Synthesis and Evaluation of g‐C ₃ N ₄ /BiOI S‐Scheme Photocatalyst for Photodegradation of Rhodamine B

This study presents a facile and environmental friendly strategy for synthesizing graphitic carbon nitride/bismuth oxyiodide (g‐C ₃ N ₄ /BiOI) nanocomposites for the efficient photodegradation of Rhodamine B (Rh B) dye under visible‐light irradiation. The g‐C ₃ N ₄ is a promising material for photocatalysis; however, rapid charge carrier recombination prevents its practical application. To address this, a heterojunction was constructed by integrating g‐C ₃ N ₄ with BiOI, a narrow‐bandgap p‐type semiconductor. The g‐C ₃ N ₄ /BiOI nanocomposite was fabricated using pulsed laser ablation in liquid (PLAL) and a simple coprecipitation method. Scanning electron microscopy (SEM) analysis showed that g‐C ₃ N ₄ nanoparticles act as nucleation sites, directing the assembly of BiOI nanoplates into 3D spherical architectures. Optical studies demonstrated a significant redshift of the absorption edge in the composite compared to pristine g‐C ₃ N ₄ , enabling the material to harvest a larger portion of the visible solar spectrum. The g‐C ₃ N ₄ /BiOI nanocomposite achieved an impressive degradation efficiency of 89% in 120 min, compared to 38% for pristine g‐C ₃ N ₄ . This superior activity is attributed to the formation of an efficient S‐scheme heterojunction between the p‐type BiOI and n‐type g‐C ₃ N _4. This mechanism facilitates spatial charge separation by allowing the recombination of lower‐energy electrons and holes at the interface while retaining high redox potential carriers for the generation of reactive oxygen species.