A carbazole-based fully conjugated sp2c D–A covalent organic polymer for visible light mediated photocatalytic degradation of rhodamine B and Rose Bengal†

Abstract

Two-dimensional covalent organic materials have great potential as photocatalysts, but for practical application, they have some limitations like scalability and stability. Nevertheless, ongoing research efforts aim to address these challenges and unlock their full potential for sustainable photocatalysis. In this study, we have developed sp² carbon-linked and imine-linked 2D donor–acceptor CzTA-PDAN and CzTA-PDA COPs. Notably, the sp² carbon-linked CzTA-PDAN COP demonstrates superior charge separation, rapid photocurrent response, and excellent chemical stability compared to the imine-linked CzTA-PDA COP, owing to its fully conjugated robust structure. The band gap calculated from the Kubelka–Munk plot was 2.30 eV and 2.53 eV, respectively, which resulted in the sp²c CzTA-PDAN COP having a higher electron carrier transport efficiency. Leveraging its favorable photo and optoelectronic properties, we employed the CzTA-PDAN COP for the photocatalytic degradation of organic toxic dyes, rhodamine B and Rose Bengal, under 18 W white CFL illumination for 80 minutes and 390 minutes, respectively. Additionally, the sp² carbon-linked CzTA-PDAN COP exhibited exceptional degradation performance even under sunlight, achieving complete degradation of the RhB dye within 60 minutes of irradiation. This highlights the practical applicability and versatility of the CzTA-PDAN COP in environmental remediation scenarios. By harnessing the unique properties of COPs, such as those demonstrated by the sp² carbon-linked CzTA-PDAN COP, we can pave the way for their widespread adoption in sustainable photocatalysis applications.