Fe-doped Bi4O5Br2visible light photocatalyst: A first principles investigation

This study employed first principles calculations to investigate Fe-doped Bi 4 O 5 Br 2 as a potential photocatalyst with high efficiency. Based on formation energy calculation, the Fe atoms prefer to replace the Bi atoms with coordination bond of 3, and the optimal concentration for Fe-doping is 6.06[Formula: see text]wt.%. From surface energy calculations, the [Formula: see text] surface has the lowest surface energy, and therefore the easiest cleavage facet is [Formula: see text]. The key factors for the improvement of photocatalytic efficiency after Fe-doped Bi 4 O 5 Br 2 are estimated as follows. First, the band gap decreases from 2.63[Formula: see text]eV in pristine case to 2.40[Formula: see text]eV in 4 Fe-doped Bi 4 O 5 Br 2 case, resulting in the photon absorption edge shift to lower energy range and the absorption coefficient increase. Secondly, the work functions decrease from 5.66 eV (pristine) to 4.92[Formula: see text]eV (4 Fe-doped Bi 4 O 5 Br 2 ), which facilitate the electrons escaping from the surface. Thirdly, the relative mass ratio of photo-induced electrons and holes increases with Fe concentration. Because the Fe 3[Formula: see text] impurity states in the forbidden band gap become wider, the relative ratio increased after Fe-doped Bi 4 O 5 Br 2 . Finally, the Fe doping process introduces more active sites on the surface, which can effectively improve the capacity of target molecules adsorption. Therefore, it is reasonable to believe that Fe-doped Bi 4 O 5 Br 2 can effectively improve the photocatalytic efficiency because the abovementioned key factors have tremendously improved. Our work provides a reasonable reason for choosing Fe as a dopant, which can help our experimental work and provide explanation for photocatalytic efficiency improvement.