Enhancing the photocatalytic performance of a rutile unit featuring a titanium-oxide cluster by Pb²⁺ doping

Titanium-oxide clusters (TOCs) are well-defined molecular models for TiO₂ materials and provide the opportunity to study the structure-activity relationships of TiO₂. Here, we report a new Pb-doped TOC, Ti12Pb2, which resembles a two-layer decker of the {TiTi₆} structural units of rutile TiO₂ with two Ti⁴⁺ ions replaced by two Pb²⁺ ions. Its electronic structure, photoresponse, and photocatalytic performances were investigated and compared with those of the Ti14 cluster, which is isostructural to Ti12Pb2. Our results indicate that Pb²⁺ does not affect the electronic structure, but it greatly enhances the photocatalytic activity by improving the charge-separation and interfacial charge-transfer properties of the TOC. The successful synthesis of Ti12Pb2 highlights the roles of closed-shell heterometal ions in the construction of new TOCs. Our mechanism may be an inspiration for understanding the structure-activity relationships of closed-shell heterometal-doped TiO₂.