Band-Edge Electronic Structure on Photo(electro)catalytic Performance of ABO2 (A = Cu, Ag; B = Al, Ga, In): Elucidating the Role of Valence Electron States

A profound understanding of the band-edge electronic structure is crucial for advancing the development of highly efficient photocatalytic materials and unraveling the underlying mechanisms. This study employs a unified and consistent assessment protocol, offering a systematic exploration of the inherent connections between the band-edge electronic structure and the photo­(electro)­catalytic performance of a series of delafossite ABO2 compounds (A = Cu, Ag; B = Al, Ga, In). These compounds exhibit characteristics of indirect bandgap semiconductors, with fundamental and optical bandgaps spanning from 1.45 to 3.57 eV. Notably, the Cu-based ABO2 compounds display a significantly larger fundamental bandgap and excel as photocathode materials when the B-site element is held constant. Among these, CuInO2 emerges as the most promising candidate, showcasing superior photo­(electro)­catalytic performance. Extensive density functional theory calculations unravel intricate insights into the interplay between the band-edge electronic structure and valence orbital hybridization of the A- and B-site elements, providing invaluable perspectives for comprehending and enhancing the photo­(electro)­catalytic performance of such compounds. The findings in this study not only establish robust theoretical foundations for integrating ABO2 compounds into the field of photo­(electro)­catalysis but also lay the groundwork for future material design and optimization.