Min Li

High-entropy oxides with spinel structure (SHEOs) are promising anode materials for next-generation lithium-ion batteries (LIBs). In this work, electrospun (Mn,Fe,Co,Ni,Zn) SHEO nanofibers produced under different conditions are evaluated as anode materials in LIBs and thoroughly characterised by a combination of analytical techniques. The variation of metal load (19.23 or 38.46 wt% relative to the polymer) in the precursor solution and of calcination conditions (700 °C/0.5 h, or 700 °C/2 h followed by 900 °C/2 h) affects the morphology, microstructure, crystalline phase, and surface composition of the pristine SHEO nanofibers and the resulting electrochemical performance, whereas mechanism of Li⁺ storage does not substantially change. Causes of long-term (≥650 cycles) capacity fading are elucidated via ex situ synchrotron X-ray absorption spectroscopy. The results evidence that the larger amounts of Fe, Co, and Ni cations irreversibly reduced to the metallic form during cycling are responsible for faster capacity fading in nanofibers calcined under milder conditions. The microstructure of the active material plays a key role. Nanofibers composed by larger and better-crystallized grains, where a stable solid/electrolyte interphase forms, exhibit superior long-term stability (453 mAh g⁻¹ after 550 cycles at 0.5 A g⁻¹) and rate-capability (210 mAh g⁻¹ at 2 A g⁻¹).

Lead chalcogenide colloidal quantum dots (CQDs) have the potential to be a new generation of high-performance gas sensing materials for its high chemical activity, facile solution processability and size tunability. However, the high chemical activity of CQDs also leads the CQDs to be easily oxidized, which would reduce the long-term stability of CQDs based gas sensors. Here we try to introduce halogen ligands in the synthesis of PbS CQDs by using lead halide as precursor. These halogen ligands play a passivate role and are beneficial in improving the long-term stability of PbS CQDs based gas sensors. Results show that although the PbS CQDs synthesized using lead halide as precursor exhibit relatively low sensor response than that synthesized using traditional lead oxide as precursor, it exhibit faster response and recovery times. More importantly, the sensors employing halogen passivated PbS CQDs exhibit superior long-term stability, in which more than 80% of their original NO ₂ -sensing performance are still presented after 30 days. It could be attributed to the surface halogen derived from the lead precursor, which prevent CQDs from reacting with the atmosphere and thus maintain the oxidative stability of CQDs. This research will pave the way for improving the long-term stability of lead chalcogenide CQDs based gas sensors.

In this work we report a strategy for generating porosity in hybrid metal halide materials using molecular cages that serve as both structure‐directing agents and counter‐cations. Reaction of the [2.2.2] cryptand (DHS) linker with Pb^II in acidic media gave rise to the first porous and water‐stable 2D metal halide semiconductor (DHS)₂Pb₅Br₁₄. The corresponding material is stable in water for a year, while gas and vapor‐sorption studies revealed that it can selectively and reversibly adsorb H₂O and D₂O at room temperature (RT). Solid‐state NMR measurements and DFT calculations verified the incorporation of H₂O and D₂O in the organic linker cavities and shed light on their molecular configuration. In addition to porosity, the material exhibits broad light emission centered at 617 nm with a full width at half‐maximum (FWHM) of 284 nm (0.96 eV). The recorded water stability is unparalleled for hybrid metal halide and perovskite materials, while the generation of porosity opens new pathways towards unexplored applications (e.g. solid‐state batteries) for this class of hybrid semiconductors.

Nitrogen dioxide is one origin of air pollution from fossil fuels with the potential to cause great harm to human health in low concentrations. Therefore, low-cost, low-power-consumption sensors for low-concentration NO₂ detection are essential. Herein, heterojunction by SnO₂ quantum wires, a traditional metal oxide NO₂ sensing material, and Ti₃C₂T_x MXene, a novel type of 2D layered material, was synthesized using a simple solvothermal method for enhancing gas-sensing performance and reducing operating temperature. The operating temperature was reduced to 80 °C, with a best performance of 27.8 and a fast response and recovery time (11 s and 23 s, respectively). The SnO₂ and Ti₃C₂T_x MXene composite exhibits high speed and low detection limit due to the construction of the heterojunction with high conductive Ti₃C₂T_x MXene. The selectivity and stability of gas sensors are carried out. This could enable the realization of fast response, high-sensitivity, and selective NO₂ sensing under low operating temperatures.