Density functional theory (DFT) investigation on the structure and photocatalysis properties of double-perovskite Gd_1-xCa_xBaCo₂O_5+δ (0 ≤ x ≤ 0.4)

GdBaCo₂O_5+δ (GCBC) has been widely used in various applications because of its unique structural characteristics. However, calcium-doped GCBC materials have not been comprehensively studied in terms of their structure and catalytic properties. Based on the first-principles density functional theory, the structure and electronic density of states were revealed by experiments and simulations. Ca-doping has a great influence on the materials' crystal structure, optical absorption, and catalytic performance. Furthermore, Gd_0.8Ca_0.2BaCo₂O_5+δ show the best efficiency in the photocatalytic degradation of congo red (C₃₂H₂₂N₆Na₂O₆S₂). The presented Ca-doping method affects the overall band structure, electron cloud distribution, and electronic density of states to strengthen the charge-transfer between O-2p and Co-3d orbitals, and Co may be an active site. Our results provide a deep and systematic study on Gd_1-xCa_xBaCo₂O_5+δ based on theoretical calculations and experiments, including analysis of crystal structure, electron distribution, and catalytic performance.