Tailoring the Band Gap in Codoped GaN Nanosheet From First Principle Calculations

Abstract

To develop an efficient photocatalyst with intense visible light absorption and high charge mobility is important but still remains a problem. In this work, we have explored the electronic properties of C-monodoped, C-Ge, and C-Sn codoped GaN nanosheets by the hybrid density functional theory in order to find the excellent photocatalytic materials. Results indicate the monodoping of C introduces unoccupied impurity states inside the band gap that serve on recombination centers. Thus, the C monodoping is not suitable to ameliorate visible light absorption. Moreover, the C-Ge and C-Sn codoping not only successfully reduce the band gap of nanosheet GaN but also avoid the unoccupied impurity states. The charge-compensated C-Ge and C-Sn codoped GaN nanosheets are energetically favorable for hydrogen evolution but not insufficient to produce oxygen, indicating that they could serve as Z-scheme photocatalysts. In particular, the minimum defect formation energy of C-Ge is negative and lowest. The C-Ge codoped GaN system has dynamic stability. So, the C-Ge codoped nanosheet GaN is one of the most prospective candidates for the decomposition of hydrogen from water.