Enhanced Photoluminescence of Porous Silicon functionalized with Congo Red for chemical sensing applications

Congo Red (CR), an anionic dye widely used as a pH indicator, is successfully incorporated into Porous Silicon (PS). We investigated the enhanced photoluminescence (PL) properties of the resulting nanocomposites (PS/CR) by analyzing the effects of different impregnation times and dye concentrations. When exposed to acidic vapors such as HCl, the PL spectrum exhibits a red shift, while subsequent exposure to ammonia restores the initial state, highlighting the complete reversibility of the process and evidencing their suitability for gas sensing applications.