Tailored Persistent Radical-containing Heterotrimetal-Organic Framework for Boosting Efficiency of Visible/NIR Light-driven Photocatalytic CO_2 Reduction

摘要

Promoting light absorption range of photocatalysts is of great significanceto improve solar light-driven photocatalytic CO_2 reduction efficiency. Herein,a new viologen-based multicomponent heterotrimetallic metal–organicframework (MOF) [Cu_3Th_6(μ_3-O)_4(μ_3-OH)_4(cpb)_(12)][Fe~(Ⅲ)(CN)_6]_6 (IHEP-14)with an unprecedented (6, 18)-connected she-d topology is presented. UponUV irradiation, this MOF undergoes ligand and iron photoreduction, and asingle-crystal-to-single-crystal transformation to generate persistent radicalcontainingMOF [Cu_3Th_6(μ_3-O)_4(μ_3-OH)_4(cpb~?)_(12)][Fe~(Ⅱ)(CN)_6]_6 (IHEP-15). Thisradical-containing MOF shows excellent stability without fading after at least2 months in air. Besides extending the photoabsorption to a wider wavelengthrange covering from 200 to 2,500 nm, the generation of persistent radical inIHEP-15 also largely enhances its CO_2 adsorption capacity by a factor of threedue to the strong affinity between π orbital of the radical and the π system ofCO_2. These attributes endow IHEP-15 with excellent visible/NIR light-drivenCO_2 photoreduction activity, with CO production rates under visible and NIRirradiation of 570.3 and 209.3 μmol h~(?1) g~(?1), respectively. Notably, the latter is arecord high for NIR-induced CO production among all MOFs reported so far.