Double-Hole-Mediated Codoping on KNbO3for Visible Light Photocatalysis.
In this theoretical study, the double-hole-mediated codoping strategy has been adopted to improve the photocatalytic activity of cubic KNbO3as compared with the corresponding individual doping. The strong double-hole-mediated dopant-dopant coupling significantly reduces the effective bandgaps for the anionic-anionic (N-N, P-P, N-P, C-S) codoped systems with removing the appearing acceptor states above the Fermi level. No dopant-O coupling occurs in the cationic-anionic (V-C, Ti-P, Ti-N, Zr-P, Zr-N, Sc-S, Y-S) codoped systems. The V-C and Ti-P codoping could lead to narrowed bandgaps without unfilled localized states appearing above the Fermi level. N, Ti, Zr, Sc, Y monodoping and Ti-N, Zr-P, Zr-N, Sc-S, Y-S codoping introduce unoccupied impurity states between the valence band maximum and conduction band minimum, which makes them unfavorable for photocatalysis as these impurity states may serve as electron-hole recombination centers. For P-P, N-P, and C-S codoped systems, the intermediate states are higher or close to the hydrogen evolution potential, which is thermodynamically unfavorable for production of both oxygen and hydrogen. Producing hydrogen only, the N-N and C-S codoped KNbO3materials will be good choices for Z-scheme photocatalysis. V, S, and V-C codoped KNbO3may be promising visible light photocatalysts for water splitting, as they have suitable effective bandgaps without the introduction of unoccupied impurity states above the Fermi level, and they also own proper band edge positions with respect to the water redox level. The calculated optical absorption curves also indicate that C, V, and S monodoping and N-N, V-C, and Ti-P codoping can effectively enhance the visible light absorption.
School of Physical Science and Technology, 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.
Guangzhao
G
Wang
School of Physical Science and Technology, 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.
Yuhong
Y
Huang
School of Physical Science and Technology, 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.
Anlong
A
Kuang
School of Physical Science and Technology, 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.
Hongkuan
H
Yuan
School of Physical Science and Technology, 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.
Yang
Y
Li
School of Physical Science and Technology, 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.
Hong
H
Chen