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Anodic growth of TiO(2) nanotubes has attracted intensive interests recently. However, the as-prepared TiO(2) nanotubes are usually amorphous and they generally need to be crystallized by sintering above 450 °C. Here, we report on a facile method to crystallize amorphous anodized TiO(2) nanotubes at a low temperature. We find that, simply by immersing them into hot water, the anodized TiO(2) nanotubes can be transformed from amorphous to crystalline state at a temperature as low as 92 °C. Results indicate that the hot water treatment might be a versatile strategy to crystallize amorphous anodized TiO(2) nanotubes at low temperature. Field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, UV-vis spectroscopy, and Brunauer-Emmett-Teller (BET) analysis via N(2) adsorption are used to characterize the resulting samples. In addition, the TiO(2) nanotubes in powder form are taken as photocatalysts to explore their potential applications. Results indicate that the sample after 35 h of hot water treatment shows the highest photoactivity, which is as efficient as the commercial photocatalyst Degussa P25. The photocatalytic testing results demonstrate that the hot water treatment reported in this study can be an alternative approach to the conventional methods.

The volumetric performance of supercapacitors (SCs), besides the gravimetric performance, is attracting an increasing attention due to the fast development of electric vehicles and smart devices. Here, a unique design of symmetric supercapacitor material is reported with a tight face-to-face architecture by applying a high pressure to the delaminated Ti 3 C 2 (d-Ti 3 C 2 ) films. The high pressure makes the d-Ti 3 C 2 films achieve an increased density, high electron conductivity, good wettability, and abundant interconnected mesopore channels to promote ion transport efficiently, that is, more cations can intercalate/deintercalate in the charging-discharging process. As a result, with the increase of the applying pressure, the d-Ti 3 C 2 film pressured at 40 MPa in 1 m Li 2 SO 4 exhibits an ultrahigh capacitance of over 633 F cm −3 , outstanding energy density, and cyclic stability. Especially, the corresponding SC in 1 m 1-ethyl-3-methylimidazolium tetrafluoroborate/acetonitrile organic electrolyte shows a high volumetric energy density of 41 Wh L −1 , which is the highest value reported for the SCs based on MXene materials in organic electrolytes. The outstanding volumetric electrochemical performance and thermal stability of the SCs based on the ultracompact d-Ti 3 C 2 film demonstrate their promising potential as forceful power sources for small electronic devices.

Anatase type nitrogen-fluorine (N-F) codoped TiO(2) nanobelts were prepared by a solvothermal method in which amorphous titania microspheres were used as the precursors. The as-prepared TiO(2) nanobelts are composed of thin narrow nanobelts and it is noted that there are large amount of wormhole-like mesopores on these narrow nanobelts. Photocatalytic activity of the N-F codoped TiO(2) nanobelts was measured by the reaction of photocatalytic degradation of methyl orange. Results indicate that the photocatalytic activity of the N-F codoped TiO(2) nanobelts is higher than that of P25, which is mainly ascribed to wormhole-like mesopores like prison, larger surface area, and enhanced absorption of light due to N-F codoping. Interestingly, it is also found that the photocatalytic activity can be further enhanced when tested in a new testing method because more photons can be captured by the nanobelts to stimulate the formation of the hole-electron pair.

Tremendous efforts have been devoted to exploring high-performance electrocatalysts for fuel cells, but the achievements in catalytic activity and durability are still far from satisfactory for commercialization. Filling metal nanoparticles...

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