1,721,600 research outputs found
Metal Oxide Semiconductors for Dye- and Quantum-Dot-Sensitized Solar Cells
No full textThis Review provides a brief summary of the most recent research developments in the synthesis and application of nanostructured metal oxide semiconductors for dye sensitized and quantum dot sensitized solar cells. In these devices, the wide bandgap semiconducting oxide acts as the photoanode, which provides the scaffold for light harvesters (either dye molecules
or quantum dots) and electron collection. For this reason,
proper tailoring of the optical and electronic properties of the photoanode can significantly boost the functionalities of the operating device. Optimization of the functional properties relies with modulation of the shape and structure of the photoanode, as well as on application of different materials (TiO2, ZnO, SnO2) and/or composite systems, which allow fine tuning of electronic band structure. This aspect is critical because it determines exciton and charge dynamics in the photoelectrochemical system and is strictly connected to the photoconversion efficiency of the solar cell. The different strategies for increasing light harvesting and charge collection, inhibiting charge losses due to recombination phenomena, are reviewed thoroughly, highlighting the benefits
of proper photoanode preparation, and its crucial role in the development of high efficiency dye sensitized and quantum dot sensitized solar cells
Role of cobalt precursors in the synthesis of hierarchical nanostructures toward the development of cobalt???based functional electrocatalysts for bifunctional water splitting in alkaline and acidic media
No full textThe precursors have significant influence on the catalytic activity of nonprecious electrocatalysts for effective water splitting. Herein, we report active electrocatalysts based on cobalt oxide (Co3O4) hierarchical nanostructures derived from four different precursors of cobalt (acetate, nitrate, chloride, and sulfate salts) using the low-temperature aqueous chemical growth method. It has been found that the effect of precursor on the morphology of nanostructured material depends on the synthetic method. The Co3O4 nanostructures exhibited cubic phase derived from these four precursors. The Co3O4 nanostructures obtained from chloride precursor have demonstrated improved oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) compared to other precursors due relatively higher content of Co3O4 nanostructures at the surface of material. An overpotential of 400 mV versus reversible hydrogen electrode (RHE) at 10 mA cm(-2) was observed for HER. The Co3O4 nanostructures derived from the chloride precursor have shown favorable reaction kinetics via 34 mV dec(-1) value of the Tafel slope for HER reaction. The Co3O4 nanostructures derived from chloride precursor have also shown an excellent HER durability for 15 hr in alkaline media. Furthermore, the OER functional characterization was carried out onto Co3O4 nanostructures derived from chloride precursor exhibited 220 mV overpotential at 10 mA cm(-2) and Tafel slope of 56 mV dec(-1). Importantly, the reason behind the favorable catalytic activity of Co3O4 nanostructures derived from chloride precursor was linked to one order of magnitude smaller charge transfer resistance and higher amount of Co3O4 content at the surface of nanostructures than the Co3O4 nanostructures derived from other precursors. The performance of Co3O4 nanostructures derived from chloride precursor via the wet chemical method suggests that cobalt chloride precursor could be of great interest for the development of efficient, stable, nonprecious, and environmentally friendly electrocatalysts for the chemical energy conversion and storage devices
Solar Cells : Metal Oxide Semiconductors for Dye- and Quantum-Dot-Sensitized Solar Cells
No full textMetal oxide semiconductors are an appealing class of material, extensively used as photoanodes in excitonic solar cells such as dye- and quantum dot-sensitized solar cells. On page 1744, I. Concina and A. Vomiero describe how proper tailoring of the shape, composition, and crystalline structure of these materials can significantly boost the performances of these solar energy converting devices by ameliorating the processes of exciton separation, charge transport, and collection, while reducing charge losses due to recombination and back reactions.</p
Enhanced Mechanical, Thermal and Electrical Properties of High-Entropy HfMoNbTaTiVWZr Thin Film Metallic Glass and its Nitrides
No full textThe inception of high-entropy alloy promises to push the boundaries for new alloy design with unprecedented properties. This work reports entropy stabilisation of an octonary refractory, HfMoNbTaTiVWZr, high-entropy thin film metallic glass, and derived nitride films. The thin film metallic glass exhibited exceptional ductility of approximate to 60% strain without fracture and compression strength of 3 GPa in micro-compression, due to the presence of high density and strength of bonds. The thin film metallic glass shows thermal stability up to 750 degrees C and resistance to Ar-ion irradiation. Nitriding during film deposition of HfMoNbTaTiVWZr thin film of strong nitride forming refractory elements results in deposition of nanocrystalline nitride films with compressive strength, hardness, and thermal stability of up to 10 GPa, 18.7 GPa, and 950 degrees C, respectively. The high amount of lattice distortion in the nitride films leads to its insulating behaviour with electrical conductivity as low as 200 S cm(-1) in the as-deposited film. The design and exceptional properties of the thin film metallic glass and derived nitride films may open up new avenues of development of bulk metallic glasses and the application of refractory-based high entropy thin films in structural and functional applications
Electrochemical Water Splitting: Semiconducting Metal Oxide Nanostructures for Water Splitting and Photovoltaics (Adv. Energy Mater. 23/2017)
No full textSemiconducting metal oxide nanostructures represent an appealing class of materials to be applied as efficient electrodes in electrochemical and photoelectrochemical water splitting and in photovoltaics. In article number 1700706, Isabella Concina, Zafar Hussain Ibupoto, and Alberto Vomiero review the latest achievements in the field, illustrating how the structural and functional properties of metal oxides and metal oxide composites can be optimized for targeted applications.</p
The Renaissance of Luminescent Solar Concentrators: The Role of Inorganic Nanomaterials
No full textWhile luminescent solar concentrators (LSCs) have a simple architecture—a transparent matrix embedding a luminescent fluorophore coupled with solar cells at the lateral side of the LSC slab—multiple paths for possible light losses exist. These are inherently interconnected, and in the past, limited the interest in this device, due to the gap between the theoretical possibilities and experimental achievements. This gap was a result, primarily, of the optical features of the luminescent dyes, since conventional organic luminophores are affected by limited performance in LSC devices. The rise of a wide portfolio of optically active inorganic nanomaterials in the last decade provides an alternative to organic dyes and has lead to a renaissance in the role of LSCs among the unconventional solar energy conversion devices. This paper reviews the latest results in the development of LSCs based on different classes of nanomaterials, focusing on the specific features and critically analyzing the pros and cons of the proposed structures. Particular attention is devoted to the role of the luminescence properties, e.g., the Stokes shift and the photoluminescence quantum yield, with respect to the performance of the LSC device. Future challenges to the successful employment of these devices for building integrated photovoltaics are also discussed
Confined Catalysis: Progress and Prospects in Energy Conversion
No full textSpace confined catalysis has emerged as viable strategy for achieving potent and efficient catalysts in various important reactions. It offers a means of creating unique nanoscale chemical environments partitioned from the surrounding bulk space. This gives rise to the phenomena of nanoconfinement, where the energetics and kinetics of catalytic reactions can be modulated upon confining the catalysts in a particular site. Various scaffolds have been reported so far for confinement. Among these, void spaces under the cover of 2D materials, van der Waals (vdW) gaps of layered 2D materials, nanotubes, and porous surfaces have recently won copious attention. In this review, the concept of space confinement with respect to its effect on the electronic and structural properties of a catalyst is discussed. Emphasis is devoted to the catalysis of water splitting and CO2 reduction reactions. The progress in the design and applications of space confined catalysts is then traced. Finally, a discussion of emerging issues yet to be explored for this strategy to achieve a high efficiency, and future directions with the potential to become a new hotspots are presented
High-Efficiency Deflection of High-Energy Protons through Axial Channeling in a Bent Crystal
No full textThe Renaissance of Luminescent Solar Concentrators: The Role of Inorganic Nanomaterials
No full textWhile luminescent solar concentrators (LSCs) have a simple architecture—a transparent matrix embedding a luminescent fluorophore coupled with solar cells at the lateral side of the LSC slab—multiple paths for possible light losses exist. These are inherently interconnected, and in the past, limited the interest in this device, due to the gap between the theoretical possibilities and experimental achievements. This gap was a result, primarily, of the optical features of the luminescent dyes, since conventional organic luminophores are affected by limited performance in LSC devices. The rise of a wide portfolio of optically active inorganic nanomaterials in the last decade provides an alternative to organic dyes and has lead to a renaissance in the role of LSCs among the unconventional solar energy conversion devices. This paper reviews the latest results in the development of LSCs based on different classes of nanomaterials, focusing on the specific features and critically analyzing the pros and cons of the proposed structures. Particular attention is devoted to the role of the luminescence properties, e.g., the Stokes shift and the photoluminescence quantum yield, with respect to the performance of the LSC device. Future challenges to the successful employment of these devices for building integrated photovoltaics are also discussed
Semiconducting metal oxide nanostructures for water splitting and photovoltaics
No full textMetal oxide (MOx) semiconducting nanostructures hold the potential for playing a critical role in the development of a new platform for renewable energies, including energy conversion and storage through photovoltaic effect, solar fuels, and water splitting. Earth-abundant MOx nanostructures can be prepared through simple and scalable routes and integrated in operating devices, which enable exploitation of their outstanding optical, electronic, and catalytic properties. In this review, the latest research results in this field are illustrated, highlighting the versatility of MOx nanostructures in meeting the stringent requirements to boost the efficiency of different systems. The functional properties inherently correlate to the morphology and the crystalline habit of MOx, which in most of the cases are organized in complex heterostructures. Tailoring the assembly of heterojunctions and their electronic band structure, the catalytic surface properties and the charge transport through complex networks represent the main challenge for the transition of MOx from the research to the real-life in the field of energy conversion and storage
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