Ordered and Ultralong Graphitic Carbon Nitride Nanotubes Obtained via In-Air CVD for Enhanced Photocatalytic Hydrogen Evolution

Abstract

Metal-free graphitic carbon nitride (g-C3N4) has become one of the most up-and-coming photocatalyst candidates for the hydrogen evolution reaction. However, the improvement in photocatalytic property is strongly suppressed by the limited active reaction sites due to the bulk microstructure of g-C3N4. On this basis, we exploit a moderate and economical approach to prepare an ordered and one-dimensionally ultralong carbon nitride nanotube (CN-NT) via the in-air chemical vapor deposition (CVD) with SiO2 nanofiber templates synthesized by electrostatic spinning. Due to the uniform size, fluffiness, and easy removal, SiO2 nanofiber templates are conducive to prepare ordered and tubular CN-NT. The obtained CN-NT sample exhibits an excellent photocatalytic hydrogen evolution rate (HER) of 4605.2 μmol·h–1·g–1 under visible light, which is 33.4 times higher than that of the original bulk g-C3N4. The apparent quantum efficiency reaches 6.49% at 420 nm. The enhancement in the photocatalytic activity is ascribed to the increased specific surface area, faster electron transfer pathway, advanced light absorption ability, and furthermore the lower recombination rate of photogenerated electrons.