Graphitic C2N3: An Allotrope of g-C3N4 Containing Active Azide Pentagons as Metal-Free Photocatalyst for Abundant H2 Bubble Evolution

A g-C3N4 allotrope, a curved leaf-like graphitic C2N3 (g-C2N3) with an intrinsic spontaneous polarization electric field (ISPEF), has been constructed for efficient solar energy conversion into H-2 energy via photocatalytic H2O splitting. The curved leaf-like pi-delocalization g-C2N3 was composed of aromatic azide pentagons and normal triazine hexagons obtained by cycloaddition between -C N groups from dicyandiamide polymerization and azide from the heat-treated polypyrrole fibers. Under light irradiation (lambda > 420 nm), photo-generated charges are driven to separate efficiently and transfer from bulk to active sites of the surface under ISPEF that is opposite to the Coulomb field. Consequently, without any cocatalyst, g-C3N4 allotrope demonstrates a very high H-2-production activity of 14.9 mmol g(-1) h(-1) accompanied by a lot of H-2 bubbles, which is 2.6 times of g-C3N4 loading with Pt. In comparison with the reported metal-free photocatalysts or those supported with noble metals, g-C3N4 allotrope (i.e., leaf-like g-C2N3) is confirmed to be the best metal-free photocatalyst for H2O splitting into H-2 fuel so far. The contructed leaf-like g-C2N3 with SPEF supplies a suitable platform for solar energy conversion into H-2 fuel, which actively contributes to clean energy production.

Automated summary

By constructing a g-C3N4 allotrope with intrinsic spontaneous polarization electric field, efficient conversion of solar energy into H-2 energy via photocatalytic H2O splitting has been achieved. The leaf-like g-C2N3 material exhibits high H-2 production activity under light irradiation, making it an excellent metal-free photocatalyst for clean energy production.