Functionalization of zeolite-encapsulated Cu clusters as visible-light photoactive sub-nanomaterials.

The unique structural properties of zeolites make them ideal environments for encapsulating subnanometric metal clusters on their microporous channels and cavities, showing an enhanced catalytic performance. As a first step towards the functionalization of these clusters as photocatalysts as well, this work addresses the optical properties of zeolite-encapsulated Cu-TiO nanoparticles as well as their application in the photo-induced activation of CO by sunlight. Model density functional theory (DFT) calculations indicate the stability of the Cu cluster adsorbed on the TiO nanoparticles filling the pores of a model zeolite structure. Second, it is shown that while TiO nanoparticles absorb in the UV, the photo-absorption spectrum of the Cu-TiO nanoparticle composite is peaked at the visible region, where the sun has its maximum energy input, also allowing for the photo-induced activation of CO adsorbed onto the Cu cluster.