Tuning electronic structure for enhanced photocatalytic performance: theoretical and experimental investigation of CuM 1- x M' x O 2 (M, M' = B, Al, Ga, In) solid solutions.

This study introduces robust screening methodology for the efficient design of delafossite CuM 1- x M' x O 2 solid-solution photocatalysts using band-structure engineering. The investigation not only reveals the formation rules for various CuM 1- x M' x O 2 solid solutions but also highlights the dependence on both lattice compatibility and thermodynamic stability. Moreover, the study uncovers the nonlinear relationship between composition and band gaps in these solid solutions, with the bowing coefficient determined by the substitution constituents. By optimizing the constituent elements of the conduction band edge and adjusting solubility, the band structure of CuM 1- x M' x O 2 samples can be fine-tuned to the visible light region. Among the examined photocatalysts, CuAl 0.5 Ga 0.5 O 2 exhibits the highest H 2 evolution rate by striking a balance between visible-light absorption and sufficient reduction potential, showing improvements of 28.8 and 6.9 times those of CuAlO 2 and CuGaO 2 , respectively. Additionally, CuGa 0.9 In 0.1 O 2 demonstrates enhanced electron migration and surpasses CuGaO 2 in H 2 evolution due to a reduction in the effective mass of photogenerated electrons. These findings emphasize the pivotal role of theoretical predictions in synthesizing CuM 1- x M' x O 2 solid solutions and underscore the importance of rational substitution constituents in optimizing light absorption, reduction potentials, and effective mass for efficient hydrogen production.