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- 实验方案
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Diphenylisobenzofuran Bound to Nanocrystalline Metal Oxides: Excimer Formation, Singlet Fission, Electron Injection, and Low Energy Sensitization
摘要： We report the photophysical properties of the dicarboxylated diphenylisobenzofuran dye (1) bound to nanocrystalline metal oxide surfaces. With increased surface loading of 1, emission from the films is significantly quenched but with a small amount of excimer emission at maximum surface loadings. Long-lived triplets were observed by ns TA spectroscopy that is consistent with singlet fission occurring on mesoporous ZrO2. The evolution of these triplets however could not be convincingly resolved by our sub-nanosecond TA spectroscopy. Dye-sensitized devices composed of 1 on a TiO2|Al2O3 core-shell structure exhibited an unusual decrease, increase, and then decrease in Jsc with respect to the thickness of Al2O3. In these films the Al2O3 acts as a tunneling barrier to slow electron injection from the singlet excited state such that singlet fission, and electron injection from the triplet state become competitive. Proof-of-principle self-assembled bilayer films that exhibit efficient triplet energy transfer from a low energy absorbing dye to 1 is demonstrated as another step towards a SF-based DSSC that can circumvent the Shockley-Queisser limit.
关键词： low energy sensitization,excimer formation,singlet fission,electron injection,diphenylisobenzofuran,nanocrystalline metal oxides
更新于2025-09-23 15:21:21
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Density Functional Theory Calculations of Oxygen-Vacancy Formation and Subsequent Molecular Adsorption on Oxide Surfaces
摘要： The surface oxygen vacancy formation energy (EOvac) is an important parameter in determining the catalytic activity of metal oxides. Estimating these energies can therefore lead to data-driven design of promising catalyst candidates. In the present study, we determine EOvac for various insulating and semiconducting oxides. Statistical investigations indicate that the band gap, bulk formation energy, and electron affinity are factors that strongly influence EOvac. Electrons enter defect states after O desorption, and these states can be in the valence band, mid-gap, or in the conduction band. Subsequent adsorption of O2, NO, CO, CO2, and H2 molecules on an O-deficient surface is also investigated. These molecules become preferentially adsorbed at the defect sites, and EOvac is identified as the dominant factor that determines the adsorption mode as well as a descriptor that shows good correlation with the adsorption energy.
关键词： catalytic activity,molecular adsorption,oxygen vacancy formation energy,metal oxides,density functional theory
更新于2025-09-23 15:21:21
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Performance analysis of c-Si heterojunction solar cell with passivated transition metal oxides carrier-selective contacts
摘要： Transition metal oxides (TMOs) as passivating carrier-selective contact layers are investigated for silicon heterojunction solar cells. MoOx as hole-selective layer and TiOx as an electron-selective layer are explored in detail to design a high-efficiency silicon heterojunction solar cell without any specified surface passivation layer. The thickness and optical transparency of the MoOx hole-selective layer have been evaluated through optical simulation. The impact of TMOs’ work function and their passivation quality has been examined in detail to extract the maximum conversion efficiency from silicon heterojunction solar cells. To increase the optical absorption in c-Si, the micro–nanopillar structure has also been implemented. It has been found that the barrier height at the TMO/silicon heterocontact plays a significant role in the overall performance improvement of the solar cell. The optimized cell design without doping and separate passivating layer can achieve a power conversion efficiency of ~ 22%. Our findings open the potential pathways and opportunities to obtain simplified heterojunction solar cells at lower temperatures and without impurity doping.
关键词： Surface recombination velocity,Carrier-selective contact layers,Transition metal oxides,c-Si heterojunction solar cells
更新于2025-09-23 15:21:01
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Metal Oxides in Energy Technologies || Metal oxides in energy-saving smart windows
摘要： Some 30%–40% of the energy generated in the world is used currently in lighting, ventilating, heating, cooling, and operations of buildings and other structures [1]. Especially air conditioners account for a large amount of energy consumed. Therefore, if the energy exchange between the interior and exterior of buildings through window-panes could be more efficiently controlled, substantial energy savings would result. For example, a highly effective strategy would be to coat thin films on windows to minimize the effects of solar radiation and black-body radiation. For effective use of energy in such buildings, window glass is needed with a high solar transmittance but a low thermal emittance on cold days to allow visible light to enter and to prevent loss of heat. On the other hand, windows should at the same time be transparent to visible radiation and reflect infrared (IR) radiation on hot days, to keep the inside of the building cool. Generally, window glass with a solar-control coating, or the so-called “smart window,” is designed for intelligent control of the amount of light and heat [mainly in the near-IR (NIR) region] passing through the window, in response to an external stimulus such as light (photochromic), heat (thermochromic), and electricity (electrochromic).
关键词： energy-saving,smart windows,metal oxides,electrochromic,thermochromic
更新于2025-09-23 15:21:01
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Self-Assembled Nanostructured Tin Oxide Thin Films at the Air-Water Interface for Selective H <sub/>2</sub> S Detection
摘要： Simple, inexpensive and scalable strategies for metal oxide thin film growth are critical for potential applications in the field of gas sensing. Here, we report a general method for the synthesis of free-standing oxide thin films via a one-step, surfactant-free hydrothermal reaction wherein the oxide film forms at the air-water interface. Using SnO2 and PdO as model systems, we show that the thin films, thus formed, have lateral dimensions of the order of centimeters and thickness of the order of tens of nanometers. Transmission Electron Microscopy (TEM) has been used to understand the growth mechanism of the films. Based on these studies, we propose that the metal oxide particles formed in the bulk of the solution move to the interface and get trapped to form a continuous, polycrystalline film. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) measurements have been carried out to understand the structure, morphology and thickness of the films. Thickness tunability by varying the precursor concentration has been explored which in turn affects optical and gas sensing properties. Thin SnO2 films (30nm) revealed ultrasensitive response (R) of 25,000% to 6 ppm H2S at 150oC while demonstrating 25 ppb (R = 19.3%) as the experimental lowest limit of detection. The selectivity of these nanostructured films towards H2S stands tall among the other interfering gases, by exhibiting approximately two orders higher response magnitude. Furthermore, these thin films are highly stable at elevated temperatures.
关键词： Air-water interface,Gas sensing,SnO2,Metal oxides,Self-assembly
更新于2025-09-23 15:19:57
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Non-resonant metal-oxide metasurfaces for efficient perovskite solar cells
摘要： The short-circuit current density and energy conversion efficiency of single-junction perovskite and perovskite/perovskite tandem solar cells can be increased by photon management. In this study, optical metasurfaces were investigated as potential light trapping structures oppose to commonly used pyramidal surface textures. Herein, metal oxide-based non-resonant metasurfaces were investigated as potential light-trapping structures in perovskite solar cells. The zinc oxide nanowire-based building blocks of the metasurface can be prepared by a templated electrodeposition through a mask of resist. The phase of the incident light can be controlled by the edge length of the subwavelength large zinc oxide nanowires. An array of zinc oxide nanowires was prepared and characterized in the current study. Three-dimensional (3D) finite-difference time-domain (FDTD) optical simulations were used to compare solar cells covered with non-resonant metasurfaces with commonly used light trapping structures. As compared to the solar cells covered with zinc oxide pyramid surface texture, solar cells with the integrated non-resonant metasurfaces exhibit almost identical quantum efficiencies and short-circuit current densities. Investigations of such metasurfaces will not only improve the photon absorption in perovskite solar cells but also reveal a pathway to make high-efficiency next-generation solar cells. Detailed guidelines for the realization of non-resonant metal oxide metasurfaces will be provided.
关键词： Light-trapping,Solar cell,Perovskite,Tandem,Metal oxides,Non-resonant metasurface
更新于2025-09-23 15:19:57
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A sola??gel synthesis to prepare size and shape-controlled mesoporous nanostructures of binary (IIa??VI) metal oxides
摘要： A base-catalyzed sol–gel approach combined with a solvent-driven self-assembly process at low temperature is augmented to make manganese oxide (Mn3O4), copper oxide (CuO), and magnesium hydroxide (Mg(OH)2) nanostructures with size- and shape-controlled morphologies. Nanostructures of Mn3O4 with either hexagonal, irregular particle, or ribbon shape morphologies with an average diameter ranged from 100 to 200 nm have been prepared in four di?erent solvent types. In all morphologies of Mn3O4, the experimental XRD patterns have indexed the nanocrystal unit cell structure to triclinic. The hexagonal nanoparticles of Mn3O4 exhibit high mesoporocity with a BET surface area of 91.68 m2 g?1 and BJH desorption average pore diameter of ～28 nm. In the preparation of CuO nanostructures, highly nanoporous thin sheets have been produced in water and water/toluene solvent systems. The simulated XRD pattern matches the experimental XRD patterns of CuO nanostructures and indexes the nanocrystal unit cell structure to monoclinic. With the smallest desorption total pore volume of 0.09 cm3 g?1, CuO nanosheets have yielded the lowest BET surface area of 18.31 m2 g?1 and a BHJ desorption average pore diameter of ～16 nm. The sol of magnesium hydroxide nanocrystals produces highly nanoporous hexagonal nanoplates in water and water/toluene solvent systems. The wide angle powder XRD patterns show well-de?ned Bragg's peaks, indexing to a hexagonal unit cell structure. The hexagonal plates show a signi?cantly high BET surface area (72.31 m2 g?1), which is slightly lower than the surface area of Mn3O4 hexagonal nanoparticles. The non-template driven sol–gel synthesis process demonstrated herein provides a facile method to prepare highly mesoporous and nanoporous nanostructures of binary (II–VI) metal oxides and their hydroxide derivatives, enabling potential nanostructure platforms with high activities and selectivities for catalysis applications.
关键词： catalysis applications,size and shape-controlled morphologies,mesoporous nanostructures,binary (II–VI) metal oxides,sol–gel synthesis
更新于2025-09-23 15:19:57
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Boosted Reactivity of Low-Cost Solar Cells over a CuO/Co <sub/>3</sub> O <sub/>4</sub> Interfacial Structure Integrated with Graphene Oxide
摘要： Developing cost-effective and environment-friendly counter electrodes (CEs) with high performance is central for the commercial application of dye-sensitized solar cells (DSSCs). In this work, the porous interfacial CuO/Co3O4@GO (CCO@GO) hybrid was fabricated by encapsulating the self-assembled CuO/Co3O4 nanosphere in graphene oxide (GO) and acted as a CE for the first time. Further measurements verified that the optimized CCO@GO hybrid not only provided a higher specific surface area (86.7 m2?g?1) with more exposed catalytic sites, but also significantly enhanced the power conversion efficiency (PCE = 8.34%) of DSSC, which was higher than that of the Co3O4-based CE (2.66%) and commercial Pt CE (7.85%). The results indicate that the interfacial CuO/Co3O4@GO hybrid synergistically accelerates the diffusion of I3?/I? redox couple and transmission of electrons, thus promoting the reaction kinetics. This work provides a remarkable way for exploring economical high-performance Pt-free CEs for DSSCs, as well as contributes to the further development for other energy-related fields.
关键词： DSSCs,interfacial structure,transition metal oxides,CuO/Co3O4@GO,counter electrode
更新于2025-09-23 15:19:57
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Functionalized metal oxide nanoparticles for efficient dye-sensitized solar cells (DSSCs): A review
摘要： Dye-sensitized solar cells (DSSCs) are a next-generation photovoltaic energy conversion technology due to their low cost, ability to fabrication on various substrates, structural modifications, excellent transparency, photovoltaic output and its potential applications in wearable devices, energy sustainable buildings, solar-powered windows, etc. DSSC working devices consist of components such as conductive oxide substrates, photoanodes with wide bandgap semiconductors, dye molecules (sensitizers), counter electrodes and redox electrolytes, etc. High-efficiency DSSC devices can be fabricated suitable functionalization of semiconducting metal oxides with quantum dots, organic conjugated polymers, etc. In this review, we discuss different photovoltaic technologies, working principles of DSSCs, fabrication process of devices using various novel inorganic nanostructured materials, influencing parameters on the performance of DSC-device such as photoconversion efficiency (PCE), short circuit current (Jsc), open-circuit voltage (Voc) and fill factor (FF).
关键词： Photovoltaics,Quantum dots,Sensitizers,DSSC-device parameters,Dye-sensitized solar cells (DSSCs),Semiconducting metal oxides
更新于2025-09-23 15:19:57
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Hydrogen reduction behavior and microstructural characteristics of WO3 and WO3-NiO powders
摘要： The characterization and understanding of the hydrogen reduction and sintering behavior of powder mixtures prepared from WO3 and WO3-NiO have been investigated. The nano-sized W and W-Ni powders were prepared by ball milling and hydrogen reduction of oxide powders. The reduction behavior is analyzed by temperature-programmed reduction method with different heating rates in Ar-10% H2 atmosphere. X-ray diffractometry analysis revealed that the oxide powders are changed to W and W-Ni powders with an average particle size of about 100 nm by hydrogen reduction at 800oC for 1 h. The hydrogen reduction kinetics was evaluated by the amount of peak shift with heating rates. The activation energies for the reduction of pure WO3 and WO3-NiO, estimated by the slope of the Kissinger plot, were measured as 87.4–117.4 kJ/mol depending on reduction steps. The consolidated W-Ni by spark plasma sintering has relatively dense and large grains with neck growth by enhanced mass transport due to the addition of Ni. These results are help to optimize the powder synthesis process and to understand the hydrogen reduction behavior and Ni addition effect related to microstructure of powders and sintered bodies.
关键词： Hydrogen reduction behavior,Microstructure,Metal oxides,W and W-Ni,Spark plasma sintering
更新于2025-09-23 15:19:57