Fe single-atom-modified g-C ₃ N ₄ via a facile oxygen-tolerant synthesis strategy for improved photocatalytic H ₂ production

Single-atom catalysts based on graphitic carbon nitride (g-C₃N₄) show high potential for hydrogen production photocatalytically. However, it is still a challenge to develop single-atom-based g-C₃N₄ due to the complex synthesis procedures, limited active sites, and insufficient mechanistic understanding. Herein, a facile oxygen-tolerant synthesis strategy was developed that utilizes the nitrogen-rich structure of g-C₃N₄ to capture Fe single atoms from ammonium iron citrate, successfully constructing an efficient photocatalytic composite. The resulting Fe single-atom-modified g-C₃N₄ catalyst exhibited highly improved light absorption, charge carrier separation, and a substantially enhanced rate of H₂ production photocatalytically under visible light irradiation. Experimental results demonstrated that the optimal sample achieves a H₂ production rate of 683 μmol h^-1 g^-1, representing a 425% enhancement compared to pristine g-C₃N₄. This study presents a facile oxygen-tolerant approach for metal immobilization using metal-organic precursors, where the nitrogen-rich framework of g-C₃N₄ effectively captures Fe atoms as singular site within the composite. The developed synthesis strategy provides new insights for designing high-performance single-atom photocatalytic materials, potentially advancing the application and development of photocatalysis.