Effects of Oxidation State on Charge Carrier Lifetimes in B,N Codoped Graphene Oxide Quantum Dots

Abstract

Graphene oxide is an outstanding photocatalyst used in water splitting reaction. However, the oxidation–reduction state causes unstable photocatalytic efficiencies. Electronic structure calculations combined with nonadiabatic molecular dynamics (NAMD) are considered as an effective tool to decipher the catalytic nature in such materials, especially regarding their intrinsic electronic properties. In this work, we performed ab initio NAMD to investigate the phonon-mediated charge relaxation and recombination dynamics in oxidized, partially oxidized, and reduced graphene oxide quantum dots (GOQDs). The relaxation dynamics, such as symmetry and relaxation time, depend on the excitation levels and oxidation states. The partially oxidized and reduced GOQDs exhibit asymmetric relaxations at higher excitation levels, in which the partially oxidized GOQDs exhibit a faster electron decay, whereas the reduced GOQDs exhibit a faster hole decay. At lower excitation levels, the electron decay is faster in oxidized and...