Carbon nitride nanotubes with in situ grafted hydroxyl groups for highly efficient spontaneous H₂O₂ production

An active and inexpensive photocatalyst for H₂O₂ production is desirable for industrial applications. However, obtaining high photocatalytic activity from metal-free catalysts without the use of sacrificial electron donors is difficult. Herein, g-C₃N₄ (CN) nanotubes functionalized with surface > OH groups that are grafted in situ were successfully synthesized via a novel alkalinization process. The nanotube structures provide a large surface area and improved mass transfer properties. In situ grafted > OH groups can capture photogenerated holes to promote separation of photogenerated charge, enabling the ready availability of electrons and hydrogen ions for H₂O₂ production. Further, the surface > OH groups help to suppress H₂O₂ self-decomposition. Consequently, a high rate of 240.36 μmol h⁻¹ g⁻¹ of H₂O₂ production can be achieved without sacrificial agents, which is the highest H₂O₂ production in a spontaneous system for metal-free photocatalysts. This work provides a new strategy for an efficient and spontaneous H₂O₂ production method using a metal-free CN photocatalyst.