Impact of Thermal Conditions on the Structural, Morphological, and Optical Behavior of Graphitic Carbon Nitride

Abstract

To investigate the influence of the synthesis temperature on its structural, morphological, and optical properties, graphitic carbon nitride (g-C₃N₄) was prepared by thermal polycondensation of melamine at temperatures of 300 °C, 400 °C, and 500 °C. XRD, SEM, FTIR, and UV-Vis spectroscopy were used to characterize the produced samples. The XRD analysis revealed that the crystal structure increased in terms of crystallinity with the increase in temperature as indicated by the enhanced (002) diffraction peak. The morphology of SEM micrographs changed to discrete nanosheets at 500 °C, whereas at 300 °C agglomerate was observed to be dense. The FTIR spectroscopy showed that more polycondensation occurred at higher temperatures and the tri-s-triazine structure was maintained. In UV-Vis studies, temperature-dependent optical behaviour was found, where a periodic redshift of the absorption edge was observed with increase in temperature. The findings indicate that, 500 °C is the optimum temperature to form highly condensed, crystal form of g-C3N4 with a higher structural order and variation in light harvesting qualities.