Enhancement of Thermoelectric Performance by Reducing Phonon Thermal Conductance in Multiple Core-shell Nanowires

The twist angle can induce phonon interference effect in the intermediately coupled molecular junctions and significantly suppress phonon thermal conductance.

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Thermoelectric Modeling of Si-Si1−xGex Ordered Nanowire Composites

MRS Proceedings ◽

10.1557/proc-0886-f06-02 ◽

2005 ◽

Vol 886 ◽

Author(s):

Ming Y. Tang ◽

Mildred S. Dresselhaus ◽

Ronggui Yang ◽

Gang Chen

Keyword(s):

Thermoelectric Materials ◽

Model Systems ◽

Thermoelectric Performance ◽

Core Shell ◽

Host Matrix ◽

Electronic Density ◽

Quantum Confinement Effects ◽

Interface Scattering ◽

Low Dimensional ◽

Shell Nanowires

ABSTRACTThermoelectrics have always been attractive for power generation and cooling because of power reliability and environmentally friendly issues. However, this concept remains non-competitive due to the limitation in the efficiency of available thermoelectric materials and device designs [1]. In the 1990s, Hicks and Dresselhaus predicted the possibility of a dramatic enhancement in thermoelectric performance based on the special behavior of low dimensional materials [2, 3]. This enhancement is in part due to the increase in quantum confinement effects, the increase in electronic density of states at specified energies, and the increase in the phonon interface scattering for low dimensional structures.Nanowires and core-shell nanowires can be considered to be model systems to illustrate representative behavior in low dimensional thermoelectric materials. It is expected that a system made out of nanowires or core-shell nanowires would have a higher thermoelectric performance than its bulk counterpart due to an increase in the number of interfaces. The interfaces that are introduced must be such that phonons are scattered more strongly than are electrons. Theoretical studies have been carried out to better understand the transport properties of Si-Si1−xGex ordered nanowire composites. The composite is modeled as having Si wires embedded in a Si1−xGex host matrix. Thus, core-shell Si/Si1−xGex nanowires can be considered as a building block of the composite. The effect of the wire diameter and the shell alloy composition on ZT is presented.

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High Thermoelectric Performance of Ge/Si Core−Shell Nanowires: First-Principles Prediction

The Journal of Physical Chemistry C ◽

10.1021/jp101132u ◽

2010 ◽

Vol 114 (19) ◽

pp. 9096-9100 ◽

Cited By ~ 32

Author(s):

Xin Chen ◽

Yanchao Wang ◽

Yanming Ma

Keyword(s):

First Principles ◽

Thermoelectric Performance ◽

Core Shell ◽

Shell Nanowires

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Influence of Core-Shell Architecture Parameters on Thermal Conductivity of Si-Ge Nanowires

MRS Proceedings ◽

10.1557/opl.2015.242 ◽

2015 ◽

Vol 1735 ◽

Author(s):

Sevil Sarikurt ◽

Cem Sevik ◽

Alper Kinaci ◽

Justin B. Haskins ◽

Tahir Cagin

Keyword(s):

Thermal Conductivity ◽

Thermoelectric Performance ◽

Core Shell ◽

Core Size ◽

Dynamic Simulations ◽

Cross Sectional ◽

Shell Nanostructures ◽

Different Temperatures ◽

Shell Nanowires ◽

Equilibrium Molecular Dynamic

ABSTRACTIn this work, we investigate the influence of the core-shell architecture on nanowire (1D) thermal conductivity targeting to evaluate its validity as a strategy to achieve a better thermoelectric performance. To obtain the thermal conductivity values, equilibrium molecular dynamic simulations is applied to Si and Ge systems that are chosen to form core-shell nanostructures. To explore the parameter space, we have calculated thermal conductivity values of the Si-core/Ge-shell and Ge-core/Si-shell nanowires at different temperatures for different cross-sectional sizes and different core contents. Our results indicate that (1) increasing the cross-sectional area of pristine Si and pristine Ge nanowire increases the thermal conductivity (2) increasing the Ge core size in the Si-core/Ge-shell structure results in a decrease in the thermal conductivity values at 300 K (3) thermal conductivity of the Si-core/Ge-shell nanowires demonstrates a minima at specific core size (4) no significant variation in the thermal conductivity observed in nanowires for temperature values larger than 300 K (5) the predicted thermal conductivity around 10 W m−1K−1 for the Si and Ge core-shell architecture is still high to get desired ZT values for thermoelectric applications. On the other hand, significant decrease in thermal conductivity with respect to bulk thermal conductivity of materials and pristine nanowires proves that employing core–shell architectures for other possible thermoelectric material candidates would serve valuable opportunities to achieve a better thermoelectric performance.

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One-Dimensional TiO2@GaON Core-Shell Nanowires with Controlled Shell Thickness from Atomic Layer Deposition for Stable and Efficient Photoelectrochemical Water Splitting

10.26434/chemrxiv.9199796 ◽

2019 ◽

Author(s):

Jiajia Tao ◽

Hong-Ping Ma ◽

Kaiping Yuan ◽

Yang Gu ◽

Jianwei Lian ◽

...

Keyword(s):

Atomic Layer Deposition ◽

Band Gap ◽

Water Splitting ◽

Atomic Layer ◽

Photoelectrochemical Water Splitting ◽

Core Shell ◽

Photoelectrochemical Performance ◽

Highly Efficient ◽

Layer Deposition ◽

Shell Nanowires

<div>As a promising oxygen evolution reaction semiconductor, TiO2 has been extensively investigated for solar photoelectrochemical water splitting. Here, a highly efficient and stable strategy for rationally preparing GaON cocatalysts on TiO2 by atomic layer deposition is demonstrated, which we show significantly enhances the</div><div>photoelectrochemical performance compared to TiO2-based photoanodes. For TiO2@20 nm-GaON core-shell nanowires a photocurrent density up to 1.10 mA cm-2 (1.23 V vs RHE) under AM 1.5 G irradiation (100 mW cm-2) has been achieved, which is 14 times higher than that of TiO2 NWs. Furthermore, the oxygen vacancy formation on GaON as well as the band gap matching with TiO2 not only provides more active sites for water oxidation but also enhances light absorption to promote interfacial charge separation and migration. Density functional theory studies of model systems of GaON-modified TiO2 confirm the band gap reduction, high reducibility and ability to activate water. The highly efficient and stable systems of TiO2@GaON core-shell nanowires provide a deeper understanding and universal strategy for enhancing photoelectrochemical performance of photoanodes now available. </div>

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