Novel microwave-assisted synthesis of porous g-C3N4/SnO2 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.