Novel microwave-assisted synthesis of porous g-C ₃ N ₄ /SnO ₂ nanocomposite for solar water-splitting

Highly porous nanocomposites of graphitic-carbon nitride and tin oxide (g-C ₃ N ₄ /SnO ₂ ) were prepared through simple pyrolysis of urea molecules under microwave irradiation. The initial amount of tin was varied in order to investigate the effect of SnO ₂ content on preparation and properties of the composites. The synthesized nanocomposites were well-characterized by XRD, FE-SEM, HR-TEM, BET, FTIR, XPS, DRS, and PL. A homogeneous distribution of SnO ₂ nanoparticles with the size of less than 10 nm on the porous C ₃ N ₄ sheets could be obtained, suggesting that in-situ synthesis of SnO ₂ nanoparticles was responsible for the formation of g-C ₃ N ₄ . The process likely occurred by the aid of the large amounts of OH groups formed on the surfaces of SnO ₂ nanoparticles during the polycondensation reactions of tin derivatives which could facilitate the pyrolysis of urea to carbon nitride. The porous nanocomposite prepared with initial tin amount of 0.175 g had high specific surface area of 195 m ² g ⁻¹ which showed high efficiency photoelectrochemical water-splitting ability. A maximum photocurrent density of 33 µA cm ⁻² was achieved at an applied potential of 0.5 V when testing this nanocomposite as photo-anode in water-splitting reactions under simulated visible light irradiation, introducing it as a promising visible light photoactive material.