Novel (Na, O) co-doped g-C3N4 with simultaneously enhanced absorption and narrowed bandgap for highly efficient hydrogen evolution

- Solvothermal method was introduced to modify bulk g-C3N4.
- High crystalline and dispersive (Na, O) co-doped g-C3N4 was obtained.
- The absorption of both the UV and visible light for (Na, O)-g-C3N4 was enhanced obviously compared with bulk g-C3N4.
- The photocatalytic activities of (Na, O)-g-C3N4 is improved with the apparent quantum yield as high as 22.3% at 420 nm.

The photocatalytic activity of bulk g-C3N4 is rather low. Many strategies have been adopted to improve the photocatalytic performance of g-C3N4. Here, Na and O co-doped g-C3N4 was prepared by a feasible solvothermal method. The band structure was modulated mainly by introducing O into lattice of g-C3N4, resulting in simultaneously enhanced absorption and red shift. Moreover, the separation and migration of photogenerated carriers under visible light was enhanced by Na doping. In addition, well dispersion of (Na, O)-g-C3N4 in pure water was observed due to its high surface electronegativity. The photocatalytic H2 production activity of (Na, O)-g-C3N4 was improved tremendously, especially under visible light, and the apparent quantum yield was as high as 22.3% at 420 nm.

126