Cerium ions (Ce(3+)) can be selectively doped into the TiO2(B) core of TiO2(B)/anatase core-shell nanofibers by means of a simple one-pot hydrothermal treatment of a starting material of hydrogen trititanate (H2Ti3O7) nanofibers. These Ce(3+) ions (≈0.202 nm) are located on the (110) lattice planes of the TiO2(B) core in tunnels (width≈0.297 nm). The introduction of Ce(3+) ions reduces the defects of the TiO2(B) core by inhibiting the faster growth of (110) lattice planes. More importantly, the redox potential of the Ce(3+)/Ce(4+) couple (E°(Ce(3+)/Ce(4+))=1.715 V versus the normal hydrogen electrode) is more negative than the valence band of TiO2(B). Therefore, once the Ce(3+)-doped nanofibers are irradiated by UV light, the doped Ce(3+) ions--in close vicinity to the interface between the TiO2(B) core and anatase nanoshell--can efficiently trap the photogenerated holes. This facilitates the migration of holes from the anatase shell and leaves more photogenerated electrons in the anatase nanoshell, which results in a highly efficient separation of photogenerated charges in the anatase nanoshell. Hence, this enhanced charge-separation mechanism accelerates dye degradation and alcohol oxidation processes. The one-pot treatment doping strategy is also used to selectively dope other metal ions with variable oxidation states such as Co(2+/3+) and Cu(+/2+) ions. The doping substantially improves the photocatalytic activity of the mixed-phase nanofibers. In contrast, the doping of ions with an invariable oxidation state, such as Zn(2+), Ca(2+), or Mg(2+), does not enhance the photoactivity of the mixed-phase nanofibers as the ions could not trap the photogenerated holes.

A simple additive-free approach is developed to synthesize uniform manganese monoxide (MnO) one-dimensional nanorods, in which only manganese acetate and ethanol were used as reactants. The as-synthesized MnO nanorods were characterized in detail by X-ray diffraction, scanning and transmission electron microscopy (TEM) including high-resolution TEM and selected-area electron diffraction, Fourier transform infrared spectrum, and nitrogen adsorption isotherm measurements. The results indicate that the as-synthesized MnO nanorods present a mesoporous characteristic with large specific surface area (153 m2 g−1), indicating promising applications in catalysis, energy storage, and biomedical image. On the basis of experimental results, the formation mechanism of MnO one-dimensional nanorods in the absence of polymer additives was also discussed.

No abstract

The nitrides Ca2Si5N8:0.5%Eu2+, x%Tm3+(x = 0, 0.5, 1, 2, 4) (CSN:0.5E, xT) phosphors were prepared via the high temperature solid‐sintering method using CaH2 as calcium source. These phosphors exhibited strong orange long‐lasting phosphorescence (LLP) after turning off the activating light. Besides, the CSN:0.5E, 1T phosphor with an afterglow time of more than 200 min (0.32 mcd/m2). Furthermore, the temperature‐dependent emission spectra of CSN:0.5E, 1T were investigated from temperature 80–500 K and an anti‐quenching phenomenon that the emission intensities increased then decreased under excitation at increased temperature was found. Ultimate, the proposed mechanism on temperature dependence of luminescence was analyzed. This study provides a new perspective for the impact of temperature‐dependent problem as a consequence of heating processes in luminescent materials.

The newly functional polymeric semiconductor materials, mesoporous graphitic carbon nitride (g-C 3 N 4 ), have been synthesized by using a general and efficient sol-gel synthetic approach. By means of transmission electron microscopy (TEM), we accomplished a systematic analysis on the morphology changes and the final formation of the mesoporous g-C 3 N 4 product during the whole synthesis process.Our results indicate that the sol-gel synthetic method is a simple, efficient and viable technique to the large-scale production of mesoporous polymeric materials. This proposed technique also allows controlled development and tailored design of the pore structures, which is of crucial importance for the application of mesoporous polymeric g-C 3 N 4 . In order to effectively improve the photocatalytic activity of the g-C 3 N 4 , the uniform size of the AgBr nanoparticles (NPs) were successfully loaded into the holes of the carbon nitride by a simple adsorption-deposition method, which exhibits excellent visible-light-driven photocatalytic activity for degradation of Methyl Orange dye (MO).