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Ternary Ag nanoparticles/natural-magnetic SiO2-nanowires/reduced graphene oxide nanocomposites with highly visible photocatalytic activity for 4-nitrophenol reduction
摘要： Agglomerate and reuse limit the promising application of silver nanoparticles (AgNPs) as catalyst. To eliminate those disadvantages, herein, Fe-containing silica nanowires (SiO2NWs) and reduced graphene oxide (RGO) are used as suitable substrates to prepare AgNPs/SiO2NWs/RGO nanocomposite via self-assembly approach. The nanocomposite mostly assembled with each other via intermolecular hydrogen bond and electrostatic adsorption to form a three-dimensional network structure. The AgNPs/SiO2NWs/RGO nanocomposite exhibit excellent photocatalytic activity for 4-nitrophenol reduction by NaBH4, originating from that the nearly mono-dispersed AgNPs are adhered on the surface of the SiO2NWs and RGO, allowing the effective contact of reactants with catalyst and facilitating the electron transfer between them in the reaction. The obtained nanocomposites exhibit the superior stability and can be easily recovered with their fully catalytic activities due to the hydrophobic and magnetic properties of the nanocomposites. It shows the great prospect for the 4-NP reduction in practice and is promising for wide applications in visible light catalytic reaction.
关键词： SiO2 nanowires,Photo-catalytic activity,Reduced graphene oxide,Silver nanoparticles,4-Nitrophenol reduction
更新于2025-09-23 15:22:29
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Interfacial Charge Transfer in 0D/2D Defect-Rich Heterostructures for Efficient Solar-Driven CO2 Reduction
摘要： Two-dimensional graphitic carbon nitride (g-C3N4) has been widely explored as a promising photocatalyst for solar CO2 conversion. However, rapid charge recombination and low visible-light utilization are severely detrimental to photocatalytic CO2 conversion. Zero-dimensional/two-dimensional (0D/2D) heterostructures are considered the promising materials with size tunability and enhanced charge separation efficiency for photocatalysis. Herein, a 0D/2D heterostructure of oxygen vacancy-rich TiO2 quantum dots confined in g-C3N4 nanosheets (TiO2-x/g-C3N4) was prepared by in-situ pyrolysis of NH2-MIL-125 (Ti) and melamine. Charge dynamics analysis by time-resolved photoluminescence (tr-PL) and femtosecond and nanosecond pump-probed transient absorption (TA) spectra revealed that charges transfer occured from 2D-g-C3N4 to 0D-TiO2 at an ultrafast subpicosecond time scale (<1 ps) through the intimate interface. The overall fast decay of the charge carriers was attributed to interfacial charge transfer, which was accompanied by recombination relaxation mediated by shallow trapped sites. Ultrafast interfacial charge transfer greatly promoted charge separation as well as electrons in shallow trapped sites were easily trapped by CO2. In addition, combing with the synergetic advantage of strong visible light absorption, high CO2 adsorption and large surface area, TiO2-x/g-C3N4 exhibited a superior CO evolution rate of 77.8 μmol g?1 h?1, roughly 5 times that of pristine g-C3N4 (15.1 μmol g?1 h?1). This work provides in-depth insights into optimizing the heterojunction for robust solar CO2 conversion.
关键词： TiO2 quantum dots,solar CO2 reduction,charge transfer,0D/2D heterostructures,oxygen vacancy
更新于2025-09-23 15:22:29
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Surface structural alteration of multi-walled carbon nanotubes decorated by nickel nanoparticles based on laser ablation/chemical reduction methods to enhance hydrogen storage properties
摘要： The catalytic effect of nickel is addressed to decorate the multi-walled carbon nanotubes for the purpose of hydrogen storage. The hydrogen sorption/desorption are investigated using the volumetric technique. Nickel nanoparticles are distributed on the surface of nanotubes using the laser ablation/chemical reduction treatments. The hydrogen uptake is elevated at higher nickel population up to a certain value and then experiences a significant drop for larger nickel content. The laser treatment is accompanied by the induced pores around nanotubes. This gives rise to the creation of the larger pores at higher laser doses leading to decrease the hydrogen trapping. Despite the pore size distribution strongly alters during both synthesis methods, however the abundance of small pore size in laser treatments is relatively higher than the that of the other technique. In comparison, the laser ablation demonstrates a relatively smaller desorption temperature against chemical one, mainly owing to the formation of larger pore size/volume. Generally, the hydrogen trapping efficiently takes place in the laser treated samples against chemical reduction method. The highest value of hydrogen storage ~1% (0.6% weight) is corresponding to 12.3% (13% weight) of nickel loading via the laser ablation (chemical reduction).
关键词： Hydrogen uptake,Nickel nanoparticles,Laser ablation,Chemical reduction,Pore size
更新于2025-09-23 15:22:29
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A Zn(II)/anthracene coordination polymer showing highly efficient photocatalytic Cr(VI) reduction in aqueous solution
摘要： Reaction of Zn(OAc)2·2H2O with the visible light responsive organic ligand 9,10-bis(4′-pyridylethynyl)-anthracene (BPEA) gave rise to a Zn(II)/anthracene coordination polymer [Zn(OAc)2(BPEA)]n. Compound 1 has a one-dimensional (1D) chain structure in which the binuclear {Zn2(OAc)2} cores are linked by the BPEA ligands using the pyridyl N atoms to give to the 1D ladder-like network. The as-prepared compound 1 shows broad-range visible light absorption and good water stability, which are highly demandable for its application in the photocatalysis. The photocatalytic property of 1 were investigated by reduction of Cr(VI) to Cr(III) in aqueous solution under visible light, which reveals its high efficiency and stability in this photocatalytic process.
关键词： Anthracene-based ligand,Coordination polymer,Photocatalysis,Cr(VI) reduction
更新于2025-09-23 15:22:29
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Monometallic Catalytic Models Hosted in Stable Metal-Organic Frameworks for Tunable CO2 Photoreduction
摘要： The photocatalytic reduction of CO2 to energy carriers has emerged as one of the most promising strategy to alleviate the energy crisis and CO2 pollution, for which the development of catalyst was considered as the determining factor for the accomplishment of this conversion process. In this study, three stably and isostructural metal organic frameworks (denoted as MOF-Ni, MOF-Co and MOF-Cu), have been synthesized and used as heterogeneous catalysts applied into photocatalytic CO2 reduction reaction (CO2RR). It is worth noting that the MOF-Ni exhibited a very high selectivity of 97.7% for photoreducing CO2 to CO, which has exceeded most of the reported MOF-based catalysts in the field. Significantly, the MOFs associated with monometallic catalytic centre offer a simply and precisely structural model which allows us to understand the specific effects of different metal ion species on photoreduction of CO2 as well as reactive mechanism more intuitively.
关键词： Isostructural,Metal-Organic Frameworks,Photocatalytic CO2 Reduction,High Selectivity,Monometallic Catalytic Model,Reactive Mechanism
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Intelligent and Advanced System (ICIAS) - Kuala Lumpur, Malaysia (2018.8.13-2018.8.14)] 2018 International Conference on Intelligent and Advanced System (ICIAS) - Deep Features and Data Reduction for Classification of SD-OCT Images: Application to Diabetic Macular Edema
摘要： Diabetic Macular Edema (DME) is defined as the accumulation of extracellular fluids in the macular region of the eye, caused by Diabetic Retinopathy (DR) that will lead to irreversible vision loss if left untreated. This paper presents the use of a pre-trained Convolutional Neural Network (CNN) based model for the classification of Spectral Domain Optical Coherence Tomography (SD-OCT) images of Diabetic Macular Edema (DME) with feature reduction using Principal Component Analysis (PCA) and Bag of Words (BoW). The model is trained using SD-OCT dataset retrieved from the Singapore Eye Research Institute (SERI) and is evaluated using an 8-fold cross validation at the slide level and two patient leave out at the volume level. For the volume level, an accuracy of 96.88% is obtained for data that was preprocessed.
关键词： Diabetic Macular Edema,Dimension reduction,CNNs,SD-OCT
更新于2025-09-23 15:22:29
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Recent Improvements in the Production of Solar Fuels: From CO <sub/>2</sub> Reduction to Water Splitting and Artificial Photosynthesis
摘要： This account deals with recent trends and challenges regarding photo(electro)chemical solar fuels produced by CO2 reduction and water splitting. The CO2 reduction process is limited by product selectivity, catalyst stability, and its complex reaction mechanism. A variety of catalysts—including thermocatalysts, photocatalysts, electrocatalysts, and combinations of photo- and electrocatalysts—have been employed to facilitate selective and durable CO2 reduction. In addition, the roles of the supporting electrolyte, pH, reaction temperature, chemical environment, and catalyst surface chemistry in efficient CO2 reduction have been thoroughly studied in recent years. Effective use of solar light is a significant part of realizing efficient solar-to-hydrogen conversion during the water splitting process, and so the response of photo(electro)systems to visible light is key. To this end, several strategies have been studied in detail, including band engineering of photocatalysts, photocatalytic systems that mimic natural photosynthesis, and the development of photoanodes and their combination with photovoltaic systems. Here, we summarize recent developments surrounding the CO2-reduction and water-splitting reactions and progress towards achieving artificial photosynthesis.
关键词： Artificial photosynthesis,CO2 reduction,Water splitting
更新于2025-09-23 15:22:29
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Abundant manganese complex-anchored BiOI hybrid photocatalyst for visible light-driven CO <sub/>2</sub> reduction
摘要： An abundant manganese complex-anchored BiOI hybrid system for CO2 photocatalytic conversion was constructed. Layered BiOI and tricarbonyl Mn bipyridyl complex with carboxyl acid groups were connected with covalent bonds and used as visible light antenna and CO2 reduction reaction centers, respectively. The covalent connection of this hybrid system benefits the transfer of electrons from the semiconductor to the Mn complex. The anchoring group (carboxyl) is the key to CO2 reduction for the direct coupling of the two units, facilitating the transfer of electrons from BiOI to the manganese complexes. The photocatalytic properties and stability of the tricarbonyl Mn–bipyridyl complex were significantly enhanced with the aid of anchored BiOI. A high turnover number (TON = 74) of HCOO? formation from CO2 could be achieved using this hybrid system under visible light irradiation.
关键词： CO2 reduction,Photocatalysis,BiOI,Mn tricarbonyl bipyridyl complex
更新于2025-09-23 15:22:29
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Receive Beam-Steering and Clutter Reduction for Imaging the Speed-of-Sound Inside the Carotid Artery
摘要： Handheld imaging of the tissue’s speed-of-sound (SoS) is a promising multimodal addition to diagnostic ultrasonography for the examination of tissue composition. Computed ultrasound tomography in echo mode (CUTE) probes the spatial distribution of SoS, conventionally via scanning the tissue under a varying angle of ultrasound transmission, and quantifying—in a spatially resolved way—phase variations of the beamformed echoes. So far, this technique is not applicable to imaging the lumen of vessels, where blood ?ow and tissue clutter inhibit phase tracking of the blood echoes. With the goal to enable the assessment of atherosclerotic plaque composition inside the carotid artery, we propose two modi?cations to CUTE: (a) use receive (Rx) beam-steering as opposed to transmit (Tx) beam-steering to increase acquisition speed and to reduce ?ow-related phase decorrelation, and (b) conduct pairwise subtraction of data obtained from repetitions of the scan sequence, to highlight blood echoes relative to static echo clutter and thus enable the phase tracking of blood echoes. These modi?cations were tested in a phantom study, where the echogenicity of the vessel lumen was chosen to be similar to the one of the background medium, which allows a direct comparison of SoS images obtained with the different techniques. Our results demonstrate that the combination of Rx-steering with the subtraction technique results in an SoS image of the same quality as obtained with conventional Tx-steering. Together with the improved acquisition speed, this makes the proposed technique a key step towards successful imaging of the SoS inside the carotid artery.
关键词： atherosclerosis,clutter reduction,plaque characterisation,multimodal imaging,ultrasound tomography
更新于2025-09-23 15:22:29
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Production of Methanol from Aqueous CO <sub/>2</sub> by Using Co <sub/>3</sub> O <sub/>4</sub> Nanostructures as Photocatalysts
摘要： In this work, we report for the first time the photocatalytic activity of Co3O4 nanostructures for the reduction of aqueous CO2 to methanol (MeOH). This could be considered a simple example of artificial photosynthesis. The photocatalysis experiments were developed under simulated solar light of 100 mW/cm2 and without using any sacrificial agent. To carry out this study, nanostructured mixed valence cobalt oxide (Co3O4) powders, with porous nanoparticle aggregates of different morphologies, have been prepared by two synthesis methods. The characterization of structural (PXRD, XPS, SEM, and TEM) and optical (UV-vis-NIR, Raman, and FT-IR) properties, magnetization curves, and surface area (BET) was accomplished.
关键词： Co3O4,photocatalysis,artificial photosynthesis,CO2 reduction,nanostructures,methanol
更新于2025-09-23 15:22:29