Solid-solution MAX phase TiVAlC assisted with impurity for enhancing hydrogen storage performance of magnesium hydride.

Although MXene catalysts etched from precursor MAX have greatly improved the hydrogen storage performance of magnesium hydride (MgH2), the use of dangerous and polluting etchers (such as hydrofluoric acid) and the direct removal of potentially catalytically active A-layer substances (such as Al) present certain limitations. Here, solid-solution MAX phase TiVAlC catalyst without etching treatment has been directly introduced into MgH2 system to improve the hydrogen storage performance. The optimal MgH2-10 wt% TiVAlC can release about 6.00 wt% hydrogen at 300 °C within 378 s and absorb about 4.82 wt% hydrogen at 175 °C within 900 s. After 50 isothermal hydrogen ab/desorption cycles, the excellent cyclic stability and capacity retention (6.4 wt%, 99.6%) can be found for MgH2-10 wt% TiVAlC. The superb catalytic activity of TiVAlC catalyst can be explained by abundant electron transfer at external interfaces with MgH2/Mg, which can be further enhanced by impurity phase Ti3AlC2 due to strong H affinity brought from abundant electron transfer at internal interfaces (Ti3AlC2/TiVAlC). The influence of impurity phase which is common in MAX phase on the overall activity of catalysts has been firstly studied here, providing a unique method for designing composite catalyst to improve hydrogen storage performance of MgH2.

Er3+ Sensitized 1530†nm to 1180†nm Second Near-Infrared Window Upconversion Nanocrystals for In†Vivo Biosensing.

Fluorescent bioimaging in the second near-infrared window (NIR-II) can probe deep tissue with minimum auto-fluorescence and tissue scattering. However, current NIR-II fluorophore-related biodetection in vivo is only focused on direct disease lesion or organ bioimaging, it is still a challenge to realize NIR-II real-time dynamic biosensing. A new type of Er3+ sensitized upconversion nanoparticles are presented with both excitation (1530 nm) and emission (1180 nm) located in the NIR-II window for in vivo biosensing. The microneedle patch sensor for in vivo inflammation dynamic detection is developed based on the ratiometric fluorescence by combining the effective NIR-II upconversion emission and H2 O2 sensing organic probes under the Fenton catalysis of Fe2+ . Owing to the large anti-Stokes shifting, low auto-fluorescence, and tissue scattering of the NIR-II upconversion luminescence, inflammation can be dynamically evaluated in vivo at very high resolution (200×200 µm).

From ScOOH to Sc2 O3 : Phase Control, Luminescent Properties, and Applications.

In the controlled synthesis of ScOOH nanomaterials, the surfactant molecule Na3 Cit not only helps to manipulate the crystallographic structures, but also to initiate the transfer from α-ScOOH to γ-ScOOH. Further annealing of ScOOH generates cubic Sc2 O3 with morphologies inherited from respective origins. When doped with lanthanide ions, both ScOOH and Sc2 O3 can be utilized for high-temperature probing and light-emitting-diode lighting.

Bi2MoO6 nanobelts for crystal facet-enhanced photocatalysis.

γ-Bi2MoO6 single-crystal nanobelts with dominant {010} facets exhibit facet-enhanced photocatalytic property for the photodegradation of dye pollutants under visible light irradiation. The charge carriers are more efficiently separated on the low-index facets due to the exposure of more photoactive sites to the reacting substrates.

Rare Earth Ion-Doped Upconversion Nanocrystals: Synthesis and Surface Modification.

The unique luminescent properties exhibited by rare earth ion-doped upconversion nanocrystals (UCNPs), such as long lifetime, narrow emission line, high color purity, and high resistance to photobleaching, have made them widely used in many areas, including but not limited to high-resolution displays, new-generation information technology, optical communication, bioimaging, and therapy. However, the inherent upconversion luminescent properties of UCNPs are influenced by various parameters, including the size, shape, crystal structure, and chemical composition of the UCNPs, and even the chosen synthesis process and the surfactant molecules used. This review will provide a complete summary on the synthesis methods and the surface modification strategies of UCNPs reported so far. Firstly, we summarize the synthesis methodologies developed in the past decades, such as thermal decomposition, thermal coprecipitation, hydro/solvothermal, sol-gel, combustion, and microwave synthesis. In the second part, five main streams of surface modification strategies for converting hydrophobic UCNPs into hydrophilic ones are elaborated. Finally, we consider the likely directions of the future development and challenges of the synthesis and surface modification, such as the large-scale production and actual applications, stability, and so on, of the UCNPs.