Highly Strained Bi-MOF on Bismuth Oxyhalide Support with Tailored Intermediate Adsorption/Desorption Capability for Robust CO 2 Photoreduction.

Herein, using as-designed surface-mounted Bismuth-based metal-organic framework (Bi-MOF) on two-dimensional BiOBr support, as an operable platform for site-specific strain engineering to tailor the intermediate adsorption/desorption capability in CO 2 photocatalytic conversion is proposed. Giant compressive strain up to 7.85 % is successfully induced on the surface-mounted Bi-MOF revealed by HRTEM images and geometric phase analysis as well as in situ Raman characterization, which largely downshifts the p band center of Bi nodes and intensifies their unsaturated state. In-depth explorations are put onto p-p (Bi 6p and CO 2 /CO 2p) orbital hybridization. Taking the adsorption process as an example, the 1π and 7σ frontier molecule orbitals of CO 2 2p for both the strain-free and strained models shift downwards the Fermi level, indicative of fast adsorption of CO 2 . Meanwhile, strain engineering further induces new non-degenerate orbital overlapping near 1π and intensified overlapping of 7σ orbitals, stimulating the fast activation of absorbed CO 2 molecules.