Abstract:

The foam-like graphitic carbon nitride(g-C₃N₄) was synthesized by using melamine as the raw material and cheap sepiolite as the hard template, respectively. The as-prepared samples were characterized by transmission electron microscopy(TEM), X-ray diffraction(XRD), Fourier transform infrared(FT-IR) spectrometry, Brunauer-Emmett-Teller(BET) method, ultraviolet-visible diffuse reflectance spectroscopy(UV-Vis DRS), photoluminescence(PL) spectroscopy and electrochemical measurements, and the photocatalytic activity was evaluated by visible light driven hydrogen evolution. The results show that polydopamine can act as adhesives,which can improve the combined degree between the template and melamine, leading to the increase of the specific surface area of foam-like graphitic carbon nitride. Furthermore, the specific surface area of the obtained sample increases with the increase of polydopamine-modified sepiolite, when the mass ratio of polydopamine-modified sepiolite and melamine is 2:1, the specific surface area of the foam like g-C₃N₄ is as high as 389.2 m²/g and the visible light driven H₂ evolution rate can reach up to 1061.87 μmol/(g·h), which is ~7 times greater than that of bulk g-C₃N₄(151.24 μmol/(g·h)) and 2.6 times higher than that of g-C₃N₄ synthesized by unmodified sepiolite, respectively. This indicates that the foam-like g-C₃N₄ with a large surface area can provide more active sites and improve the diffusion process of multi-phase photocatalytic reaction, enhancing the separation efficiency of photogenerated electrons and holes. Additionally, the unique cavity structure can also effectively improve the utilization of light, leading to a significant improvement in the photocatalytic performance.

Key words: foam-like graphitic carbon nitride, visible light driven hydrongen evolution, sepiolite