| Autor: |
Shtarev DS; Yu. A. Kosygin Institute of Tectonics and Geophysics FEB RAS, 680000 Khabarovsk, Russia., Kevorkyants R; Saint-Petersburg State University, Laboratory 'Photoactive Nanocomposite Materials', 199034 St Petersburg, Russia., Molokeev MS; Far Eastern State Transport University, 680000 Khabarovsk, Russia.; Kirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, Russia.; Siberian Federal University, 660041 Krasnoyarsk, Russia., Shtareva AV; Yu. A. Kosygin Institute of Tectonics and Geophysics FEB RAS, 680000 Khabarovsk, Russia. |
| Abstrakt: |
We report the synthesis and the crystal and electronic structure as well as the optical and photocatalytic properties of novel photoactive materials of the general formula Bi 26- x Mg x O 40 . Two compounds with compositions of Bi 24.28(3) Mg 1.72(3) O 40 and Bi 24.05(3) Mg 1.95(3) O 40 are synthesized using the pyrolytic method. According to X-ray diffraction analysis, the materials are monocrystalline species. Their electronic bandgaps determined from Tauc plots are 2.41 eV [Bi 24.28(3) Mg 1.72(3) O 40 ] and 2.69 eV [Bi 24.05(3) Mg 1.95(3) O 40 ]. Keeping in mind that optical bandgaps are typically larger than their electronic counterparts, we find that the bismuthate bandgaps match well that of Bi 24 Mg 2 O 40 (2.26 eV) predicted by density functional theory. Apparently, the synthesized bismuthates are indirect bandgap semiconductors just like Bi 24 Mg 2 O 40 . Both materials demonstrate nearly identical luminescence spectra. Their luminescence emission at 620 nm is most efficiently excited by 365 nm light. The materials' photocatalytic properties are evaluated in a visible light-induced photocatalytic phenol degradation reaction. Rather low activity of both compounds is detected. However, Bi 24.05(3) Mg 1.95(3) O 40 is ∼2 times more photocatalytically active than Bi 24.28(3) Mg 1.72(3) O 40 , which is associated with a higher Bi 5+ content in the former. |
