Conformationally Adaptive Exfoliation of Porphyrin MOFs Liberates Interlayer Confinement for Enhanced Photocatalytic CO 2 Reduction

ABSTRACT The use of two‐dimensional (2D) photocatalysts for CO 2 reduction remains severely constrained by buried active sites and inefficient charge transfer, primarily due to the underutilization of interlayer‐confined spaces in bulk materials. Herein, we present a conformationally adaptive exfoliation strategy for a porphyrin metal–organic framework ( IHEP‐88 ) that directly releases interlayer confinement without requiring complex functionalization. Solvent‐responsive expansion of the interlayer spacing, followed by mild mechanical exfoliation, yields ultrathin nanosheets with substantially increased accessible surface area and a 2.2‐fold enhancement in CO 2 uptake, reaching 3.1 mmol·g −1 . The subsequent incorporation of cobalt centers into the porphyrin units generates redox‐active catalytic sites, wherein reversible Co 2+ /Co 3+ valence change lowers the energy barrier for CO 2 reduction. As a result, the exfoliated cobalt‐containing nanosheets ( IHEP‐88(Co)‐NS ) exhibit an exceptional CO evolution rate of 790 µmol·g −1 ·h −1 , which represents an 18‐fold enhancement relative to the bulk materials and outperforms the vast majority of non‐precious‐metal porphyrin MOFs reported thus far. The reduction mechanism of CO 2 was elucidated through a combination of in situ DRIFTS, XPS, EXAFS analysis, and theoretical calculations. Collectively, these findings establish that the liberation of interlayer confinement through adaptive exfoliation offers a powerful and generalizable pathway toward high‐performance photocatalysts for solar‐fuel conversion.