Search

The commercial application of lithium–sulfur batteries is severely hampered by polysulfide shuttle effects. We predicted a novel niobium phosphide–niobium carbide heterostructure as a productive polysulfide adsorbent and catalytic material for Li–S batteries and successfully synthesized a NbP–NbC heterostructure, which was evenly dispersed on porous carbon (NbP–NbC/C). Density functional theory calculations indicated that the heterostructure between NbP and NbC regulated the interfacial electric field, promoting electron transfer and decreasing the reaction energy barrier to accelerate the transformation of polysulfides. The heterostructure induced interfacial charge redistribution, transferring more electrons to the surface and facilitating rapid lithium-ion transport while accelerating polysulfide transfer. This provided moderate polysulfide absorbability and further enhanced the intrinsic catalytic activity of NbP–NbC/C. Furthermore, in situ characterization and catalytic experiments were conducted to verify that the NbP–NbC/C heterostructure exhibited excellent cycling stability and electrochemical and catalytic properties. Accordingly, the NbP–NbC/C@S cathode showed a high reversible capacity (1367.9 mA h g−1 at 0.2C) and stable long-life span with 250 cycles (≈89% retention at 0.2C). Importantly, the thick sulfur cathode (sulfur loading: 8.2 mg cm−2) presented a large area capacity of 6.5 mA h cm−2, and the NbP–NbC@S‖Li flexible Li–S pouch cell demonstrated an excellent initial energy density value of 451 W h kg−1. [ABSTRACT FROM AUTHOR]

Developing highly effective antibacterial films to promote wound healing remains a huge challenge. Herein, homogeneous and self-standing CDs-PVA composite films (PVA3, PVA5 and PVA8) were constructed by doping various mass ratios (3, 5 and 8 wt%) of carbon dots (CDs) into polyvinyl alcohol (PVA), which had no cracks or macroscopic defects. Moreover, the robust mechanical strength and flexibility enabled them to be cut into diverse patterns as required, which provided unique advantages for being employed as a wound dressing. PVA5 and PVA8 were powerful broad-spectrum bactericides and they could kill both Gram-negative bacteria and Gram-positive bacteria like Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with the antibacterial efficacy over 90.0%. More significantly, the biocompatible films could be readily processed into a "band-aid" type dressing for wound healing. The PVA5 band-aids were just pasted on the wounds for two days and then removed, and the wounds were completely closed after fourteen days. Neither introducing any metals or antibiotics, nor with the help of any external activation, these kinds of CD-based films have the strengths of low cost, being easy to use, excellent biocompatibility and outstanding antibacterial performance, and are desirable wound dressings for various skin injuries. [ABSTRACT FROM AUTHOR]

Even with advances in diverse antibiotics, bacterial infectious diseases with high mortality and morbidity still seriously endanger human health, which spurs the development of alternative antiseptic and therapeutic strategies for combatting bacteria. Antimicrobial photodynamic inactivation (aPDI) has emerged as an effective treatment protocol for different types of infection. Moreover, the risk from Gram-positive organisms cannot be overlooked. In the present work, fluoroborondipyrrole (BODIPY) was assembled with cationic and anionic carbon dots (CDs) to construct positively charged (termed p-BDP) and negatively charged (termed n-BDP) nanophotosensitizers. Compared with n-BDP, p-BDP showed a stronger photoinactivation activity against Staphylococcus aureus, and its minimal inhibitory concentration (MIC) was as low as 128 ng mL−1. In addition, p-BDP could act as a more efficacious wound dressing to accelerate the healing of S. aureus infections. This work opens up alternative thinking for the design of highly effective nanobactericides. [ABSTRACT FROM AUTHOR]

At present, the use of hydrotalcite-like materials to remove fluoride from water is a relatively popular research topic. Herein, an experimental and theoretical study on the adsorption of F− on the surface of hydrotalcite was reported. The experiments indicate that adsorption reached equilibrium in 2 minutes. The experimental results of adsorption thermodynamics show that adsorption is spontaneous and endothermic. Calculations based on Density Functional Theory (DFT) and Molecular Dynamics (MD) simulation were used to research the adsorption of F− on the (0 0 3) crystal face of Cl−-hydrotalcite. The optimal geometric configuration of the adsorption of F− on different sites of the hydrotalcite surface was established. F− has the lowest adsorption energy (−300.565 kJ mol−1) at the vacancy above the aluminum atom and this configuration is the most stable. The analysis of the HOMO and LUMO and Fukui function results show that F− is more susceptible to electrophilic attack and adsorbed on the surface of hydrotalcite than Cl−. The calculation results of charge population and Partial Density Of States (PDOS) show that electron transfer occurred between F− and H on the surface of hydrotalcite laminates, and the strong hybridization of the F− 2p orbital with the H 1s orbital on the surface shows the formation of hydrogen bonds between them. The simulation results of adsorption thermodynamics are the same as the experimental results and the correctness of the experiment is verified. Finally, MD simulation was carried out to explain the effect of water on adsorption and confirmed the bonding mechanism. [ABSTRACT FROM AUTHOR]

The practicality of portable fluorescent detectors has attracted widespread attention. Herein, a series of luminogens was obtained via integrating pyrrole/fluorinated-pyrrole with triphenylamine in high yield. The emission performance was modified via varying the F and CN substituents on the pyrrole ring. The compounds TPACHO and TPAFCHO, with aldehyde-group-substituted pyrrole, exhibit significant mechanochromic luminescence (MCL) behavior and typical AIEE properties. The compounds TPA2CN and TPA2FCN can efficiently detect liquid and gaseous hydrazine hydrate, and they can achieve paper-based detection through visually clear emission color switching from yellow/orange to blue. The minimum detectable concentration of hydrazine was 10 mM. Moreover, TPA2CN exhibits good inhibitory activity toward human nasopharyngeal tumor cells (CNE1) and it has application prospects in tumor cell detection and biological cell monitoring. Thus, such functionalized paper can be applied as highly selective discriminating test strips for hydrazine hydrate. [ABSTRACT FROM AUTHOR]

The transformation of the piroxicam monohydrate to form I or form II could be achieved precisely by adjusting the particle size itself in a 99% acetone-1% H2O solvent at 31 °C. Mechanistic studies have demonstrated that the particle size could affect both the maximum concentration of piroxicam and the heterogeneous nucleation of form II during the solution-mediated phase transformation (SMPT) process, finally determining the polymorph outcome. [ABSTRACT FROM AUTHOR]

Conductive hydrogels have attracted widespread attention in wearable electronic devices and human motion detection. However, designing self-healing hydrogels with high conductivity and excellent mechanical properties remains a challenge. In this work, polyvinyl alcohol/carbon nanotubes/graphene (PVA/CNTs/graphene) with an island-bridge hydrogel structure and self-healing properties was designed by merging PVA/CNTs hydrogel and PVA/graphene hydrogel, in which the PVA/graphene hydrogel acts as an "island" and PVA/CNTs hydrogel acts as a "bridge" to bridge the entire conductive network. Hydrogen-bonding between the borate ion and the –OH group of PVA allows the conductive hydrogel to heal without any external stimulation. The PVA/CNTs/graphene hydrogel can be used for both stretchable strain and pressure sensors. The obtained PVA/CNTs/graphene composite hydrogel exhibits excellent electrical conductivity, extreme high elastic strain (up to 900%) and strong mechanical pressure (up to 10 kPa). The strain sensor based on the PVA/CNTs/graphene hydrogel exhibits excellent tensile strain sensitivity (a gauge factor of 152.6 in the strain region of 316–600%) and wide detection working range (1–600%) with high durability and repeatability. The sensor also remains highly sensitive when being used as a pressure sensor (−0.127 kPa−1 at 0–5 kPa). Additionally, the PVA/CNTs/graphene hydrogel-based sensor can detect human motions after multiple cuts and self-healing with excellent stability and repeatability. The PVA/CNTs/graphene hydrogel provides a new idea in the development of wearable electronics, demonstrating the potential of the next generation of wearable electronics. [ABSTRACT FROM AUTHOR]