Tailored Persistent Radical‐containing Heterotrimetal‐Organic Framework for Boosting Efficiency of Visible/NIR Light‐driven Photocatalytic CO₂ Reduction

Abstract Promoting light absorption range of photocatalysts is of great significance to improve solar light‐driven photocatalytic CO₂ reduction efficiency. Herein, a new viologen‐based multicomponent heterotrimetallic metal–organic framework (MOF) [Cu₃Th₆(µ₃‐O)₄(µ₃‐OH)₄(cpb)₁₂][Fe^III(CN)₆]₆ (IHEP‐14) with an unprecedented (6, 18)‐connected she‐d topology is presented. Upon UV irradiation, this MOF undergoes ligand and iron photoreduction, and a single‐crystal‐to‐single‐crystal transformation to generate persistent radical‐containing MOF [Cu₃Th₆(µ₃‐O)₄(µ₃‐OH)₄(cpb^•)₁₂][Fe^II(CN)₆]₆ (IHEP‐15). This radical‐containing MOF shows excellent stability without fading after at least 2 months in air. Besides extending the photoabsorption to a wider wavelength range covering from 200 to 2,500 nm, the generation of persistent radical in IHEP‐15 also largely enhances its CO₂ adsorption capacity by a factor of three due to the strong affinity between π orbital of the radical and the π system of CO₂. These attributes endow IHEP‐15 with excellent visible/NIR light‐driven CO₂ photoreduction activity, with CO production rates under visible and NIR irradiation of 570.3 and 209.3 µmol h⁻¹ g⁻¹, respectively. Notably, the latter is a record high for NIR‐induced CO production among all MOFs reported so far.