Carbon Nanofiber-Bridged Carbon Nitride-Fe2O3 Photocatalyst: Hydrogen Generation and Degradation of Aqueous Organics

Abstract

Graphitic carbon nitride (g-C₃N₄)-supported ferric oxide (Fe₂O₃) nanocomposite modified with carbon nanofibers (CNFs) has been synthesized for the first time for photocatalytic H₂-generation and the degradation of aqueous organics. In its first dual role, Fe₂O₃ served as the photocatalyst and the chemical vapor deposition (CVD) catalyst to grow CNFs over the g-C₃N₄ substrate. Time of CVD was found to be critical for synthesizing Fe₂O₃-CNF/g-C₃N₄ with a good photocatalytic efficiency. The synthesized materials were characterized for various physicochemical and photocatalytic properties. The creation of a Z-scheme heterostructure between g-C₃N₄ and Fe₂O₃ resulted in the greater H₂-generation rate (2095 µmol/g h) than that (1119 µmol/g h) over the substrate. The photocatalytic degradation data showed ~ 95 and 91% removal of methylene blue and 4-nitrophenol in 180 and 300 min, respectively at 22 °C using the Fe₂O₃-CNF/g-C₃N₄ dose of 0.5 mg/mL. The photocatalytic reactions followed the indirect Z-scheme charge transfer path, with the graphitic CNFs acting as the electron-transfer medium between Fe₂O₃ and g-C₃N₄. The simple fabrication route and high photocatalytic efficiency of the ternary CNF-bridged Fe₂O₃-g-C₃N₄ composite system indicate the utility of the material in integrated environmental and energy applications including microbial fuel cells and microelectrolysis cells.