Synthesis of porous few-layer carbon nitride with excellent photocatalytic nitrogen fixation

The porous few-layer g-C3N4 (PFL-g-C3N4) is prepared by a simple molecular self-assembly method. Compared with pure g-C3N4, the as-prepared PFL-g-C3N4 is ultrathin, the surface is rich in pores, and the photocatalytic nitrogen fixation activity is greatly increased to 8.20 mM h−1 gCat−1. Few-layer and ultrathin nature of PFL-g-C3N4 can provide a larger specific surface area, expose more active sites, and reduce the diffusion path of charges and protons from the inside to the surface. In addition, the porous structure can narrow the band gap, thereby increasing the light absorption range and enhancing the light absorption capability. Meanwhile, the presence of nitrogen vacancies causes PFL-g-C3N4 to move to a more negative conductive band value. More importantly, the isotopic experiments using 15N2 as nitrogen source confirm the ammonia production originating from N2 rather than the decomposition of g-C3N4. Therefore, PFL-g-C3N4 can greatly improve the efficiency of visible light photocatalytic nitrogen fixation.