The g-C3N4/C2N Nanocomposite: A g-C3N4-Based Water-Splitting Photocatalyst with Enhanced Energy Efficiency

Water-splitting photocatalysts with good energy efficiency are highly desirable, among which metal-free graphitic carbon nitride (g-C3N4) is considered to be very promising and has been intensively studied in recent years. However, its practical application is hindered by the relatively low efficiencies of visible-light absorption and electron-hole separation. Herein, based on first-principles calculations, it is predicted that, by forming nanocomposites with another carbon nitride (C2N), the energy efficiency of g-C3N4 can be significantly improved. On one hand, C2N has a wide, strong optical absorption in the visible-light region, which acts as a photosensitizer and enhances the photoabsorption efficiency of the composite photocatalyst. On the other hand, C2N forms a type II heterojunction with g-C3N4, which leads to efficient separation of photogenerated electron-hole pairs through the chemical potential difference between the two components. These results provide a potential route to achieve highly efficient metal-free photocatalysts for water splitting.