Switching g-C3N4 morphology from double-walled to single-walled microtubes induced high photocatalytic H2-production performance

Abstract It is a huge challenge to find a green, simple and template-free strategy to construct metal-free graphitic carbon nitride (g-C3N4) with a special morphology to improve its performance in photocatalytic hydrogen evolution (PHE). In this study, we discover a facile method to switch the g-C3N4 morphology from bulk (Bg-C3N4) to tubes (Tg-C3N4) by melamine and cyanuric acid self-assembly to improve the PHE performance. Scanning electronic microscopy (SEM) images clearly show switching the Tg-C3N4 morphology from double-walled to single-walled microtubes. In addition, the experimental results suggest that compared to the Bg-C3N4, Tg-C3N4 not only has a large specific surface area but also exhibits a fast separation of charge carriers. Meanwhile, relative to Bg-C3N4, Tg-C3N4 can effectively improve the absorption of light and adjust the bandgap energy of g-C3N4. Excitedly, the obtained Tg–C3N4–0.2 displays the best PHE performance (967.93 μmol h−1 g−1 λ＞420 nm), which is approximately 20.95-fold greater than that of Bg-C3N4. This work offers a promising idea for developing high-efficiency photocatalysts by switching the morphology.