Synergistic Sodium and Oxalic Acid Engineered g-C₃N₄ Hydrogel Beads for Efficient Visible-Light-Driven Rhodamine B Degradation

Abstract

Graphitic carbon nitride (g-C₃N₄) has emerged as a promising metal-free photocatalyst for environmental remediation; however, its practical application is limited by rapid recombination of photogenerated charge carriers and low surface activity. In the present work, sodium and oxalic acid modified graphitic carbon nitride (NaOCN) was successfully synthesized via a facile modification approach to enhance the photocatalytic performance of pristine g-C₃N₄. The synthesized photocatalyst was systematically characterized using XRD, FTIR, UV–Vis DRS, PL, SEM/TEM, and BET analyses to investigate its structural, optical, and morphological properties. The NaOCN photocatalyst exhibited enhanced visible-light absorption, improved charge separation efficiency, and increased surface active sites compared to pristine g-C₃N₄. The photocatalytic activity was evaluated through degradation of Rhodamine B dye under visible-light irradiation. The modified NaOCN catalyst demonstrated significantly enhanced degradation efficiency owing to synergistic effects of sodium incorporation and oxalic acid induced structural modification. Reactive species trapping studies revealed that superoxide radicals and photogenerated holes played dominant roles during the degradation process. The improved photocatalytic activity indicates that NaOCN is a promising and sustainable photocatalyst for wastewater treatment and environmental purification applications.