One-pot construction of chitin-derived carbon/g-C₃N₄ heterojunction for the improvement of visible-light photocatalysis

Graphitic carbon nitride (g-C₃N₄), as a class of metal-free photocatalyst, possesses advantageous features, such as renewability, visible-light-response, and so on. However, the obstacles of high charge recombination rate and low surface area limit its practical application. In the present work, we developed an economic and eco-friendly method to in situ construct chitin-derived carbon/g-C₃N₄ heterojunction (CDC/CN) to inhibit the charge recombination and increase the surface area. The structure–function relationship is studied by XRD, HRTEM, PL spectra, DRS and photoelectricity test. It revealed that the heterojunction has multi-functions in enlarging photoharvesting, reducing the band gap, and recombination rate, which are essential to improve the photocatalytic performance. As the doping precursor, chitin can adjust the terminal group and microstructure of g-C₃N₄ due to the unbalance of electron density in the thermal polymerization of urea, leading to nearly 10 times increment of the surface area of g-C₃N₄. Subsequently, visible-light-induced degradation of Rhodamine B, a normal dye pollutant, was investigated to examine the catalytic activity, where the modified g-C₃N₄ exhibited significant enhancement of both photocatalytic activity and reaction rate in comparison with the pristine g-C₃N₄.