Temperature-tuned synthesis of g-C3N4 for efficient visible light driven nitro-Mannich reactions

Visible light-driven nitro-Mannich reaction using graphitic carbon nitride (g-C 3 N 4 ) photocatalyst addresses significant environmental issues caused by traditional synthesis routes that often involve toxic reagents and harsh conditions. g-C 3 N 4 was synthesized via thermal polymerization of urea and dicyandiamide precursors at different temperatures (260°C, 360°C, 460°C, and 560°C). Among these, g-C 3 N 4 synthesized at 460°C under 200 W white LED demonstrated the best catalytic performance, achieving excellent conversion of 98.06% and selectivity of 90.50% in the reaction. The synthesized g-C 3 N 4 samples were thoroughly characterized by FTIR, XRD, XPS, FE-SEM, HR-TEM, UV-DRS, EIS, and Mott-Schottky analyses to confirm the structure, morphology, optical properties, and electrochemical characteristics of the catalyst. The photocatalyst demonstrated promising reusability, maintaining its activity through five consecutive reaction cycles, highlighting its potential for sustainable and environmentally friendly organic synthesis applications. This approach offers a green alternative to conventional nitro-Mannich reactions with visible light photocatalysis over metal-free g-C 3 N 4 catalysts.