Nitrogen defects and porous self-supporting structure carbon nitride for visible light hydrogen evolution

Abstract

The photocatalytic performance of a catalyst can be effectively enhanced by adjusting the structure of graphitic carbon nitride (g-C₃N₄). Porous self-supporting carbon nitride (PSCN) was synthesized through supramolecular self-assembly using pure carbon nitride (PCN) as a precursor. PSCN has a self-supporting porous structure with a specific surface area of 58.50 m² g⁻¹. This feature effectively enhances the contact between the catalyst and the reactant, providing an abundance of reactive active sites. The C/N atomic ratio of PSCN (0.980) measured by XPS is higher than that of PCN (0.785), and the EA test results are consistent with this, indicating N-defects in the skeleton structure of PSCN. Meanwhile, DFT calculations were used to identify the locations of N-defects in the framework structure of PSCN. The presence of N-defects in PSCN can optimize the surface electronic structure, thereby enhancing photoexcited carrier separation efficiency. Therefore, PSCN exhibits higher performance in visible light-driven hydrogen evolution, which is 7.8 times greater than that of PCN. These findings offer a straightforward and efficient approach to enhance the photocatalytic performance of g-C₃N₄ through structural modification and morphological engineering.