N-doped CsTaWO6 as a new photocatalyst for hydrogen production from water splitting under solar irradiation

Mukherji, Aniruddh, Marschall, Roland, Tanksale, Akshat, Sun, Chenghua, Smith, Sean C., Lu, Gao Qing and Wang, Lianzhou (2011) N-doped CsTaWO6 as a new photocatalyst for hydrogen production from water splitting under solar irradiation. Advanced Functional Materials, 21 1: 126-132. doi:10.1002/adfm.201000591


Author Mukherji, Aniruddh
Marschall, Roland
Tanksale, Akshat
Sun, Chenghua
Smith, Sean C.
Lu, Gao Qing
Wang, Lianzhou
Title N-doped CsTaWO6 as a new photocatalyst for hydrogen production from water splitting under solar irradiation
Journal name Advanced Functional Materials   Check publisher's open access policy
ISSN 1616-301X
Publication date 2011-01-07
Year available 2010
Sub-type Article (original research)
DOI 10.1002/adfm.201000591
Volume 21
Issue 1
Start page 126
End page 132
Total pages 7
Place of publication Germany
Publisher Wiley - VCH Verlag GmbH & Co. KGaA
Collection year 2011
Language eng
Formatted abstract
Photocatalysts for efficient solar hydrogen production are highly sought after. Here a new type of nitrogen-doped tantalum tungstenate (CsTaWO 6) material, which demonstrates excellent visible light absorption and improved photocatalytic activity, is demonstrated. X-ray diffraction (XRD) patterns reveal that the defect pyrochlore-type structure of CsTaWO6 remained intact upon nitrogen doping. UV-vis spectra indicate that nitrogen doping in the compound results in a red-shift of the absorption edge from 358 nm to 580 nm, thus offering significantly increased visible light absorption. X-ray photoelectron spectroscopy (XPS) further indicates that [Ta/W]-N bonds were formed by inducing nitrogen to replace a small amount of oxygen in the material, resulting in a compound of CsTaWO6-xNx. The explanation of the experimental results is supported by density functional theory calculations. The density of states (DOS) and the projected DOS after substitutional doping of nitrogen in CsTaWO6 indicated that N-doping reduces the bandgap significantly from 3.8 to 2.3 eV due to N 2p and O 2p orbital mixing. The role of the new N 2p states is also investigated by studying the production of the ·OH radicals in the visible light region (>420 nm). In CsTaWO6-xNx, the N 2p orbitals are the main contributors to the top of the valence band, causing bandgap narrowing while the bottom of conduction band, due to Ta 4d orbitals, remains almost unchanged. Compared with its undoped counterpart, nitrogen-doped CsTaWO6-xN x exhibits a nearly 100% increase in solar hydrogen production efficiency. A significant increase in solar hydrogen production of the wide bandgap semiconductor photocatalyst CsTaWO6 is achieved. Photocatalytic measurements, coupled with detailed spectroscopic studies, indicate that the increase is due to a narrowing of the overall bandgap as a result of uniform nitrogen doping. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Keyword Visible-light irradiation
Tantalum oxide
Oxynitride
Evolution
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2011 Collection
Australian Institute for Bioengineering and Nanotechnology Publications
 
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Created: Mon, 07 Mar 2011, 11:19:39 EST by Mr Akshat Tanksale on behalf of Aust Institute for Bioengineering & Nanotechnology