scholarly journals Unravelling the origin of the giant Zn deficiency in wurtzite type ZnO nanoparticles

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Adèle Renaud ◽  
Laurent Cario ◽  
Xavier Rocquefelte ◽  
Philippe Deniard ◽  
Eric Gautron ◽  
...  
Keyword(s):  
Zno Nanoparticles ◽  
Charge Carriers ◽  
Zn Deficiency ◽  
Core Shell ◽  
Bulk Materials ◽  
Nitrogen Doped ◽  
The Core ◽  
Zinc Peroxide ◽  
P Type

Abstract Owing to its high technological importance for optoelectronics, zinc oxide received much attention. In particular, the role of defects on its physical properties has been extensively studied as well as their thermodynamical stability. In particular, a large concentration of Zn vacancies in ZnO bulk materials is so far considered highly unstable. Here we report that the thermal decomposition of zinc peroxide produces wurtzite-type ZnO nanoparticles with an extraordinary large amount of zinc vacancies (>15%). These Zn vacancies segregate at the surface of the nanoparticles, as confirmed by ab initio calculations, to form a pseudo core-shell structure made of a dense ZnO sphere coated by a Zn free oxo-hydroxide mono layer. In others terms, oxygen terminated surfaces are privileged over zinc-terminated surfaces for passivation reasons what accounts for the Zn off-stoichiometry observed in ultra-fine powdered samples. Such Zn-deficient Zn1-xO nanoparticles exhibit an unprecedented photoluminescence signature suggesting that the core-shell-like edifice drastically influences the electronic structure of ZnO. This nanostructuration could be at the origin of the recent stabilisation of p-type charge carriers in nitrogen-doped ZnO nanoparticles.

Review of the Synthetic Chemistry Involved in the Production of Core/Shell Semiconductor Nanocrystals

2007 ◽  
Vol 60 (7) ◽  
pp. 457 ◽  
Author(s):  
Joel van Embden ◽  
Jacek Jasieniak ◽  
Daniel E. Gómez ◽  
Paul Mulvaney ◽  
Michael Giersig
Keyword(s):  
Semiconductor Nanocrystals ◽  
Critical Role ◽  
Charge Carriers ◽  
Core Shell ◽  
Synthetic Chemistry ◽  
Shell Material ◽  
Growth Processes ◽  
Passivating Layer ◽  
Spectral Shifts

Passivation of CdSe semiconductor nanocrystals can be achieved by overcoating the particles with a homogeneous shell of a second semiconductor. Shell layers are grown in monolayer steps to ensure homogeneous growth of the shell. The relative band edges of the two materials determine the photoreactiveity of the resultant core-shell nanocrystals. The critical role of ligands in minimizing nucleation of the shell material during the growth of the passivating layer is emphasized. The delocalization of charge carriers into the shell layers can be followed spectroscopically during the growth processes. The relative spectral shifts are directly correlated to the relative energies of the band edges.

scholarly journals Asymptotic analysis for the electric field concentration with geometry of the core-shell structure

2021 ◽  
Vol 0 (0) ◽  
pp. 0
Author(s):  
Zhiwen Zhao
Keyword(s):  
Electric Field ◽  
Blow Up ◽  
Core Shell ◽  
Singular Behavior ◽  
Practical Application ◽  
Function Type ◽  
The Core ◽  
The Matrix ◽  
Perfect Conductivity

<p style='text-indent:20px;'>In the perfect conductivity problem arising from composites, the electric field may become arbitrarily large as <inline-formula><tex-math id="M1">\begin{document}$ \varepsilon $\end{document}</tex-math></inline-formula>, the distance between the inclusions and the matrix boundary, tends to zero. In this paper, by making clear the singular role of the blow-up factor <inline-formula><tex-math id="M2">\begin{document}$ Q[\varphi] $\end{document}</tex-math></inline-formula> introduced in [<xref ref-type="bibr" rid="b27">27</xref>] for some special boundary data of even function type with <inline-formula><tex-math id="M3">\begin{document}$ k $\end{document}</tex-math></inline-formula>-order growth, we prove the optimality of the blow-up rate in the presence of <inline-formula><tex-math id="M4">\begin{document}$ m $\end{document}</tex-math></inline-formula>-convex inclusions close to touching the matrix boundary in all dimensions. Finally, we give closer analysis in terms of the singular behavior of the concentrated field for eccentric and concentric core-shell geometries with circular and spherical boundaries from the practical application angle.</p>

The role of diffusion behavior on the formation and evolution of the core‐shell structure in BaTiO 3 ‐based ceramics

2019 ◽  
Vol 103 (1) ◽  
pp. 304-314 ◽  
Author(s):  
Cheng Chen ◽  
Hua Hao ◽  
Jingjing Cui ◽  
Cong Yu ◽  
Yingfei Tang ◽  
...  
Keyword(s):  
Shell Structure ◽  
Core Shell ◽  
Diffusion Behavior ◽  
The Core ◽  
Formation And Evolution ◽  
Core Shell Structure

scholarly journals Unravelling the interfacial interaction in mesoporous SiO2@nickel phyllosilicate/TiO2 core–shell nanostructures for photocatalytic activity

2020 ◽  
Vol 11 ◽  
pp. 1834-1846
Author(s):  
Bridget K Mutuma ◽  
Xiluva Mathebula ◽  
Isaac Nongwe ◽  
Bonakele P Mtolo ◽  
Boitumelo J Matsoso ◽  
...  
Keyword(s):  
Methyl Violet ◽  
Optoelectronic Properties ◽  
Shell Morphology ◽  
Bandgap Energy ◽  
Core Shell ◽  
The Core ◽  
Shell Nanostructures ◽  
Carrier Separation ◽  
First Time

Core–shell based nanostructures are attractive candidates for photocatalysis owing to their tunable physicochemical properties, their interfacial contact effects, and their efficacy in charge-carrier separation. This study reports, for the first time, on the synthesis of mesoporous silica@nickel phyllosilicate/titania (mSiO2@NiPS/TiO2) core–shell nanostructures. The TEM results showed that the mSiO2@NiPS composite has a core–shell nanostructure with a unique flake-like shell morphology. XPS analysis revealed the successful formation of 1:1 nickel phyllosilicate on the SiO2 surface. The addition of TiO2 to the mSiO2@NiPS yielded the mSiO2@NiPS/TiO2 composite. The bandgap energy of mSiO2@NiPS and of mSiO2@NiPS/TiO2 were estimated to be 2.05 and 2.68 eV, respectively, indicating the role of titania in tuning the optoelectronic properties of the SiO2@nickel phyllosilicate. As a proof of concept, the core–shell nanostructures were used as photocatalysts for the degradation of methyl violet dye and the degradation efficiencies were found to be 72% and 99% for the mSiO2@NiPS and the mSiO2@NiPS/TiO2 nanostructures, respectively. Furthermore, a recyclability test revealed good stability and recyclability of the mSiO2@NiPS/TiO2 photocatalyst with a degradation efficacy of 93% after three cycles. The porous flake-like morphology of the nickel phyllosilicate acted as a suitable support for the TiO2 nanoparticles. Further, a coating of TiO2 on the mSiO2@NiPS surface greatly affected the surface features and optoelectronic properties of the core–shell nanostructure and yielded superior photocatalytic properties.

P-Type Nitrogen-Doped ZnO Nanoparticles Stable under Ambient Conditions

2011 ◽  
Vol 134 (1) ◽  
pp. 464-470 ◽  
Author(s):  
Benoit Chavillon ◽  
Laurent Cario ◽  
Adèle Renaud ◽  
Franck Tessier ◽  
François Cheviré ◽  
...  
Keyword(s):  
Zno Nanoparticles ◽  
Ambient Conditions ◽  
Nitrogen Doped ◽  
Doped Zno ◽  
P Type

Nanoparticle@MoS2 Core–Shell Architecture: Role of the Core Material

2018 ◽  
Vol 30 (14) ◽  
pp. 4675-4682 ◽  
Author(s):  
Jennifer G. DiStefano ◽  
Yuan Li ◽  
Hee Joon Jung ◽  
Shiqiang Hao ◽  
Akshay A. Murthy ◽  
...  
Keyword(s):  
Core Material ◽  
Core Shell ◽  
The Core

scholarly journals Role of vacancies to p-type semiconducting properties of SiGe nanowires

2014 ◽  
Vol 2 (32) ◽  
pp. 6536-6546 ◽  
Author(s):  
Rulong Zhou ◽  
Bingyan Qu ◽  
Bo Zhang ◽  
Pengfei Li ◽  
Xiao Cheng Zeng
Keyword(s):  
Core Shell ◽  
First Principle ◽  
First Principle Calculations ◽  
Semiconducting Properties ◽  
P Type

On basis of the first-principle calculations, vacancies are proven to play important roles in p-type semiconducting properties of Si1−xGex nanowires (NW) and Ge/Si core/shell NW.

Effect of graphene and Au@SiO2 core–shell nano-composite on photoelectrochemical performance of dye-sensitized solar cells based on N-doped titania nanotubes

RSC Advances ◽  
2015 ◽  
Vol 5 (103) ◽  
pp. 84423-84431 ◽  
Author(s):  
P. S. Chandrasekhar ◽  
Vamsi K. Komarala
Keyword(s):  
Solar Cells ◽  
Dye Sensitized Solar Cells ◽  
Core Shell ◽  
Photoelectrochemical Performance ◽  
Nano Composite ◽  
Nitrogen Doped ◽  
Dye Sensitized ◽  
Doped Titania ◽  
Sensitized Solar Cells

We have investigated the role of graphene and Au@SiO2 core–shell nano-composite (NC), on the performance of dye-sensitized solar cells (DSSC) based on nitrogen doped TiO2 nanotubes (N-TNTs) as photoanodes.

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