Photocatalytic Sulfur-Rich Covalent Organic Polymers Prepared through an Improved Dual-Solvent-Titration Method

Among various types of photocatalysts, β-ketoenamine-based covalent organic polymers (COPs) are highly favored for the photocatalytic degradation of dyes in wastewater due to their excellent water tolerance, straightforward reaction mechanism, and appropriate optical band gap. However, traditional synthetic methods often necessitate harsh conditions and extended reaction times, while reactions conducted at room temperature typically result in low yields or poor crystallinity of the COPs. Herein, we devised an improved dual-solvent-titration synthesis method that operates at lower temperatures, enabling the production of a series of sulfur-rich COPs with high crystallinity. This method involves dissolving the two monomers in different miscible solvents of good quality and slowly titrating one solution into the other. This process disrupts the interaction between the monomers, resulting in a gradual reaction and the formation of highly crystalline products. The synthesized COPs exhibit photocatalytic properties for the degradation of Rhodamine B, achieving a high conversion rate of up to 93.56% within 50 min. Furthermore, the XD-COPs demonstrate excellent capacity for supporting Pd(OAc)2, suggesting that they represent competitive options for metal supports and heterogeneous catalysts.