Improvement of Photocatalytic Activity of Bi2WO6 by Doping Ag and Y: A DFT Study

Abstract

Although much attention has been recently focused on Bi2WO6 and doping materials as highly efficient visible-light photocatalysts, the selection of an appropriate element as dopant and our understanding of the photocatalytic mechanism from the electronic level still need to be further investigated. In the current work, electronic band structures, density of states, optical properties, and effective mass for Bi2WO6, Ag-doped Bi2WO6 and Y-doped Bi2WO6 semiconductors have been studied by density functional theory calculations. We find that, while both the doped systems show little change in the band gap from Bi2WO6, Ag-doped and Y-doped Bi2WO6 produce more dispersive bands compared to the original Bi2WO6, implying that the doped systems can facilitate the spatial separation of photo-induced electron–hole pairs, and thus enhance the photocatalytic performance. In addition, for Ag-doped Bi2WO6, the presence of an Ag impurity energy band just above the valence band is expected to act as electron-trapping sites leading to a reduction of the recombination rate of photogenerated carriers. Our findings could provide an explanation for the experimental observations reported in the literature.