Unique hierarchical SiO2@ZnIn2S4marigold flower like nanoheterostructure for solar hydrogen production (original) (raw)
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ZnSe/ZnO Nano-Heterostructures for Enhanced Solar Light Hydrogen Generation
ChemistrySelect, 2017
The one dimensional Zinc Selenide/Zinc Oxide (ZnSe/ZnO) nano-heterostructures were prepared using solvo/hydrothermal reaction technique with varying concentration of ZnSe. The prepared nano-heterostructures were characterized with various techniques. X-Ray Diffraction (XRD) indicates the formation of cubic ZnSe and hexagonal phase of ZnO. Field Emission Scanning Electron Microscopy (FESEM) depicts the formation of rod shaped ZnO nanostructures decorated with spherical nanoparticles of ZnSe. Field Emission Transmission Electron Microscopy (FETEM) validates the formation ZnO nanorods of size 30-40 nm along with spherical ZnSe (25-30 nm) nanostructures. The UV-Visible absorption spectra analysis clearly depicts the extended absorbance in the visible region. Photo-luminescence study indicates the sharp band edge emission peak at 390 nm and broad peak at 475 nm. With further increase in ZnSe concentration, the intensity of band edge emission peak decreases due to the vacancy defects. The photocatalytic performance of prepared ZnSe/ZnO nano-heterostructure was evaluated by studying the hydrogen (H 2) generation via water (H 2 O) splitting under UV-Visible light. The ZnSe/ZnO (10:90 weight ratio) shows 491 mmol of H 2 generation after 4 hours irradiation. With increase in amount of ZnSe upto 10 mol%, the H 2 evolution was also enhanced due to narrowing of the band gap and suppression of recombination rate of charge carriers.
Fabrication of Si nanopowder and application to hydrogen generation and photoluminescent material
Journal of Electrical Engineering, 2017
Si nanopowder is fabricated using the simple beads milling method. Fabricated Si nanopowder reacts with water in the neutral pH region between 7 and 9 to generate hydrogen. The hydrogen generation rate greatly increases with pH, while pH does not change after the hydrogen generation reaction. In the case of the reactions of Si nanopowder with strong alkaline solutions (eg pH13.9), 1600 mL hydrogen is generated from 1 g Si nanopowder in a short time (eg 15 min). When Si nanopowder is etched with HF solutions and immersed in ethanol, green photoluminescence (PL) is observed, and it is attributed to band-to-band transition of Si nanopowder. The Si nanopowder without HF etching in hexane shows blue PL. The PL spectra possess peaked structure, and it is attributed to vibronic bands of 9,10-dimethylantracene (DMA) in hexane solutions. The PL intensity is increased by more than 3,000 times by adsorption of DMA on Si nanopowder.
Controllable Synthesis of Flower-Like Zno Nanostructure with Hydrothermal Method (Research Note)
International Journal of Engineering-Transactions B: Applications, 2009
Flower-like ZnO nanostructures were synthesized by decomposing Zn (OH) 2 in 1, 4-butanediol at 105 C for 36 h. Size of flower-like ZnO nanostructure can be controlled by pH of the aqueous solution. In the preparation of flower-like ZnO nanostructure, zinc nitrate was used as a precursor. The morphology and microstructure of flower-like ZnO nanostructure have been characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. The synthesized flower-like ZnO ...
Science advanced materials
A branched nanorod of ZnO composed of multiple branches that projects from a single nanorod backbone can be realized by using a hydrothermal approach in the presence of a nanoseed with a special structure, namely multi-faceted orthorhombic Zn 2 SiO 4 . Orthorhombic Zn 2 SiO 4 was prepared by annealing the ZnO nanoseed of size ca. 15 nm on a Si substrate at a temperature of 900 C in air for one hour. A typical branched nanorod was constructed by a hexagonal-and rectangular-shaped nanorod arm. HRTEM analysis on the branched structure indicated that the branches exhibited a different crystal growth direction [002] and [100], reflecting the presence of a polytypic growth process in the formation of the branched nanorod structure. The branched nanorod of ZnO and its feature-rich faceted property appears promising for solar cell, catalytic and sensing applications.
RESEARCH NOTE CONTROLLABLE SYNTHESIS OF FLOWER-LIKE ZnO NANOSTRUCTURE WITH HYDROTHERMAL METHOD
Abstract Flower-like ZnO nanostructures were synthesized by decomposing Zn (OH) 2 in 1, 4-butanediol at 105 C for 36 h. Size of flower-like ZnO nanostructure can be controlled by pH of the aqueous solution. In the preparation of flower-like ZnO nanostructure, zinc nitrate was used as a precursor. The morphology and microstructure of flower-like ZnO nanostructure have been characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy.
Novel Zn 2 V 2 O 7 hierarchical nanostructures: Optical and hydrogen storage properties
International Journal of Hydrogen Energy, 2015
The hierarchical nanostructures (HNs) have engrossed immense attention due to their superior performance in catalysis, electronic and energy storage/conversion devices. The multicomponent transition metal oxides (TMOs) have been pointed out as more promising materials for advanced technological applications as compared to their counter binary oxides. Due to the advantages of hierarchical nanostructures and TMOs we have synthesized novel Zn 2 V 2 O 7 hierarchical nanostructures using template free route. The photoluminescence of the sample exhibited an emission at 553.65 nm which can be useful for light emission devices. The hydrogen storage of Zn 2 V 2 O 7 HNs were measured at 473 K and 573 K with an absorption of 1.21 wt.% and 1.81 wt.%., respectively. These studies point out a new class of nanomaterials for possible applications for energy storage and green emission optoelectronic devices.
Enhanced Photocatalytic Hydrogen Production Activities of Au-Loaded ZnS Flowers
ACS Applied Materials & Interfaces, 2013
Utilization of noble metal (e.g. Pt, Au) as co-catalyst seems always indispensable for a photocatalytic H2 production catalyst because most semiconductors lack sufficient active sites. Herein, some non-noble metal active states, Ti 3+ /Ov (oxygen vacancies) and surface amorphization structure, are introduced into anatase TiO2 nanoparticles by ball milling them with TiH2 to prepare black TiO2. And then, an organic/inorganic hybrid (BE-black TiO2) containing a conjugated polymer (BE, a modified poly-benzothiadiazole flake) and black TiO2 is fabricated and investigated for photocatalytic H2 production without noble metal co-catalyst. Compare to BE-TiO2 catalyst, the BE-black TiO2 exhibit a ~30% enhancement for H2 production activity under visible light (λ > 420 nm) irradiation. Combining the structural characterizations, comparison of H2 production rate and electron transfer behavior analysis, it is found that these active states play key role in the enhancement of photoactivity through narrowing the band-gap of TiO2, accelerating photoelectrons transfer from BE to TiO2, acting as electron traps and reaction sites for H2 production.
Synthesis of flowerlike Si nanostructures on Si substrates
Japanese Journal of Applied Physics
The flowerlike Si nanostructures rooted on Si(111) substrates were synthesized using MnCl 2 and Si sources by chemical vapor deposition (CVD). These nanostructures consist of thin Si(111) sheets with a thickness of about 100 nm or less. Their structural properties were clarified in detail by transmission electron microscopy (TEM). Their photoluminescence (PL) measurements revealed that the band edge emission of Si clearly appeared, and dislocation-related emissions were hardly observed. PL spectra showed a thermally stimulated emission with an activation energy of 19 meV in the temperature range between 100 and 200 K. These results suggest that exciton and/or carrier trap centers exist inside the flowerlike Si nanostructures. It is expected that the nanostructures can be used for the improvement of energy devices.