Steering Electron Transport in Intrinsically Piezoelectric Covalent Organic Frameworks for Efficient CO ₂ Reduction

Abstract

ABSTRACT Photocatalytic CO 2 reduction represents a transformative route to sustainable fuels, yet remains limited by sluggish charge separation and rapid carrier recombination. Here, an intrinsically piezoelectric porphyrin‐based covalent organic framework anchored with zinc single atoms (Zn‐Por‐COF) is used to promote directional charge transport and accelerate reaction kinetics. Zinc coordination ( d 10 configuration) induces local symmetry breaking in the framework, giving rise to an internal piezoelectric field that cooperates with a donor–acceptor conjugated network inspired by natural photosynthetic systems. Under combined light and ultrasound excitation, the strain‐induced piezo‐potential facilitates persistent charge separation and suppresses recombination. Ultrafast femtosecond transient absorption spectroscopy demonstrates that Zn incorporation effectively inhibits phonon‐assisted nonradiative decay and prolongs the carrier lifetime to 226.0 ps, which is attributed to the formation of long‐lived shallow trap states and improved exciton delocalization across the π‐conjugated backbone. Consequently, Zn‐Por‐COF achieves a high CO evolution rate of 15.59 mmol g −1  h −1 during piezo‐photocatalytic CO 2 reduction. This work demonstrates that intrinsic piezoelectricity in COF provides an effective strategy to regulate charge dynamics for high‐efficiency light‐driven CO 2 reduction.