Defect Engineering in Atomic-Layered Graphitic Carbon Nitride for Greatly Extended Visible-Light Photocatalytic Hydrogen Evolution.

Defect modulation usually has a great influence on the electronic structures and activities of photocatalysts. Here, atomically layered g-C3N4 modified via defect engineering with nitrogen vacancy and cyanogen groups is obtained through two facile steps of thermal treatment (denoted as A-V-g-C3N4). Detailed analysis reveals that the atomic-layered graphitic carbon nitride (2.3 nm) with defect engineering modifying provides more active sites and decreases the electron/hole transferring distances. More importantly, the defects that contain nitrogen vacancies and cyanogen groups extend the responsive wavelength to 650 nm, which effectively suppresses the quantum size effect of atomic-layered g-C3N4. Therefore, the as-obtained A-V-g-C3N4 exhibited a photocatalytic H2 evolution rate and apparent quantum yield of 3.7 mmol·g-1·h-1 and 14.98% (λ > 420 nm), respectively. This work is expected to provide guidance for the rational design of atomic-layered g-C3N4.