Enhanced Visible-Light Degradation of Rhodamine B by Hydrothermally Synthesized WO ₃ @g-C ₃ N ₄ Heterostructures for Water Remediation

Graphitic carbon nitride (g-C₃N₄) is a polymeric semiconductor that has garnered considerable attention in photocatalysis due to its high activity in processes such as the degradation of organic pollutants, water splitting, and CO₂ reduction. Tungsten trioxide (WO₃), a metal oxide semiconductor known for its electrochromic, photochromic, and photocatalytic properties, has shown strong potential for coupling with g-C₃N₄ to enhance visible-light-driven photocatalytic performance. This study investigates the effect of varying WO₃ content (0%, 3%, 5%, 7%, 9%) on the structural and photocatalytic properties of WO₃@ g-C₃N₄ composites for Rhodamine B (RhB) degradation under visible light irradiation. The composites were synthesized via a hydrothermal method and characterized using XRD, FTIR, SEM, TEM, DRS, and PL analyses to evaluate their crystal structure, chemical bonding, surface morphology, band gap energy, and charge carrier dynamics. The results show that increasing WO₃ content modifies the band structure and enhances charge separation efficiency. Photocatalytic tests demonstrated a progressive increase in RhB degradation efficiency with higher WO₃ content, reaching a maximum of 99.7% after 210 min at 9% loading. The catalytic activity was only slightly affected by pH and the presence of reactive species scavengers. The enhanced performance of the 9% WO₃@g-C₃N₄ composite is attributed to improved visible light absorption and reduced electron-hole recombination.