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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - A Comparison of Hyper-Sharpening Algorithms for Fusing VNIR and SWIR Bands of WorldView-3 Satellite Imagery
摘要： In this study, visible and near-infrared (VNIR) and shortwave infrared (SWIR) bands of WorldView-3 imagery were sharpened to the spatial resolution of a panchromatic image. We performed experiments on three band schemes according to a method for generating an optimal panchromatic image. Various pan-sharpening algorithms based on component-substitution (CS) and multi-resolution analysis (MRA) were applied to each band scheme. Quantitative and qualitative assessments were performed using the quality indices and visual inspection.
关键词： selected and synthesized band scheme,multiple linear regression,WorldView-3 sharpening
更新于2025-09-09 09:28:46
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Constrained two-stream algorithm for calculating aerosol light absorption coefficient from the Particle Soot Absorption Photometer
摘要： We present a new correction scheme for filter-based absorption photometers based on a constrained two-stream (CTS) radiative transfer model and experimental calibrations. The two-stream model was initialized using experimentally accessible optical parameters of the filter. Experimental calibrations were taken from the literature and from dedicated experiments for the present manuscript. Uncertainties in the model and calibration experiments are discussed and uncertainties for retrieval of absorption coefficients are derived. For single-scattering albedos lower than 0.8, the new CTS method and also other correction schemes suffer from the uncertainty in calibration experiments, with an uncertainty of about 20 % in the absorption coefficient. For high single-scattering albedos, the CTS correction significantly reduces errors. At a single-scattering albedo of about 0.98 the error can be reduced to 30 %, whereas errors using the Bond correction (Bond et al., 1999) are up to 100 %. The correction scheme was tested using data from an independent experiment. The tests confirm the modeled performance of the correction scheme when comparing the CTS method to other established correction methods.
关键词： filter-based absorption photometers,radiative transfer,correction scheme,constrained two-stream model,aerosol light absorption
更新于2025-09-09 09:28:46
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A facile method for regulating the charge transfer route of WO3/CdS in high-efficiency hydrogen production
摘要： In order to intrinsically boost the photocatalytic performance of WO3/CdS, the charge transfer route can be modulated from conventional type-Ⅱ to Z-scheme by incorporating of hydrogen ions into WO3/CdS to form H0.53WO3/CdS. This work indicates that only when charge transfer of WO3/CdS is type-Ⅱ, can H0.53WO3/CdS composite be formed in-situ. Subsequently, the Z-scheme photocatalytic mechanism plays its prominent roles in gradually improving photocatalytic H2 evolution performance. H0.53WO3/CdS has high photocatalytic activity for hydrogen production, which is much higher than that of WO3/CdS. This work will provides an in-depth understanding of charge separation and transfer processes and steer charge flow in a Z-scheme manner for efficient solar-to-chemical energy applications.
关键词： type-Ⅱ,Z-scheme,H0.53WO3/CdS,charge transfer route,photochromism
更新于2025-09-09 09:28:46
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Interfacial Optimization of g-C3N4-based Z-Scheme Heterojunction toward Synergistic Enhancement of Solar-Driven Photocatalytic Oxygen Evolution
摘要： Exploring active catalyst materials for solar-driven photocatalytic water splitting into oxygen has proven extremely challenging, mostly due to poor oxygen-evolving efficiency originating from intrinsically sluggish oxygen evolution reaction (OER) kinetics. Ag3PO4 has been actively pursued as a promising photocatalyst for oxygen evolution from water-splitting. However, its low OER efficiency is a long standing problem. Both the construction of Z-scheme Ag3PO4-based composite photocatalytic systems and the optimization of surface morphology and interfacial contact in heterojunctions photocatalysts would be beneficial for boosting OER efficiency. Here we report on the fabrication of Ag3PO4/fish scale-like graphitic carbon nitride (g-C3N4) sheet composites with well-defined heterostructures and intimate interfacial contact driven by electrostatic assembly. The Ag3PO4/modified g-C3N4 composites photocatalyst reveals significantly enhanced oxygen-evolving activity under light-emitting diode (LED) illumination. Effective surface modification of g-C3N4, strong interfacial interactions between two semiconductors and tandem Z-scheme-type pathway for more efficient charge transfer synergistically accelerates the redox capability of Ag3PO4 for OER. This work may provide new insights into the design and construction of high-performance solar-driven Z-scheme photocatalytic water splitting systems.
关键词： water splitting,Z-scheme,photocatalytic oxygen evolution,g-C3N4,Ag3PO4
更新于2025-09-09 09:28:46
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Construction of two dimensional composite derived from TiO2 and SnS2 for enhanced photocatalytic reduction of CO2 into CH4
摘要： Photocatalytic reduction of CO2 does effectively mitigate the concern of environment issue and energy shortage. As one of the effective techniques for improving photocatalytic performance, highly efficient compounding between semiconductor and cocatalyst is capable of inhibiting electrons and holes recombination. Herein, we build a 2D-2D heterojunction photocatalyst (SnS2/TiO2) to proffer a highly ameliorated effect on the photocatalysis. The catalyst was prepared by hydrothermally depositing ultrathin SnS2 nanosheets onto TiO2 nanosheets. The prepared composite is systematically analyzed and confirmed by the corresponding characterizations. Further practical application of the as-synthesized catalysts demonstrates that when the loaded amount of SnS2 is 5wt%, the activity of 2D-2D SnS2/TiO2 catalyst exhibits the optimum catalytic activity with the CH4 yield of 23μmol/g, which is 20, 10 and 9 times greater than that conducted by P25, TiO2 nanosheet and SnS2 nanosheet, respectively. According to the PL, PEC and TEM characterization, along with the increment of the contact interface between the two components, the combination of electrons and holes is greatly reduced.
关键词： Z-Scheme,Co-exposed,Photocatalytic reduction,2D-2D heterojunction
更新于2025-09-09 09:28:46
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Facial construction of defected NiO/TiO2 with Z-scheme charge transfer for enhanced photocatalytic performance
摘要： Here we report a defected NiO/TiO2 composite (NiO/TiO2-OV) fabricated by a two-step hydrothermal method with the followed one-step calcination, which induced the in situ generation of Ti3+ and oxygen vacancies, coupled with the construction of a direct Z-scheme band structure. The NiO/TiO2-OV catalyst exhibited a substantially improved performance in the photodegradation of organic pollutant and photocatalytic hydrogen evolution reaction (HER). The sensitization by narrow bandgap semiconductor of NiO enhanced the light response of catalysts. More importantly, the intrinsic defects, the Ti3+ and oxygen vacancies, acted as the mid-gap state in TiO2, and resulted in the direct Z-scheme charge transfer between the Ti3+/oxygen vacancies state and the valance band (VB) of NiO to suppress the recombination of photogenerated electrons and holes. Meanwhile, the realignment of band structure caused by constructing NiO/TiO2 heterojunction made the photogenerated carries more active in the photocatalytic reduction and oxidation reactions.
关键词： Z-scheme charge transfer,NiO/TiO2 hybrid,Photocatalysis,Surface defects,Self-doping of Ti3+
更新于2025-09-09 09:28:46
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Respective construction of Type-II and direct Z-scheme heterostructure by selectively depositing CdS on {001} and {101} facets of TiO2 nanosheet with CDots modification: A comprehensive comparison
摘要： Directional deposition has always been a focus issue in the construction of specific heterostructure. Herein, for the first time, we have demonstrated that the CdS could be selectively deposited on {001} or {101} facets of TiO2 nanosheet, and two different charge transfer processes were formed. First, the selective deposition of CdS on {001} facets of TiO2 nanosheet ({001}TiO2/CdS) would form the Type-II heterostructure, which seriously weakened the redox ability of {001}TiO2/CdS and directly resulted in the low photocatalytic performance (4-Chlorophenol (4-CP), 61.92% in 40 min) and serious photocorrosion of CdS. In contrary, the selective deposition of CdS on {101} facets of TiO2 nanosheet ({101}TiO2/CdS) could construct direct Z-scheme heterostructure with significantly increased photocatalytic 4-CP degradation efficiency (96.12%), much higher than pristine TiO2 nanosheet (87.21%). The hybrids were further modified by carbon nanodots (CDots) ({101}TiO2/CdS/CDots) to enhance photocatalytic performance (99.84%). The obtained direct Z-scheme {101}TiO2/CdS/CDots showed excellent stability and anti-photocorrosion ability. The synergistic effect between TiO2 nanosheet, CdS and CDots was expounded through characterization analyses, and the photocatalytic reaction mechanism was proposed in detail. Toxicity assessment authenticated good biocompatibility and low cytotoxicity of {101}TiO2/CdS/CDots. Our discovery was expected to drive great advances in the use of TiO2 nanosheet for environmental remediation.
关键词： Toxicity,Selective CdS deposition,Z-scheme heterostructure,TiO2 nanosheet,Anti-photocorrosion
更新于2025-09-09 09:28:46
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Application of a photostable silver-assisted Z-scheme NiTiO3 nanorod/g-C3N4 nanocomposite for efficient hydrogen generation
摘要： The performance and reaction mechanism of a silver (Ag)-assisted one-dimensional NiTiO3 nanorod/CN heterostructure nanocomposite (NTACN) photocatalyst for hydrogen (H2) production were explored with simulated sunlight. The physicochemical properties of the synthesized catalysts were examined using various spectrophotometers. The newly developed NTACN samples displayed an enhanced photocatalytic activity in producing hydrogen. Specifically, the H2 production rate of NTACN-5 (with a NT-to-ACN weight ratio of 5) was 3351 mmol/g-h, which was 1.42 times higher than that of ACN-4 with a Ag-to-CN ratio of 4 (2325 mmol/g-h). The effects of the Ag-to-CN and NiTiO3-to-ACN ratios on the photocatalytic activity of NTACN photocatalysts were determined. The NTACN photocatalysts exhibited a high long-term photostability under simulated sunlight irradiation. The increased photocatalyst performance and photostability were primarily ascribed to an improved charge separation efficiency due to a Z-scheme reaction mechanism as well as the assistance provided by Ag as a charge transfer shuttle and in the surface plasmon resonance effect. A photocatalytic mechanism for hydrogen generation over the NTACN photocatalysts under simulated sunlight irradiation is suggested.
关键词： Photostability,Simulated sunlight,One dimension,Z-Scheme mechanism,Charge transfer shuttle
更新于2025-09-09 09:28:46
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Upconversion Tm3+:CeO2/Palygorskite as direct Z-scheme heterostructure for photocatalytic degradation of bisphenol A
摘要： Novel Tm3+:CeO2/palygorskite (Pal) nanocomposites were prepared by a hydrothermal-deposition method. X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis spectrum（UV-Vis）, photoluminescence spectroscopy（PL）and Mott-Schottky analysis were employed to characterize the products. Results indicated that Pal skeleton possessed abundant adsorption sites and shortened band gap after modified by hydrochloric acid. Tm3+ doping enhanced the utilization of solar light due to its upconversion from visible to ultraviolet light. Meanwhile, the adsorption edge of the Tm3+:CeO2 was extended to visible region with the formation of heterojunctions. The product intimated Tm3+:CeO2/Pal behaved strongest upconversion luminescence when the doping fraction of Tm3+ was optimized to be 0.02, and the photocatalytic degradation of bisphenol A (BPA) reached 86 % when the mass content of Tm3+:CeO2 as compared to Pal was optimized to 10 wt%. The direct Z-scheme system was constructed between Pal and Tm3+:CeO2 leading to the improved charge-separation efficiency and maintenance of high redox potential.
关键词： CeO2,Upconversion,Palygorskite,Photocatalysis,Z-scheme
更新于2025-09-04 15:30:14
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Application of kinetic flux vector splitting scheme for solving viscous quantum hydrodynamical model of semiconductor devices
摘要： In this article, one-dimensional viscous quantum hydrodynamical model of semiconductor devices is numerically investigated. The model treats the propagation of electrons in a semiconductor device as the flow of a charged compressible fluid. It plays an important role in predicting the behavior of electron flow in semiconductor devices. The nonlinear viscous quantum hydrodynamic models contain Euler-type equations for density and current, viscous and quantum correction terms, and a Poisson equation for electrostatic potential. Due to high nonlinearity of model equations, numerical solution techniques are applied to obtain their solutions. The proposed numerical scheme is a splitting scheme based on the kinetic flux-vector splitting (KFVS) method for the hyperbolic step, and a semi-implicit Runge-Kutta method for the relaxation step. The KFVS method is based on the direct splitting of macroscopic flux functions of the system on the cell interfaces. The second order accuracy of the scheme is achieved by using MUSCL-type initial reconstruction and Runge-Kutta time stepping method. Several case studies are considered. For validation, the results of current scheme are compared with those obtained from the splitting scheme based on the NT central scheme. The effects of various parameters such as device length, viscosities, different doping and voltage are analyzed. The accuracy, efficiency and simplicity of the proposed KFVS scheme validates its generic applicability to the given model equations.
关键词： Numerical simulation,Kinetic flux-vector splitting scheme,Semiconductor devices,Viscous quantum hydrodynamic model
更新于2025-09-04 15:30:14