Study of structural, electronic and optical properties of co-doped CeO2 using the density functional theory (DFT) method

The (B, C), (B, H), (B, N), (B, O), (B, P) and (B, S) co-doping effects on structural, electronic and optical properties of CeO2 systems have been studied to determine their potential for photo-catalytic activity using density functional theory and Hubbard U method. Both metallic and nonmetallic co-doping of elements show increase in cell volume and produce local lattice distortion. Due to this co-doping, energy gap between valence and conduction bands becomes narrower than that of pure CeO2, which provides easy way for the transfer of electrons from oxygen 2p orbitals to Ce 4f orbitals assisting in the process for photo-catalysis. Atomic orbitals of similar energy are mixed together except for the atomic s orbital of hydrogen atom. Further, optical absorption peaks for (B, C), (B, H) and ((B, N) co-doped CeO2 systems are found at higher energy range (blue shift) predicting to be better photo-catalytic material. Co-doped CeO2 materials are expected to speed up photoreaction and more electromagnetic waves are allowed to pass through them. Co-doping causes impurity levels to appear in the forbidden energy gap. Extended visible light absorption region has been observed leading to photo-catalytic activity enhancement for the visible light range (similar to 1.5-6.2 eV).