Isomerism in Titanium‐Oxo Clusters: Molecular Anatase Model with Atomic Structure and Improved Photocatalytic Activity

Abstract Phase isomerism is a common and important phenomenon in inorganic materials, but the molecular isomerism of their nanocluster models is still rare. In this work, we report the first pair of isomeric titanium‐oxo clusters. Through combining pentagonal {Ti(Ti 5 )} building units in corner‐sharing or edge‐sharing forms, the two obtained Ti 20 ‐oxo clusters take vertical and horizontal core configurations, respectively, which are both functionalized by the same organic ligands. More interestingly, the vertical type Ti 20 ‐oxo core contains an identical {Ti 8 O 14 } moiety as anatase, making it the first molecular model of anatase TiO 2 . As a result, the vertical type cluster exhibits better photocatalytic H 2 evolution activity, higher photocurrent response and faster charge transfer to external acceptors than its horizontal isomer. Thus, this work provides a cluster isomer method to understand the structure–property relationship of import titanium oxide materials.