Unique spindle-shaped nanoporous anatase TiO(2) mesocrystals with a single-crystal-like structure and tunable sizes were successfully fabricated on a large scale through mesoscale assembly in the tetrabutyl titanate-acetic acid system without any additives under solvothermal conditions. A complex mesoscale assembly process involving slow release of soluble species from metastable solid precursors for the continuous formation of nascent anatase nanocrystals, oriented aggregation of tiny anatase nanocrystals, and entrapment of in situ produced butyl acetate as a porogen was put forward for the formation of the anatase mesocrystals. It was revealed that the acetic acid molecules played multiple key roles during the nonhydrolytic processing of the [001]-oriented, single-crystal-like anatase mesocrystals. The obtained nanoporous anatase mesocrystals exhibited remarkable crystalline-phase stability (i.e., the pure phase of anatase can be retained after being annealed at 900 °C) and improved performance as anode materials for lithium ion batteries, which could be largely attributed to the intrinsic single-crystal-like nature as well as high porosity of the nanoporous mesocrystals.

Uniform anatase TiO2 nanocuboids enclosed by active {100} and {001} facets over a wide size range (60–830 nm in length) with controllable aspect ratios were solvothermally synthesized through hydrolysis of titanium tetraisopropoxide (TTIP) using acetic acid (HAc) as the solvent and the ionic liquid 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([bmim][BF4]) as the capping agent. The size and aspect ratio of the anatase TiO2 nanocuboids can be readily adjusted by changing the composition parameters including the contents of [bmim][BF4], water, and HAc in the quaternary solution system. It was revealed that [bmim][BF4] played an important role in stabilizing both the {100} and {001} facets of the anatase TiO2 nanocuboids. On the one hand, [bmim][BF4] acted as a fluoride source to release F− ions for stabilizing the {001} facets; on the other hand, the [bmim]+ ions acted as effective capping ions to preferentially stabilize the {100} facets. The obtained near‐monodisperse anatase TiO2 nanocuboids exhibited an interesting self‐assembly behavior during deposition. These single‐crystalline anatase nanocuboids showed extremely high crystalline phase stability, retaining the pure phase of anatase as well as the morphology even after being calcined at 900 °C. Moreover, the anatase nanocuboids exhibited considerably enhanced photocatalytic activity owing the wholly exposed active {100} and {001} facets.

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