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Properties of gallium zinc oxonitrid...

University of Delaware., Department of Chemistry and Biochemistry.

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Properties of gallium zinc oxonitrides and other mixed metal oxonitride solid solution photocatalyst.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Properties of gallium zinc oxonitrides and other mixed metal oxonitride solid solution photocatalyst./
Author:	Schmidt, Heather R.
Description:	93 p.
Notes:	Source: Dissertation Abstracts International, Volume: 75-02(E), Section: B.
Contained By:	Dissertation Abstracts International75-02B(E).
Subject:	Chemistry, Inorganic. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3598749
ISBN:	9781303475689

Properties of gallium zinc oxonitrides and other mixed metal oxonitride solid solution photocatalyst.
Schmidt, Heather R.

Properties of gallium zinc oxonitrides and other mixed metal oxonitride solid solution photocatalyst. - 93 p.

Source: Dissertation Abstracts International, Volume: 75-02(E), Section: B.

Thesis (Ph.D.)--University of Delaware, 2013.

The photocatalytic splitting of water using solar energy is an appealing source of a clean, renewable fuel with a readily affordable feedstock and products with low environmental impact. Solid solutions of GaN and ZnO are a promising class of photocatalysts, capable of splitting water under visible-light irradiation. Band gaps in the mixed metal oxonitrides are lower than either ZnO or GaN, allowing excitation by visible light. The structural and electronic properties of wurtzite Ga1-xZnxN1-xO x (0 ≤ x ≤ 1) have been studied using density-functional theory with the Full Potential Linear Augmented Plane Wave (FP-LAPW) method. A GGA+U approach is used to accurately describe the semi-core 3d states of Ga and Zn. The calculations show that coupling between the N 2p and Zn 3d states leads to the decreased band gap. The band gap is expected to be minimized at a composition with a Zn concentration higher than those available from current synthetic methods. Formation energies have been calculated to understand the thermodynamic limitations on synthesis of high-Zn materials. Zn formation and GaN formation were considered as potential competing reactions that might limit solid solution formation. Novel spinel structures of zinc gallium oxonitrides (ZGONs) have shown promise as a viable solid solution photocatalyst able to incorporate higher Zn concentrations. Electronic properties of this very complex structure, with and without cation rearrangement, have been studied to compare with the band gap lowering that occurs in the wurtzite structures and determine what features of this new structure contribute to the band gap lowering. x i Similar to the wurtzite structures, the interactions between N 2p states and Zn 3d states cause an insertion of new states at the top of the valence band. Other wurtzite materials were studied in a manner similar to the Zn/Ga oxonitrides, including Al1- xZnxN1-xO x and Fe1-xZnxN1-xOx. Al 1-xZnxN1-xOx has potential to be a solid solution able to absorb visible light however the formation energies and band gaps are higher than Ga1-xZnxN1-xO x. However, Fe1-xZnxN1-xOx show more of a metallic type band structure, and is not likely to have the semiconducting properties needed for photocatalysis. In addition to the study of these mixed metal oxonitrides, a new methodology has been formulated to aid in the optimization process in WIEN2k package using JMP as a statistical analysis tool.

ISBN: 9781303475689Subjects--Topical Terms:

517253
Chemistry, Inorganic.

Properties of gallium zinc oxonitrides and other mixed metal oxonitride solid solution photocatalyst.
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245 1 0 $a Properties of gallium zinc oxonitrides and other mixed metal oxonitride solid solution photocatalyst.
300 $a 93 p.
500 $a Source: Dissertation Abstracts International, Volume: 75-02(E), Section: B.
500 $a Adviser: Douglas J. Doren.
502 $a Thesis (Ph.D.)--University of Delaware, 2013.
520 $a The photocatalytic splitting of water using solar energy is an appealing source of a clean, renewable fuel with a readily affordable feedstock and products with low environmental impact. Solid solutions of GaN and ZnO are a promising class of photocatalysts, capable of splitting water under visible-light irradiation. Band gaps in the mixed metal oxonitrides are lower than either ZnO or GaN, allowing excitation by visible light. The structural and electronic properties of wurtzite Ga1-xZnxN1-xO x (0 ≤ x ≤ 1) have been studied using density-functional theory with the Full Potential Linear Augmented Plane Wave (FP-LAPW) method. A GGA+U approach is used to accurately describe the semi-core 3d states of Ga and Zn. The calculations show that coupling between the N 2p and Zn 3d states leads to the decreased band gap. The band gap is expected to be minimized at a composition with a Zn concentration higher than those available from current synthetic methods. Formation energies have been calculated to understand the thermodynamic limitations on synthesis of high-Zn materials. Zn formation and GaN formation were considered as potential competing reactions that might limit solid solution formation. Novel spinel structures of zinc gallium oxonitrides (ZGONs) have shown promise as a viable solid solution photocatalyst able to incorporate higher Zn concentrations. Electronic properties of this very complex structure, with and without cation rearrangement, have been studied to compare with the band gap lowering that occurs in the wurtzite structures and determine what features of this new structure contribute to the band gap lowering. x i Similar to the wurtzite structures, the interactions between N 2p states and Zn 3d states cause an insertion of new states at the top of the valence band. Other wurtzite materials were studied in a manner similar to the Zn/Ga oxonitrides, including Al1- xZnxN1-xO x and Fe1-xZnxN1-xOx. Al 1-xZnxN1-xOx has potential to be a solid solution able to absorb visible light however the formation energies and band gaps are higher than Ga1-xZnxN1-xO x. However, Fe1-xZnxN1-xOx show more of a metallic type band structure, and is not likely to have the semiconducting properties needed for photocatalysis. In addition to the study of these mixed metal oxonitrides, a new methodology has been formulated to aid in the optimization process in WIEN2k package using JMP as a statistical analysis tool.
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710 2 $a University of Delaware. $b Department of Chemistry and Biochemistry. $3 1023449
773 0 $t Dissertation Abstracts International $g 75-02B(E).
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791 $a Ph.D.
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793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3598749