Electronic structures and effective masses of photogenerated carriers of CaZrTi2O7 photocatalyst: First-principles calculations

The band structures, density of states and effective masses of photogenerated carriers for CaZrTi2O7 photocatalyst were performed using first principles method with the virtual crystal approximation. The results indicated that CaZrTi2O7 has an indirect band gap of about 3.25 eV. The upper valence bands of CaZrTi2O7 are formed by O 2p states mixed with Ti 3d states, Zr 4d, 4p and 5s states, while the conduction bands are dominated by Ti 3d states, Zr 4d states and O 2p states. The calculated valence bands maximum (VBM) potential is located at 2.60 V (vs. normal hydrogen electrode (NHE)), while the conduction bands minimum (CBM) potential at −0.65 V. Therefore, CaZrTi2O7 has the ability to split water to hydrogen and oxygen under UV light irradiation. The calculated minimum effective mass of electron in CBM is about 1.35 m0, and the minimum effective mass of hole in VBM is about 1.23 m0. The lighter effective masses facilitate the migration of photogenerated carriers and improve photocatalytic performance.