The electronic structure and the photoluminescence property of the photocatalyst BaZn 1/3 Nb 2/3 O 3
- PDF / 163,589 Bytes
- 4 Pages / 585 x 783 pts Page_size
- 43 Downloads / 206 Views
W.F. Zhang Department of Physics, Henan University, Kaifeng 475001, China
X.Y. Liu Ames Laboratory, Iowa State University, Ames, Iowa 50011
J. Yina) and Z.G. Liu National Laboratory of Solid State Microstructure, Nanjing University, Nanjing 210093, China (Received 10 October 2006; accepted 6 February 2007)
The photocatalyst BaZn1/3Nb2/3O3 with ABO3 perovskite structure has been synthesized by using a solid-state reaction process. It was characterized by x-ray diffraction and photoluminescence spectroscopy. The luminescence band centers around 285 nm and shows a large Stokes shift compared with the excitation spectrum, indicating a strong electron–phonon interaction in the photocatalyst BaZn1/3Nb2/3O3. The electronic structure of BaZn1/3Nb2/3O3 was calculated by using the pseudopotential method of the density function theory. It shows that the conduction band should be mainly composed of the Nb 4d states, and the valence band should be mainly composed of the O 2p state. The densities of the O 2p states and the Zn 4s states at the bottom of the conduction band are very low. The Zn 4s states show an expanded structure, which was proposed to be helpful for the migration of the photoexcited carriers, thus favoring the photocatalytic activity of BaZn1/3Nb2/3O3.
I. INTRODUCTION
The attractive prospects of the applications in the conversion of solar energy to chemical energy stored in gaseous hydrogen have led to great efforts to develop new photocatalysts1–3 and to understand the scattering mechanism of the photoexcited carriers in the photocatalysts.4 Some photocatalysts with special electronic structures and crystal structures such as MIn1/2Nb1/2O3 (M ⳱ Ca, Sr, and Ba), MIn2O4 (M ⳱ Ca, Sr), MCo1/3Nb2/3O3, and PbBi2Nb2O9 etc. were reported.5–8 It was proposed that the photocatalysts containing octahedrally coordinated d10 p-block metals are active for water decomposition.6 In addition, the photocatalysts with ns0 (n − 1)d10 electronic structure, such as ZnS and CdS etc.9–11 although they are unstable chemically, also show quite favorable photocatalytic activity under ultraviolet (UV) or visible light irradiation. In previous work, we developed an ABO3 perovskite photocatalyst BaZn1/3Nb2/3O3 with a good chemical stability and good photocatalytic activity
a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2007.0276 J. Mater. Res., Vol. 22, No. 8, Aug 2007
http://journals.cambridge.org
Downloaded: 14 Mar 2015
under UV light irradiation.12 Here we report the photoluminescence (PL) property and electronic structure of this material, which is helpful for us to understand its promising photocatalytic properties. II. EXPERIMENTAL
The photocatalyst BaZn1/3Nb2/3O3 was synthesized by using a solid-state reaction method with the starting materials of high purity including BaCO3 (purity 99.99%), ZnO (purity 99%), and Nb2O5 (purity 99%). The ground and well-mixed powder in a stoichiometric ratio was preheated at 900 °C for 8 h. The reground powder was sintered at 1250 °C for 24 h. The cry
Data Loading...
