Premium
DFT calculations on the electronic structures of BiOX (X = F, Cl, Br, I) photocatalysts with and without semicore Bi 5 d states
Author(s) -
Huang Wen Lai,
Zhu Qingshan
Publication year - 2008
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.21055
Subject(s) - pseudopotential , valence (chemistry) , band gap , density functional theory , conduction band , direct and indirect band gaps , semimetal , chemistry , hybrid functional , density of states , electronic structure , condensed matter physics , atomic physics , molecular physics , materials science , computational chemistry , physics , quantum mechanics , organic chemistry , electron
The electronic structures of BiOX (X = F, Cl, Br, I) photocatalysts have been calculated with and without Bi 5 d states using the experimental lattice parameters, via the plane‐wave pseudopotential method based on density functional theory (DFT). BiOF exhibits a direct band gap of 3.22 or 3.12 eV corresponding to the adoption of Bi 5 d states or not. The indirect band gaps of BiOCl, BiOBr, and BiOI are 2.80, 2.36, and 1.75 eV, respectively, if calculated with Bi 5 d states, whereas the absence of Bi 5 d states reduces them to 2.59, 2.13, and 1.53 eV successively. The calculated gap characteristics and the falling trend of gap width with the increasing X atomic number agree with the experimental results, despite the common DFT underestimation of gap values. The shapes of valence‐band tops and conduction‐band bottoms are almost independent of the involvement of Bi 5 d states. The indirect characteristic becomes more remarkable, and the conduction‐band bottom flattens in the sequence of BiOCl, BiOBr, and BiOI. Both O 2 p and X np ( n = 2, 3, 4, and 5 for X = F, Cl, Br, and I, respectively) states dominate the valence bands, whereas Bi 6 p states contribute the most to the conduction bands. With the growing X atomic number, the localized X np states shift closer toward the valence‐band tops, and the valence and conduction bandwidths evolve in opposite trends. Atomic and bond populations have also been explored to elucidate the atomic interactions, along with the spatial distribution of orbital density. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009