We report on the design of ultraviolet (UV) emitting persistent (PersL) materials. Understanding the luminescence mechanism of Bi3+ ions, the occupation rules of sites, the density functional theory (DFT) calculations and an empirical energy level scheme guided us to select the most appropriate emitters, host and traps. Finally, the NaLuGeO4:Bi3+,Eu3+ phosphor was successfully designed. The experimental results indicated that the NaLuGeO4:Bi3+,Eu3+ material is indeed able to emit excellent UV PersL, which can be recorded for more than 63 h. This exciting result is sufficiently encouraging for the initiation of a more thorough investigation. Accordingly, the excitation temperature-dependent and fading thermoluminescence experiments were conducted, and the trap properties were deeply studied by the initial rising method. The results reveal the PersL mechanism and the significant role of Eu3+ codopants as foreign traps. On the basis of this work, the UV PersL of the as-designed NaLuGeO4:Bi3+,Eu3+ material is certainly promising for some potential multifunctional applications, and the design concepts of this work are indeed effective and feasible for the design of PersL materials.

In this study, polyurethane/polyvinyl alcohol hydrogel was prepared by chemical cross-linking. Silver particles were further composited in the hydrogel via an in situ synthesis technique. The chemical structure and porous morphology were determined by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and field-emission scanning electron microscopy. The swelling abilities, mechanical behaviors, tribological properties, biocompatibilities and antibacterial properties of the hydrogels were investigated. The results suggest that the incorporation of silver particles in polyurethane/polyvinyl alcohol hydrogels could enhance the Young's modulus, tensile strength and elongation, as well as reduce the friction coefficient, while maintaining hydrogels with a moderate water absorption ability and good biocompatibility. Moreover, the addition of silver particles could endow the polyurethane/polyvinyl alcohol hydrogel with prominent antibacterial performance, suggesting that polyurethane/polyvinyl alcohol/silver composite hydrogels could be applied as dressings for wound healing.

Phosphors are efficient luminescent materials that are being extensively used in lighting and displays in today's world. However, the serious emission loss at high temperatures due to thermal quenching effects is still one of the most significant challenges that limit the application of phosphors. Herein, we report a unique thermal sensitizing effect of the Na2CaGe6O14:Pr3+ phosphor, in which the red emission of Pr3+ is significantly enhanced with the increase in temperature, even upto 250 °C. Moreover, the emission of the phosphor still keeps increasing over time at high temperatures. This thermally induced emission increase originates from the generation of more defect levels and more efficient energy transfer from the defects to Pr3+ at higher temperatures. This significant discovery may enlighten a new strategy to minimize or even completely eliminate the serious thermally induced emission loss of the phosphors.

In this work, we report a simple self-assembly way to prepare ceria/graphene oxide (CeO2/GO) composite films on silicon (Si) substrates, which exhibit significant enhancement on tribological performances compared with Si substrates and GO films. Specifically, the friction coefficient is reduced drastically to the one-third of that of Si substrates. What’s more, the antiwear lifetime is markedly prolonged to ∼8 h under a high applied load of 2 N, which is over seven times longer than that of GO films. It is expected that the CeO2/GO composite films may find wide applications in nano/microelectromechanical systems as high-performance solid lubricating films, due to their facile and low cost preparation, nano-scale thickness, lower friction coefficient and desired antiwear lifetime.

•Bi modified TiO2 nanofibers were prepared by a two step electrospinning.•Significantly enhanced visible light photocatalytic activity was achieved.•The mechanism of photodegradation under visible light was investigated.Uniform Bi nanoparticle modified TiO2 porous nanofibers were prepared via the processes of emulsion electrospinning and the subsequent calcination. The morphology, crystal structure, optical and photocurrent responses, as well as the photocatalytic performance of the obtained photocatalysts were characterized and investigated in detail. The results suggest that the modified TiO2 porous nanofibers show significantly enhanced visible light photocatalytic activity, as Bi nanoparticles would largely extend the visible light absorption of TiO2 because of its surface plasmon resonance. The co-existence of the semiconductor behavior of Bi nanoparticles could further prevent the recombination of electrons in the conduction band with holes. Overall, this work provides new insights into the fabrication of TiO2 based composites as high performance photocatalysts, facilitating their application in the environmental protection issues.

Nanocomposites consisting of zirconia (ZrO2) nanoparticles and reduced graphene oxide (rGO) nanosheets were successfully fabricated by a one-pot hydrothermal method. By regulating the proportion of the precursors of the GO colloidal suspension and zirconium oxychloride (ZrOCl2) solution, ZrO2 nanoparticles with a diameter of about 5 nm were uniformly anchored onto the rGO nanosheets. The combination mechanism of ZrO2 nanoparticles fully bonded onto rGO nanosheets is the formation of the monodentate or bidentate composites between the oxygen-containing groups of GO and Zr(IV) complex ions from hydrolysis of the ZrOCl2 solution. The dispersibility and tribological properties of the prepared composites were investigated as novel lubricant additives in paraffin oil. The results suggested that the oil with a small amount of nanocomposite (0.06 wt%) exhibits good dispersibility, excellent friction-reduction and anti-wear properties as well as a high load-bearing capacity caused by the synergistic effect of the rGO nanosheets and ZrO2 nanoparticles.

Graphene decorated with well-dispersed cubic fluorite ceria (CeO2) nanoparticles was prepared through a simple hydrothermal method. The as-prepared CeO2/graphene composites (COGNCs) were further used as lubricant additives in the base oil of liquid paraffin to investigate their tribological properties by the Optimol SRV-1 oscillating reciprocating friction and wear tests in air (relative humidity, 17%). The results indicated that the introduction of a small amount of COGNCs into the base oil could reduce friction and wear drastically under a high load condition, which was better than the testing results of graphene or CeO2 nanoparticles. Specifically, when 0.06 wt% COGNCs was added into the base oil, the average friction coefficient could be reduced from 0.21 to 0.10, and the wear rate could be decreased to 1.5% of that of base oil. The excellent tribological properties of COGNCs can be explained by the synergistic friction reduction and antiwear effects of graphene and CeO2 nanoparticles.

We report on the design of ultraviolet (UV) emitting persistent (PersL) materials. Understanding the luminescence mechanism of Bi3+ ions, the occupation rules of sites, the density functional theory (DFT) calculations and an empirical energy level scheme guided us to select the most appropriate emitters, host and traps. Finally, the NaLuGeO4:Bi3+,Eu3+ phosphor was successfully designed. The experimental results indicated that the NaLuGeO4:Bi3+,Eu3+ material is indeed able to emit excellent UV PersL, which can be recorded for more than 63 h. This exciting result is sufficiently encouraging for the initiation of a more thorough investigation. Accordingly, the excitation temperature-dependent and fading thermoluminescence experiments were conducted, and the trap properties were deeply studied by the initial rising method. The results reveal the PersL mechanism and the significant role of Eu3+ codopants as foreign traps. On the basis of this work, the UV PersL of the as-designed NaLuGeO4:Bi3+,Eu3+ material is certainly promising for some potential multifunctional applications, and the design concepts of this work are indeed effective and feasible for the design of PersL materials.