Dynamic Responsive Cd-MOF upon the Stimulation of Temperature and Solvent for Photocatalytic CO2RR

Precise construction of stimuli-responsive MOF (SRMOF) materials with excellent catalytic properties is a daunting challenge. Herein, two flexible ligands 4,4′,4″-(nitrilotris(methylene))tribenzoic acid (H3L) and 1,4-bis((1H-imidazol-1-yl)methyl)benzene (BMB) have been used to construct a Cd-MOF (AQNU-5, AQNU named Anqing Normal University) containing three-dimensional pores and rod SBUs. Due to the flexible ligand-induced dynamic framework, AQNU-5 exhibits structural flexibility with stimuli-responsive properties in photocatalytic CO2 reduction, which depends on both temperature and solvent. The results showed that the CO2-to-CO reduction rate reached an optimum of 56.2 μmol g–1 h–1 at 150 °C without the addition of any photosensitizer. Interestingly, this dynamic response is reversible, with the skeleton remaining unchanged from the parent structure before and after the catalytic reaction. The strategy of using flexible ligands in this work may provide a unique opportunity to obtain novel crystal framework materials with desirable properties.