Engineering electron-and ion-transporting active pore channels in ultrathin covalent organic framework nanosheets for enhanced photocatalysis

Abstract

The construction of porous photocatalysts with high-density active sites accessible to both electrons and ions is crucial for enhancing photocatalytic efficiency and improving the economic feasibility. Here, we report a pore-partitioning strategy that establishes dedicated pathways for ions and electrons within the pore channels, simultaneously enhancing ion diffusion, charge mobility, and active-site density. As a proof of concept, a covalent organic framework (COF) was designed to incorporate metalloporphyrin motifs within its micropores, wherein the metalloporphyrin-COF interface establishes dense reaction centers with efficient electron-transfer chain, while the remaining pore space, functionalized with hydrophilic ionic groups, serves as aligned conduits for rapid ion supply. Fine-tuning the electron- and ion-transport domain dimensions via coordination control enables optimized bicarbonate ion conductivity (1.5 mS cm-1), extended charge-separation lifetime (1.76 ns), and high-efficiency CO2 photocatalytic reduction to CO (5314 μmol g-1 h-1). By elucidating ultrafast reaction dynamics and demonstrating broad applicability, this work provides a generalizable design principle for advanced photocatalysts.