Synthesis and photocatalytic improvement for methylene blue degradation of MgO/g-C3N4 and ZnO/g-C3N4 composites

Abstract This work investigates the synthesis of pristine graphitic carbon nitride (g-C 3 N 4 ), ZnO/g-C 3 N 4 , and MgO/g-C 3 N 4 composites through a direct thermal pyrolysis method using urea and metal oxides. X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope with EDS were employed to confirm the formation and structural features of the materials. Diffuse reflectance spectrometry (DRS) analysis showed that the energy band gap of the g-C 3 N 4 ​ composite increased with the addition of ZnO but decreased with MgO incorporation. Photocatalytic performance was assessed by monitoring the degradation of methylene blue (MB) under visible light irradiation. The results indicate a significant improvement in photocatalytic activity for both composites compared to pure g-C 3 N 4 ​. Specifically, the ZnO/g-C 3 ​N 4 ​ composite raised MB degradation efficiency from 50% to 86%, while the MgO/g-C 3 ​N 4 ​ (10%) composite achieved the highest efficiency, reaching 99% degradation after 120 min. The superior performance of these composites is attributed to enhanced charge separation and transfer facilitated by the metal oxides. These findings suggest that MgO/g-C 3 N 4 ​ is a highly promising photocatalyst for wastewater treatment applications. The primary aim of this study is to compare the photocatalytic performance of pristine graphitic carbon nitride (g-C 3 N 4 ​) with its composites containing zinc oxide (ZnO) and magnesium oxide (MgO). The research investigates how the addition of these metal oxides impacts the structural, optical, and photocatalytic properties of g-C 3 N 4 . Ultimately, the study evaluates the efficiency of all three materials g-C 3 N 4 ​, ZnO/g-C 3 N 4 , and MgO/g-C 3 N 4 ​ in degrading methylene blue (MB) under visible light.