Exploring the evolution patterns of melem from thermal synthesis of melamine to graphitic carbon nitride

Abstract

In the exploration of synthesizing graphitic carbon nitride (g-C₃N₄), the existence of secondary anime bridging units shows the incompleteness of related theories. Thus, taking the thermal synthesis of melamine as an example, this work finds a possible reaction path with Density Functional Theory (DFT) for forming melem during the thermal synthesis of g-C₃N₄. Combined with transition state theory (TST), it indicates that the formation of melem results from the condensation of melamine and isomerization of melam. Meanwhile, the weak signal near 2135 cm⁻¹ in the Fourier Transform Infrared Spectra (FTIR) corresponds to the vibration of carbodi-imines (–NCN–), which further proves the proposed reaction path. Thus, this work can explain the formation of g-C₃N₄ and its monomer, which may contribute to the successful formation of ideal g-C₃N₄ in the future.