Electronic structure of InAs/GaSb core-shell nanowires

AbstractIn the present work, we have modified the physical and electronic structure of Sb/Ge core/shell nanowires via vacancy creation and doping with foreign atoms with the aim to improve their thermoelectric energy conversion efficiency. Sb/Ge-NWs having a diameter of 1.5 Å show metallicity with 2Go quantum conductance. The stability of the nanowires is assessed through the calculation of their formation energy. The formation of one vacancy at either the Sb- and Ge-site modifies substantially the electronic properties. From the comparison of the thermoelectric properties of the nanowires with and without the vacancy, we have found that the figure of merit for the Sb/Ge NW with one Sb vacancy increases of 0.18 compared to the pristine NW. The NW doping with different transition metals: Fe, Co, Ni and Cu have been found to also enhance the conversion efficiency. Thus, our calculations show that the thermoelectric performance of metal–semiconductor core–shell NWs can be in principle improved as much as 80% by vacancy formation and doping.

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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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