Double defects modified carbon nitride nanosheets with enhanced photocatalytic hydrogen evolution.

Graphitic carbon nitride (g-C3N4) is an actively investigated metal-free photocatalyst for solar energy conversion. However, primary g-C3N4 usually exhibits limited utilization of visible light and fast combination of photoexcited charge carriers, resulting in low photocatalytic H2 evolution activity. Defect-modified g-C3N4 shows much enhanced photocatalytic H2 evolution activity owing to extended light absorption as well as efficient charge separation and transfer. Here, the photocatalyst simultaneously containing nitrogen vacancies and O-doping is successfully developed by using a two-step post-synthetic strategy for photocatalytic H2 evolution, resulting in a greatly-boosted H2 evolution activity (1.69 × 103 μmol g-1 h-1) compared with that of pristine g-C3N4 (1.12 × 102 μmol g-1 h-1). It is believed that the newly developed double-defect strategy may open an avenue toward obtaining molecular level comprehension of the function of a catalyst in photocatalytic H2 evolution and can be extended to the modification of other semiconductors.