A cryptand-like Ti-coordination compound with visible-light photocatalytic activity in CO2 storage

Abstract

A cryptand-like Ti-coordination compound, namely Ti₁₂Cs, comprising two Ti₆-salicylate cages and hosting two Cs⁺ ions, was synthesized by the solvothermal method. It exhibits strong visible-light absorption with an absorption band edge of 652 nm, attributed to the electron transition from salicylate ligands to Ti ions. Electrochemical impedance, visible-light transient photocurrent response, and photoluminescence spectra confirm that Ti₁₂Cs has excellent visible-light response and charge-separation properties. Ti₁₂Cs can be used as a heterogeneous and recyclable photocatalyst for CO₂/epoxide cycloaddition, with high utilization efficiency of visible-light under mild conditions. The mechanism investigation points to a synergistic effect of photocatalysis and Lewis acid catalysis.