A Blinking Mesoporous TiO2‐x Composed of Nanosized Anatase with Unusually Long‐Lived Trapped Charge Carriers

: A novel mesoporous TiO2-x material that is comprised of small, crystalline, vacancy-rich anatase nanoparticles that show unique optical, thermal and electronic properties is synthesized using polymer-derived mesoporous carbon (PDMC) as a template. The PDMC pores serve as physical barriers during the condensation and pyrolysis of a titania precursor, preventing the titania nanoparticles from growing beyond 10 nm in size. Unlike most titania nanomaterials, the particles remain in anatase phase and undergo no transition to rutile phase, and also become catalytically-active reduced TiO2-x, during pyrolysis. When exposed to a slow electron beam, the nanoparticles exhibit an unprecedented charge/discharge behavior, continuously lighting up and fading away for an average period of ca. 15 s, for an extended period of time. The nanoparticles also show a 50 nm-red-shift in their UV-vis absorption and long-lived charge carriers (electrons and holes) at room temperature in the dark, even long after UV irradiation. The potential of the new anatase nanoparticles as photocatalysts is demonstrated using CO2 reduction, in which they show a good activity.