First-principles investigation of the electronic properties of the Bi2O4(101)/BiVO4(010) heterojunction towards more efficient solar water splitting

Abstract

First-principles calculations based on density functional theory were carried out to explore the geometric structure, light absorption, charge separation, over-potential and stability of Bi₂O₄ (101)/BiVO₄ (010) heterojunction. The results show that the formed heterojunction can improve visible light utilization and promote transfer of photo-generated holes from BiVO₄ to Bi₂O₄. Furthermore, the Bi⁵⁺ site in the Bi₂O₄(101) surface is energetically more favorable as the photoanode for the oxygen evolution reaction (OER) than the Bi³⁺ sites in Bi₂O₄(101) and BiVO₄(010). At the same time, it is also found that the Bi⁵⁺ in Bi₂O₄(101) are more stable than the Bi³⁺ due to the lower surface energy and stronger bond energy with neighbors. Therefore, forming the Bi₂O₄/BiVO₄ heterojunction can effectively improve the activity and stability of BiVO₄ for water splitting reactions.