Two-dimensional g-C3N4/Ti2CO2 heterostructure as a direct Z-scheme photocatalyst for water splitting: A hybrid density functional theory investigation

By using first-principles calculations based on hybrid density functional theory, we investigate the electronic structures and photocatalytic properties of two-dimensional (2D) g-C3N4/Ti2CO2 van der Waals (vdW) hetero-structure. Results show that g-C3N4/Ti2CO2 heterostructure has a staggered type-II band alignment, and a built-in electric field is formed at the interface due to significant charge transfer from g-C3N4 to Ti2CO2. Interestingly, we observed spatially distinguished conduction band and valence band edges, and a direct Z-scheme photocatalytic mechanism can be established in the heterojunction, favorable for suppressed charge carrier recombination. We further demonstrate high catalytic activity of g-C3N4/Ti2CO2 towards both hydrogen evolution and water oxidation reactions, and the heterojunction exhibits excellent light-harvesting capability with entire visible light absorption. These results not only provide fundamental insight into the photocatalyst with Z-scheme mechanism, but also shed light on future design and fabrication of 2D vdW heterojunctions as high-performance catalysts for technologically important chemical reactions.