title: A hybrid density functional study on the visible light photocatalytic activity of (Mo,Cr)-N codoped KNbO₃.
abstract: To improve the photocatalytic performance of KNbO3 for the decomposition of water into hydrogen and oxygen, the electronic structure of KNbO3 should be modified to have a suitable bandgap with band edge positions straddling the water redox level so as to sufficiently absorb visible light. Hybrid density functional theory has been used to calculate the electronic structures of pure, N-, Mo-, and Cr-monodoped, and Mo-N and Cr-N codoped KNbO3. In particular, the influence of the relative positions of Mo-N or Cr-N codopants on the electronic structure of KNbO3 is discussed in detail to account for the possible difference in the photocatalytic activity of the codoped samples prepared by different experimental techniques. The defect formation energy calculations indicate that a N-doped system is difficult to form under any conditions and the codoped systems are energetically favorable under Nb-poor and O-rich conditions. It is interesting to find that the effective bandgap and stability for codoped systems decrease with the increase of the dopant concentration and/or the distance between dopants. Furthermore, the suitable bandgap and band edge position with respect to the water redox level make the Mo-N codoped systems good candidates for visible light photocatalytic decomposition of water to generate hydrogen.
authors.affiliation: School of Physical Science and Technology, Southwest University, Chongqing 400715, People's Republic of China. chenh@swu.edu.cn.
authors.forename: Guangzhao
authors.initials: G
authors.lastname: Wang
authors.affiliation: School of Physical Science and Technology, Southwest University, Chongqing 400715, People's Republic of China. chenh@swu.edu.cn and Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, People's Republic of China.
authors.forename: Hong
authors.initials: H
authors.lastname: Chen
authors.affiliation: School of Physical Science and Technology, Southwest University, Chongqing 400715, People's Republic of China. chenh@swu.edu.cn.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: School of Physical Science and Technology, Southwest University, Chongqing 400715, People's Republic of China. chenh@swu.edu.cn.
authors.forename: Anlong
authors.initials: A
authors.lastname: Kuang
authors.affiliation: School of Physical Science and Technology, Southwest University, Chongqing 400715, People's Republic of China. chenh@swu.edu.cn.
authors.forename: Hongkuan
authors.initials: H
authors.lastname: Yuan
authors.affiliation: School of Physical Science and Technology, Southwest University, Chongqing 400715, People's Republic of China. chenh@swu.edu.cn.
authors.forename: Gang
authors.initials: G
authors.lastname: Wu