Construction of 2D/3D g-CN/BiOI Photocatalysts with p-n Heterojunction and Their Performance in Photocatalytic Degradation of Amaranth Dye.

The g-CN (graphitic carbon nitride)/BiOI (bismuth oxyiodide) photocatalysts, boasting a unique nanomicrosphere architecture, were synthesized through a tripartite process involving heat polycondensation, hydrothermal treatment, and hybrid methods, using melamine, bismuth nitrate, and potassium iodide as starting materials. The photocatalyst was comprehensively characterized and analyzed while its efficacy in photocatalytic degradation of amaranth (AR) under various lighting conditions was investigated, and the catalytic mechanism was determined by kinetic analysis and free radical scavenging experiments. The results showed that g-CN formed a strong bond with BiOI. The resulting composite catalyst retains the inherent 2D lamellar structure of g-CN, as well as the 3D microsphere structure of BiOI, thereby creating heterojunctions via p-n interactions. Under visible light exposure, g-CN/BiOI-15% demonstrated optimal catalytic performance, achieving a degradation rate of 74.64% for AR and exhibiting the highest rate constant. Radical tests confirmed that -O (superoxide anion) plays a crucial role as active species in the photocatalytic reaction.