Uracil-Doped Graphitic Carbon Nitride for Enhanced Photocatalytic Performance

g-C₃N₄ is a visible-light photocatalyst with a suitable band gap and good stability. Moreover, g-C₃N₄ is considered to be earth-abundant, which makes it an appealing photocatalyst. However, due to its small specific surface area, low utilization of visible light, and high photogenerated electron-hole pair recombination rate, the photocatalytic activity of g-C₃N₄ remains unsatisfactory. In this work, a highly efficient nonmetallic photocatalyst, i.e., g-C₃N₄ doped with uracil (denoted U-C₃N₄) was successfully developed. Based on the various characterizations and calculations, it is shown that the triazine group in g-C₃N₄ is replaced with the diazine group in uracil. This occurrence leads to the formation of a new electron-transfer pathway between triazine groups, which can promote the separation of photogenerated electrons and holes. Concurrently, due to the ultrathin structure of the as-prepared U-C₃N₄, the material possessed a larger specific surface area than pristine g-C₃N₄, which can provide more active sites. Furthermore, the transfer pathway between the electron and hole was also shortened, and the recombination of the electron and hole was inhibited. According to the results, an optimal hydrogen evolution rate of 31.7 mol h^-1 g^-1 was achieved by U-C₃N₄, which is 5.1 times higher as compared to that achieved by pristine g-C₃N₄ (6.26 mol h^-1 g^-1). For the photocatalytic degradation of rhodamine B, the reaction rate constant of U-C₃N₄ (11.3 × 10^-2 min^-1) is about 5.5 times that of g-C₃N₄ (2.07 × 10^-2 min^-1). Furthermore, the uracil-doped catalyst was also able to demonstrate good stability after five successive runs.