Large-Scale Preparation of g-C3N4 Porous Nanotubes with Enhanced Photocatalytic Activity by Using Salicylic Acid and Melamine

Graphitic carbon nitride (g-C3N4) nanotubes were produced by using salicylic acid-mediated melamine successfully. The obtained long g-C3N4 nanotube possesses a large specific surface area and a parallel channel structure. Salicylic acid and its decomposition products present in g-C3N4 influenced its formation process and inhibited the crystal growth of g-C3N4. A possible mechanism is proposed: Salicylic acid and its decomposition products facilitated the formation of g-C3N4 nanosheet, and then the nanosheet coiled to form a nanotube. The tube-like structure facilitates the increase in photocatalytic activities, which are 6.7 and 2.4 times that of pristine g-C3N4 in 2-propanol decomposition and CO2 photoreduction, respectively. The enhanced photocatalytic performance was contributed by the large specific surface area, better photogenerated charge carrier transmission, and the porous nanotube structure. This research provides an easy synthetic method for the large-scale production of g-C3N4 nanotubes applied in the photocatalytic field.