Metal-Free Graphene/Conjugated Microporous Polymer Mott–Schottky Heterojunctions: A Design Strategy for High-Efficiency, Durable Photocatalysts

Conjugated microporous polymers (CMP) are advanced photocatalytic systems for degrading organic dyes. However, their potential and efficiency are often limited by rapid electron–hole pair (e−/h+) recombination. To overcome this limitation, this study proposes a strategy that involves designing a Mott–Schottky heterojunction and integrating graphene sheets with a near-zero bandgap into the CMP-1 framework, resulting in a non-covalent graphene/CMP (GCMP) heterojunction composite. GCMP serves two main functions: physical adsorption and photocatalytic absorption that uses visible light energy to trigger and degrade the organic dye. GCMP effectively degraded four dyes with both anionic and cationic properties (Rhodamine B; Nile Blue; Congo Red; and Orange II), demonstrating stable recyclability without losing its effectiveness. When exposed to visible light, GCMP generates reactive oxygen species (ROS), primarily singlet oxygen (1O2), and superoxide radicals (•O2), degrading the dye molecules. These findings highlight GCMP’s potential for real-world applications, offering a metal-free, cost-effective, and environmentally friendly solution for wastewater treatment.