One‐Dimensional Single‐Crystal Mesoporous TiO2 Supported CuW6O24 Clusters as Photocatalytic Cascade Nanoreactor for Boosting Reduction of CO2 to CH4

Abstract Constructing nanoreactors with multiple active sites in well‐defined crystalline mesoporous frameworks is an effective strategy for tailoring photocatalysts to address the challenging of CO 2 reduction. Herein, one‐dimensional (1‐D) mesoporous single‐crystal TiO 2 nanorod (MS‐TiO 2 ‐NRs, ≈110 nm in length, high surface area of 117 m 2 g −1 , and uniform mesopores of ≈7.0 nm) based nanoreactors are prepared via a droplet interface directed‐assembly strategy under mild condition. By regulating the interfacial energy, the 1‐D mesoporous single‐crystal TiO 2 can be further tuned to polycrystalline fan‐ and flower‐like morphologies with different oxygen vacancies (O v ). The integration of single‐crystal nature and mesopores with exposed oxygen vacancies make the rod‐like TiO 2 nanoreactors exhibit a high‐photocatalytic CO 2 reduction selectivity to CO (95.1%). Furthermore, photocatalytic cascade nanoreactors by in situ incorporation of CuW 6 O 24 (W–Cu) clusters onto MS‐TiO 2 ‐NRs via O v are designed and synthesized, which improved the CO 2 adsorption capacity and achieved two‐step CO 2 –CO–CH 4 photoreduction. The second step CO‐to‐CH 4 reaction induced by W–Cu sites ensures a high generation rate of CH 4 (420.4 µmol g −1 h −1 ), along with an enhanced CH 4 selectivity (≈94.3% electron selectivity). This research provides a platform for the design of mesoporous single‐crystal materials, which potentially extends to a range of functional ceramics and semiconductors for various applications.