InSe Monolayer: Promising Cocatalyst of g-C₃N₄ for Water Splitting under Visible Light

Graphitic carbon nitride (g-C3N4) is considered to be a promising material for water splitting and has been intensively investigated in recent years. However, its commercial application is limited due to the low efficiencies of optical absorption and electron–hole separation. Herein, based on the first-principle simulations, we predict that strain tuned g-C3N4/InSe and bilayer g-C3N4/InSe hetrostructures can significantly promote the photocatalytic activity of isolated g-C3N4. Our results demonstrate that the proposed heterostructures possess direct bandgaps, tunable electronic properties, type-II band alignment, and efficient optical absorption. In addition, using the nonequilibrium Green’s function method within the framework of density functional theory (NEGF-DFT), the photoinduced current of the composites is evaluated. Surprisingly, the predicted photocurrent under the visible-light radiation is up to 2.9 μA/mm2 in our proposed heterostructures, which is far superior to other g-C3N4-based composites. These findings suggest that the InSe sheet is a promising candidate as a cocatalyst for the g-C3N4 photocatalyst, which provides valuable hints for experimental design of the visible-light-driven photocatalysts for water splitting with high efficiency.