Covalent-Organic Framework-Manipulated Multi-Reactant Activation Enables Polystyrene Electrodegradation in Tandem...

Polystyrene (PS) waste is exceptionally difficult to chemically degrade under environmental conditions, and the high-value utilization of low-value C₁ products generated during the process has never been achieved. Herein, we constructed a metalloporphyrin-anthracene sp² covalent-organic framework (COF) electrocatalyst, TAPP-Fe^III-An, which displays high structural stability and outstanding capability in activating O₂ and multi-reactants. This enables it to effectively electro-degrade PS into high-value benzoyl products (yield, 23.2%, M_w residue 0.3%) and re-convert 20% of C₁ products into high-value 1-formyl-1,2,3,4-tetrahydroquinoline (anticancer drug intermediate) with 9.4% yield, through a tandem quinoline carbonylation reaction. This breaks the traditional dilemma where PS degradation produces low-value byproducts that are difficult to re-utilize. Electrochemical experiments combined with theoretical calculations reveal that the valence tautomerism (Fe^II-Fe^III-Fe^IV) of metal center and active An ligand endow TAPP-Fe^III-An catalyst with the ability to activate O₂ (generating ¹O₂, •O₂ ^-, and •OH) and multi-reactants (PS and CO), thus enabling efficient PS electrodegradation (to benzoyl products) in tandem with low-value C₁ products carbonylation (to anticancer drug intermediate). In this process, the generated C₁ products (HCOOH, CO) were re-activated by TAPP-Fe^III centers, and then react with 1,2,3,4-tetrahydroquinoline for high-value conversion. This work pioneers a tandem conversion strategy for PS waste degradation and low-value C₁ products upgrading.