Seed‐Mediated Growth of a High‐Nuclearity Titanium‐Oxide Cluster with Enhanced Photocatalytic Activities in CO₂/Epoxide Cycloaddition

Abstract

A high‐nuclearity titanium‐oxide cluster (TOC), Ti31O52(OiPr)4Bz24 (denoted as Ti31; Bz = PhCO2), was synthesized via a seed‐mediated synthesis method during the solvothermal reaction of the super‐Keggin cluster Ti17O24(OiPr)20 (denoted as Ti17) and Ti(OiPr)4. Single‐crystal X‐ray diffraction analyses indicate that Ti17 acts as a template for the addition of two Ti7O6 rings to form Ti31. The optical absorption edge of Ti31 slightly shifts to 446 nm, relative to the 419 nm absorption edge of Ti17. Ti31 has much better visible−light response and charge−separation properties than Ti17, as confirmed by electrochemical impedance, photoluminescence spectroscopy, and transient photocurrent response. Ti31 also shows much better activity and stability than Ti17 in the solar synthesis of cyclocarbonate through CO2/epoxide cycloaddition. This study not only provides a high‐nuclearity member of the TOC family, but also suggests a potential method to enhance the photocatalytic activity of the known TOCs for more efficient solar energy harvesting.