Synergistic strategies of metallization and redox coupling to enhance the quantum yield and recyclability of porphyrin COF

Abstract

Enhancing the quantum efficiency of photocatalytic reactions and recyclability of photocatalysts are crucial for the practical applications of photocatalytic technology. In this study, a mechanical grinding method was employed to prepare porphyrin covalent organic framework (Por-COF) and metalloporphyrin covalent organic frameworks (MPor-COF, M = Zn, Fe). These COFs were evaluated for their photocatalytic and recycling performances under visible light. ZnPor-COF exhibited a significant enhancement in quantum efficiency compared to Por-COF, with efficiency increases of 31.8 %, 3.0 %, and 11.5 % for individual reduction, individual oxidation, and simultaneous redox reactions, respectively. Notably, when ZnPor-COF underwent simultaneous redox reactions with oxidation and reduction efficiencies above 80 %, the number of recycles increased from 3 to 10 times compared to Por-COF. This synergistic strategy of metallization and redox coupling improved the photocatalytic and recycling performance of Por-COF. Experimental and theoretical investigations revealed that the introduction of metal ions enhance light response, altere energy levels, reduce carrier separation distance, and improve carrier separation performance. Simultaneous oxidation and reduction reactions effectively mitigated photocorrosion, enhancing stability and carrier utilization efficiency. This research provides valuable insights for advancing porphyrin-based COF photocatalytic technology.