A facile approach for fabricating g-C3N4-based materials as metal-free photocatalysts

This study presents a novel, straightforward approach for synthesizing graphitic carbon nitrides (g-C 3 N 4 , g-CN) from melamine, requiring merely 30 min of thermal holding at temperatures ranging from 400 to 550 °C in an atmosphere comprising either nitrogen or air. Elemental analysis, X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), diffuse reflectance (UV–Vis DRS), photoluminescence (PL) spectroscopy and scanning electron microscopy (SEM) were employed to assess the quality of the as-prepared powders. Furthermore, theoretical calculations utilizing the Density Functional Theory (DFT) method were conducted to reinforce the experimental findings of the research. A further investigation of the thermal stability of the selected sample was conducted using a unique combination of thermogravimetry–coupled with differential scanning calorimetry, quadrupole mass spectrometry (TG-DSC-MS) and advanced temperature-programmed desorption (TPD) analyzes. The current study focuses on the effect of synthesis conditions (temperature and nitrogen/air environment) on the structure, morphology, and photocatalytic performance of g-C 3 N 4 compounds synthesized using this approach. The g-C 3 N 4 -based materials were examined as potential photocatalysts using the acid orange 7 (AO7) photodegradation methodology. To enable comparison of the photodegradation experiments, two separate lamps with wavelengths of 360 nm (UV light) and 420 nm (VIS light) were utilized. The primary objective was to present a novel method for the synthesis of g-C 3 N 4 -based materials. This was achieved by demonstrating that organic composites generated at lower temperatures have the best photocatalytic capabilities. Furthermore, the approach to achieving high-quality photocatalysts was shown to be cost-effective, environmentally friendly, and scalable. Graphical abstract: • A new facile approach was developed to obtain g-C 3 N 4 from melamine. • The process involved 30 min of thermal treatment in nitrogen/air at 400–550 °C. • DFT theoretical calculations supported the experimental part of the research. • Photodegradation activity, effect of scavengers of AO7 under UVA/VIS light were observed. • Organic composites with lower temperatures displayed the highest photocatalytic properties.