Two host-guest Ti-oxide clusters, Ti14(NH4)2 and Ti14Cs2, were synthesized and thoroughly characterized. They possess a rarely seen biloculate structure that encapsulates two NH4 + and Cs+ guests, respectively. Interestingly, alkali metal cations can exchange places with NH4 +. The ability of the host to capture the guest cations follows the order Cs+ > NH4 + > Rb+ > K+. The guests heavily influence the physiochemical properties and photocatalytic activities of the complexes. Ti14Cs2 exhibits a redshifted visible-light absorption edge, increased charge-separation properties, and enhanced interfacial charge-transfer ability compared to Ti14(NH4)2. It also demonstrates excellent performance in photocatalytic CO2/epoxide cycloaddition reactions regarding the reaction rate, scalability, sunlight usage, catalyst recyclability, and stability. This study presents a novel Ti-oxide-based cage cluster with exchangeable guests and provides insights for enhancing the solar harvesting applications of Ti-oxide cages.
This journal is © The Royal Society of Chemistry.