DLM thin film electrodes. In this work, we have successfully reported a scalable fabrication process for free-standing black phosphorous (BP) thin films, derived from the high quality few-layer BP nanoflakes via a modified electrochemical exfoliation route, for flexible quasi-solid-state micro-SCs (QMSCs). The as-fabricated QMSCs exhibit an excellent stable electrochemical performance at a high scan rate up to 100 V s-1. More importantly, our QMSC device can not only achieve an outstanding energy density of 3.63 mW h cm-3, a remarkable power density of 10.1 W cm-3 and a superior cycle span (94.3% capacity retention even after 50000 cycles), but also deliver the excellent mechanical flexibility is demonstrated by 91.3% capacity retention after 500 mechanical bending cycles. More interesting, to meet the energy density and power density needs for various practical applications, multiple QMSCs can be successfully integrated in parallel or in series, which is demonstrated by lighting up of the red light emitting diode (LED). The BP-based QMSCs can be patterned on a single substrate with flexible photodetectors based the same BP thin film to form a self-powered optoelectronic system.
关键词： thin film,black phosphorous,2D layered materials,micro-supercapacitors,energy storage
更新于2025-09-23 15:22:29
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Photo-induced lattice contraction in layered materials
摘要： Structural and electronic changes induced by optical excitation is a promising technique for functionalization of 2D crystals. Characterizing the effect of excited electronic states on the in-plane covalent bonding network as well as the relatively weaker out-of-plane dispersion interactions is necessary to tune photo-response in these highly anisotropic crystal structures. In-plane atom dynamics was measured using pump-probe experiments and characterized using ab initio simulations, but the effect of electronic excitation on weak out-of-plane van der Waals bonds is less well-studied. We use non-adiabatic quantum molecular dynamics to investigate atomic motion in photoexcited MoS2 bilayers. We observe a strong athermal reduction in the lattice parameter along the out-of-plane direction within 100 fs after electronic excitation, resulting from redistribution of electrons to excited states that have lesser anti-bonding character between layers. This non-trivial behavior of weakly bonded interactions during photoexcitation could have potential applications for modulating properties in materials systems containing non-covalent interactions like layered materials and polymers.
关键词： quantum molecular dynamics,layered materials,MoS2,photo-dynamics,van der Waals
更新于2025-09-23 15:22:29
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Highly efficient white-LED-light-driven photocatalytic hydrogen production using highly crystalline ZnFe2O4/MoS2 nanocomposites
摘要： Designing efficient photocatalytic systems for hydrogen evolution is extremely important from the viewpoint of the energy crisis. Highly crystalline heterostructure catalysts have been established, considering their interface electric field effect and structural features, which can help improve their photocatalytic hydrogen-production activity. In this study, we fabricated a highly crystalline heterojunction consisting of ZnFe2O4 nanobricks anchored onto 2D molybdenum disulfide (MoS2) nanosheets (i.e., ZnFe2O4/MoS2) via a hydrothermal approach. The optimized ZnFe2O4/MoS2 photocatalyst, with a ZnFe2O4 content of 7.5 wt%, exhibited a high hydrogen-production rate of 142.1 mmol h?1 g?1, which was 10.3 times greater than that for the pristine ZnFe2O4 under identical conditions. The photoelectrochemical results revealed that the ZnFe2O4/MoS2 heterojunction considerably diminished the recombination of electrons and holes and promoted efficient charge transfer. Subsequently, the plausible Z-scheme mechanism for photocatalytic hydrogen production under white-LED light irradiation was discussed. Additionally, the influence of cocatalysts on the photocatalytic hydrogen evolution for the ZnFe2O4/MoS2 heterostructure was investigated. This work has demonstrated a simplified coupling of one-dimensional or zero-dimensional structures with 2D nanosheets for improving the photocatalytic hydrogen production activity as well as confirmed that MoS2 is a viable substitute for precious metal-free photocatalysis.
关键词： Photocatalytic hydrogen production,Layered materials,MoS2,Photocatalysts,Heterojunction
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 5th International Conference for Convergence in Technology (I2CT) - Bombay, India (2019.3.29-2019.3.31)] 2019 IEEE 5th International Conference for Convergence in Technology (I2CT) - Growth of Different Microstructure of MoS <sub/>2</sub> through Controlled Processing Parameters of Chemical Vapor Deposition Method
摘要： The anisotropic bonding in layered materials crystallize to form different structure such as smooth films, nanotubes, and fullerene-like nanoparticles. Here, the growth of different microstructure of MoS2 via chemical vapor deposition (CVD) method through controlled processing parameters is reported. Scanning electron microscopy and Raman spectroscopy ascertained the MoS2 on insulating substrate (SiO2/Si). It was observed that poor sulfur environment and slow vapor flow were unable to induce complete transition from MoO3-x to MoS2 and formed intermediate MoO2.The MoS2 and MoO2/MoS2 heterostructure were synthesized via single step. In addition, by adjustment of heating rate with temperature of centre zone and vapor flow, flower like structure of MoS2 was achieved.
关键词： Sulfurization,CVD,MoS2,Layered materials,2D materials
更新于2025-09-19 17:13:59
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Pyrolysis‐Synthesized g‐C <sub/>3</sub> N <sub/>4</sub> /Nb <sub/>2</sub> O <sub/>5</sub> Nanocomposite for Enhanced Photocatalytic Activity under White LED Light Irradiation
摘要： The design and fabrication of highly active visible-light-driven photocatalysts have been received considerable attention in recent years. However, individual component-based photocatalysts are limited in their use because of the high recombination of photoinduced carriers and poor chemical stability. Herein, the Z-scheme-originated photocatalytic activity of in-situ deposited Nb2O5 NPs on the plane surface of carbon nitride (g-C3N4) nanosheets (i. e. CN-NbO) heterostructures was studied using a simple thermal pyrolysis method. The as-synthesized photocatalysts distinctly manifested efficient white light-emitting diode (LED) irradiation toward organic malachite green (MG) dye degradation and photocatalytic hydrogen generation. The CN-NbO heterostructure showed a faster degradation rate of the MG dye and a higher photocatalytic hydrogen evolution rate. In addition, the plausible Z-scheme photocatalytic mechanism for photocatalytic hydrogen production under LED light irradiation was discussed. Photoelectrochemcial studies showed that the superior photoactivity of CN-NbO heterostructure is mainly a result of the suitable alignment of the band edge positions, which diminish carrier recombination and facilitate efficient interfacial charge transport at their interface. This study provides an ideal method for in-situ fabrication of novel two dimensional/one dimension-based photocatalysts with high activity and stable performance for photocatalytic hydrogen generation.
关键词： Dye degradation,Hydrogen evolution,Nanoparticles,Photocatalyst,LED irradiation,Layered materials
更新于2025-09-11 14:15:04
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Biodegradable Bi <sub/>2</sub> O <sub/>2</sub> Se Quantum Dots for Photoacoustic Imaging-Guided Cancer Photothermal Therapy
摘要： As new 2D layered nanomaterials, Bi2O2Se nanoplates have unique semiconducting properties that can benefit biomedical applications. Herein, a facile top-down approach for the synthesis of Bi2O2Se quantum dots (QDs) in a solution is described. The Bi2O2Se QDs with a size of 3.8 nm and thickness of 1.9 nm exhibit a high photothermal conversion coefficient of 35.7% and good photothermal stability. In vitro and in vivo assessments demonstrate that the Bi2O2Se QDs possess excellent photoacoustic (PA) performance and photothermal therapy (PTT) efficiency. After systemic administration, the Bi2O2Se QDs accumulate passively in tumors enabling efficient PA imaging of the entire tumors to facilitate imaging-guided PTT without obvious toxicity. Furthermore, the Bi2O2Se QDs which exhibit degradability in aqueous media not only have sufficient stability during in vivo circulation to perform the designed therapeutic functions, but also can be discharged harmlessly from the body afterward. The results reveal the great potential of Bi2O2Se QDs as a biodegradable multifunctional agent in medical applications.
关键词： biodegradable,Bi2O2Se,2D layered materials,photothermal agents,photoacoustic imaging
更新于2025-09-11 14:15:04
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Revealing the Spectrum of Unknown Layered Materials with Super-Human Predictive Abilities
摘要： We discover the chemical composition of over 1000 materials that are likely to exhibit layered and two-dimensional phases but have yet to be synthesized. This includes two materials our calculations indicate can exist in distinct structures with different band gaps, expanding the short list of two-dimensional phase change materials. While databases of over 1000 layered materials have been reported, we provide the first full database of materials that are likely layered but yet to be synthesized, providing a roadmap for the synthesis community. We accomplish this by combining physics with machine learning on experimentally obtained data and verify a subset of candidates using density functional theory. We find our model performs five times better than practitioners in the field at identifying layered materials and is comparable or better than professional solid-state chemists. Finally, we find that semi-supervised learning can offer benefits for materials design where labels for some of the materials are unknown.
关键词： two-dimensional materials,machine learning,materials discovery,density functional theory,layered materials
更新于2025-09-09 09:28:46
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Photonic Nanostructures from Hexagonal Boron Nitride
摘要： Growing interest in devices based on layered van der Waals (vdW) materials is motivating the development of new nanofabrication methods. Hexagonal boron nitride (hBN) is one of the most promising materials for studies of quantum photonics and phonon polaritonics. A promising nanofabrication process used to fabricate several hBN photonic devices using a hybrid reactive ion etching (RIE) and electron beam-induced etching (EBIE) technique is reported in detail here. The shortcomings and benefits of RIE and EBIE are highlighted and the utility of the hybrid approach for the fabrication of suspended and supported device structures with nanoscale features and highly vertical sidewalls are demonstrated. Functionality of the fabricated devices is proven by measurements of high-quality cavity optical modes (Q ≈ 1500). This nanofabrication approach constitutes an advance toward an integrated, monolithic quantum photonics platform based on hBN and other layered vdW materials.
关键词： hexagonal boron nitride,photonic devices,nanofabrication,nanophotonics,layered materials
更新于2025-09-04 15:30:14