Photodegradation Activity of Poly(ethylene oxide-b-ε-caprolactone)-Templated Mesoporous TiO2 Coated with Au and Pt.

Mesoporous TiO2 films are synthesized through evaporation-induced self-assembly using poly(ethylene oxide-b-ε-caprolactone) diblock copolymers as a soft-template. Using small-angle X-ray scattering and scanning electron microscopy, we investigate the effect of the TiO2/PEO-b-PCL ratio on the resulting nanoarchitectonic structure. After sputter-coating Au and Pt layers, these Au/TiO2 and Pt/TiO2 nanocomposite films display drastically enhanced photodegradation of rhodamine 6G under ultraviolet irradiation, due to the metal films inhibiting the rapid recombination of photogenerated charge carriers.

Nanoarchitectured peroxidase-mimetic nanozymes: mesoporous nanocrystalline α- or γ-iron oxide?

Nanozymes (nanoparticles with enzyme-like properties) have attracted considerable attention in recent years owing to their intrinsic enzyme-like properties and broad application in the fields of ELISA based immunoassay and biosensing. Herein, we systematically investigate the influence of crystal phases (γ-Fe2O3 and α-Fe2O3) of mesoporous iron oxide (IO) on their peroxidase mimetic activity. In addition, we have also demonstrated the applicability of these mesoporous IOs as nanozymes for detecting the glucose biomarker with a limit of detection (LOD) of 0.9 µM. Mesoporous γ-Fe2O3 shows high nanozyme activities (and magnetism) toward the catalytic oxidation of chromogenic substances, such as 3,3',5,5'-tetramethylbenzidine (TMB) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)-ABTS, as well as for the colourimetric detection of glucose, compared to that of α-Fe2O3. We believe that this in-depth study of crystal structure based nanozyme activity will guide designing highly effective nanozymes based on iron oxide nanostructures for chemical sensing, biosensing and environmental remediation.

Synthesis of Mesoporous TiO2-B Nanobelts with Highly Crystalized Walls toward Efficient H2 Evolution.

Mesoporous TiO2 is attracting increasing interest due to properties suiting a broad range of photocatalytic applications. Here we report the facile synthesis of mesoporous crystalline TiO2-B nanobelts possessing a surface area as high as 80.9 m2 g-1 and uniformly-sized pores of 6-8 nm. Firstly, P25 powders are dissolved in NaOH solution under hydrothermal conditions, forming sodium titanate (Na2Ti3O7) intermediate precursor phase. Then, H2Ti3O7 is successfully obtained by ion exchange through acid washing from Na2Ti3O7 via an alkaline hydrothermal treatment. After calcination at 450 °C, the H2Ti3O7 is converted to a TiO2-B phase. At 600 °C, another anatase phase coexists with TiO2-B, which completely converts into anatase when annealed at 750 °C. Mesoporous TiO2-B nanobelts obtained after annealing at 450 °C are uniform with up to a few micrometers in length, 50-120 nm in width, and 5-15 nm in thickness. The resulting mesoporous TiO2-B nanobelts exhibit efficient H2 evolution capability, which is almost three times that of anatase TiO2 nanobelts.