Intercalation–engineered g–C3N4/kaolinite composites with enhanced charge separation for ciprofloxacin degradation

Interlayer engineering of mineral supports offers an effective yet still underexplored approach for regulating the electronic structure of semiconductor photocatalysts. In this study, an intercalation–mediated interface engineering strategy was proposed, in which g–C 3 N 4 were coupled with kaolinite pre–intercalated using small organic molecules to achieve directional modulation of the g–C 3 N 4 structure. Among the resulting composites, the potassium acetate–derived sample (CN/K–KL) uniquely enabled simultaneous K + incorporation and the formation of cyano groups, leading to rapid ciprofloxacin degradation (91.7%) within 60 min accompanied by a high ·O 2 − yield (41.08 μM). Mechanistic investigations combining density functional theory (DFT) calculations and experimental results revealed that these structural features improved charge separation, enhanced O 2 adsorption, and effectively lowered the kinetic energy barrier for H 2 O 2 activation, thereby enabling an efficient carrier–driven, metal–free, light–activated H 2 O 2 activation pathway. This work highlights the critical role of intercalation engineering in regulating mineral microenvironments and optimizing semiconductor charge kinetics, challenging the conventional view of minerals as supports. Moreover, it provides a rational design strategy for precise structural modulation of g–C 3 N 4 and the construction of high–performance, non–metallic photocatalytic systems.