Latest ArticlesRecently, MAX phases show great potential in lithium-ion uptake due to their excellent electrical conductivity and unique lamellar-structure accommodating lithium ions. However, the reports about MAX electrodes for lithium-ion battery up to now are relatively low. Herein we report the preparation of surface oxygen-deficient Ti2SC with abundant oxygen vacancies by a facile surface engineering method. When using as a lithium storage anode, this oxygen-deficient Ti2SC delivers a high capacity of 350 mAh/g at a current density of 400 mA/g as well as excellent rate performance, doubling the capacity compared to that of Ti2SC without oxygen vacancies. Confirmed by electrochemical impedance spectroscopy (EIS) and kinetic mechanism analyses, after reducing surface oxides and generation of oxygen vacancies, the as-received Ti2SC exhibits higher electrical conductivity and faster lithium ion diffusion. Thus this work offers a facial and effective strategy of optimizing the surface structure of MAX phases, further to achieve an enhanced lithium-ion uptake for lithium-ion batteries or capacitors.
The elaborate regulation of heterostructure interface to accelerate the interfacial charge separation is one of practicable approaches to improve the photocatalytic CO2 reduction performance of halide perovskite (HP) materials. Herein, we report an in-situ growth strategy for the construction of 2D CsPbBr3 based heterostructure with perovskite oxide (SrTiO3) nanosheet as substrate (CsPbBr3/SrTiO3). Lattice matching and matchable energy band structures between CsPbBr3 and SrTiO3 endow CsPbBr3/SrTiO3 heterostructure with an efficient interfacial charge separation. Moreover, the interfacial charge transfer rate can be further accelerated by etching SrTiO3 with NH4F to form flat surface capped with Ti−O bonds. The resultant 2D/2D T-SrTiO3/CsPbBr3 heterostructure exhibits an impressive photocatalytic activity for CO2 conversion with a CO yield of 120.2 ± 4.9 µmol g−1 h−1 at the light intensity of 100 mW/cm2 and water as electron source, which is about 10 and 7 times higher than those of the pristine SrTiO3 and CsPbBr3 nanosheets, surpassing the reported halide perovskite-based photocatalysts under the same conditions.
Metallacycles hold great promise for fluorescence-based sensing due to their synthetic advantages and unique physicochemical properties. However, it remains highly challenging to develop a versatile methodology for constructing highly emissive metallacycles with targeted functionalities and therefore sought-after properties. Herein, we report a general strategy to construct a series of highly emissive perylene diimide-based metallacycles via the self-assembly of perylene diimide-based tetrapyridyl ligand with different dicarboxylic ligands featuring fixed angles and cis-Pt(PEt3)2(OTf)2. Single crystal X-ray diffraction analyses verify the formation of bowtie-like metallacycles with two triangular cavities. Notably, the fluorescence quantum yields of most assemblies exceed 98%, amongst the highest values for metallacycles. Additionally, such metallacycles exhibit sensitive fluorescence responses toward picric acid with a detection limit of 2.8 × 10−6 mol/L. This study not only provides a rational strategy for preparing highly emissive bowtie-shaped metallacycles, but also sheds light on their usage in the detection of picric acid and associated compounds.
Naphthalimide derivatives have good planarity and large conjugated structure and therefore possess photophysical properties and biological activities. Previously, our group discovered seven-membered heterocyclic derivatives via modifying 4- and 5-positions of naphthalimide skeleton and found the derivatives had good water solubility and showed large stokes shift and strong fluorescence in water. In this article, we designed and synthesized more seven-membered ring-fused naphthalimide derivatives (Y1-Y16) by introducing different substitutions on the imide group. Among them, Y1, Y5, Y9 were found to show similar cytotoxic activities with Amonafide against A549 and HL60 cells, with IC50 values at 10−6 mol/L. What is more, the asymmetry derivatives (Y1 and Y5) showed high fluorescent quantum yields in the aqueous phase (Ф = 0.47). Considering the great fluorescence quantum yields in water and the potent anti-tumor activities of the representative seven-membered ring-fused naphthalimides, they have potentials to be used as agents for cancer theranostics.
The transformation of a Palladium-based metal-organic cage to a structurally similar one by direct ligand replacement usually leads to unwanted ligand scrambling. In this work, an intermediate ligand with different shape and basicity from the initial/final ones was introduced to avoid ligand scrambling to achieve the efficient indirect cage-to-similar-cage transformation. Compared with the direct transformation, the stepwise conversion has the advantages of high efficiency (93%) and simple workup.
Recently, hydrogen-bonding has attracted extensive attention in the design of chromophores. Here, a new class of hydrogen-bond locked purine chromophores (HOPs) were reported by introducing a hydroxyphenyl group into the C(6) position of purine. The intramolecular hydrogen bond plays a dominant role to light up these probes. As a bonus, HOPs show high photostability. Moreover, HOPs exhibit remarkable capability for the specific lipid droplets imaging in living cells with excellent biocompatibility and are also potential for diagnosing fatty liver diseases. These results bring important new insights into the photophysics of the purine-based chromophores and provide a new scaffold with high photostability for bioimaging.
Sulfur mustard (SM) can be absorbed by skin quickly and cause serious system damage via reacting with nearly all cell constituents. Until now, there is still lack of effective antidotal therapy for SM and skin protection is highly important to defend SM. In this article, supramolecular liquid barrier based on pillar[5]arene with triethylene oxide substituents (EGP5) has been designed to impede the skin permeation of SM and further interaction with the skin tissue. EGP5 could encapsulate SM within its cavity, with a Ka value of (5.10 ± 0.47) × 102 L/mol. In vitro skin absorption test proved that EGP5 was capable to effectively prevent SM from penetrating through skin. This supramolecular liquid barrier was employed on rat models to systematically evaluate protective effect against SM intoxication. Pretreatment of EGP5 could alleviate skin and system damage induced by SM and improve survival rate of poisoned rat models from 10% to 90%. Additionally, EGP5 served as protective materials could be highly reused after recycling several times. Overall, these findings have provided the first insight into the construction of convenient liquid material for SM protection.
Two red-emissive luminogens (TPTH and TPTB) with typical aggregation-induced emission characteristics were developed. By introducing the heavy atom of Br at the end of alkyl chain, TPTB exhibited higher reactive oxygen species generation efficiency through both types Ⅰ and Ⅱ pathways. Due to its excellent biocompatibility and proper lipophilicity, TPTB could be used for long-term cell membrane staining and this staining ability was independent of the change of plasma membrane potential. Furthermore, TPTB could ablate the cancer cells through cell membrane-targeted photodynamic therapy.
Biopolymer based hydrogels are highly adaptable, compatible and have shown great potential in biological tissues in biomedical applications. However, the development of bio-based hydrogels with high strength and effective antibacterial activity remains challenging. Herein, a series of vanillin-cross-linked chitosan nanocomposite hydrogel interfacially reinforced by g-C3N4 nanosheet carrying starch-caped Ag NPs were prepared for wound healing applications. The study aimed to enhance the strength, sustainability and control release ability of the fabricated membranes. Starch-caped silver nanoparticles were incorporated to enhance the anti-bacterial activities The fabricated membranes were assessed using various characterization techniques such as FT-IR, XRD, SEM, mechanical testing, Gel fraction and porosity alongside traditional biomedical tests i.e., swelling percentage, moisture retention ability, water vapor transmission rate, oxygen permeability, anti-bacterial activity and drug-release of the fabricated membranes. The mechanical strength reached as high as 25.9 ± 0.24 MPa for the best optimized sample. The moisture retention lied between 87%–89%, gel fraction 80%–85%, and water vapor transmission up to 104 ± 1.9 g m–2 h–1 showing great properties of the fabricated membrane. Swelling percentage surged to 225% for blood while porosity fluctuated between 44% ± 2.1% and 52.5% ± 2.3%. Oxygen permeability reached up to 8.02 mg/L showing the breathable nature of fabricated membranes. The nanocomposite membrane shown excellent antibacterial activity for both gram-positive and gram-negative bacteria with a maximum zone of inhibition 30 ± 0.25 mm and 36.23 ± 0.23 mm respectively. Furthermore, nanoparticles maintained sustainable release following non-fickian diffusion. The fabricated membrane demonstrated the application of inorganic filler to enhance the strength of biopolymer hydrogel with superior properties. These results envisage the potential of synthesized membrane to be used as wound dressing, artificial skin and load-bearing scaffolds.
Regulating flow direction of photo-excited electrons from interior to active sites in surface is critical to enhance the photocatalytic performance. Herein, photoinduced chemical reduction process was utilized to pinpoint deposit CdS and NiS nanodots sequentially onto g-C3N4 nanosheets. The resulted hybrid composite NiS/CdS/g-C3N4 was much more active under visible light, and eventually boosted the hydrogen evolution rate of 3015 µmol g−1 h−1, to be 2.4 folds better than that of g-C3N4. Because of the relative low content of CdS (around 3.0 wt%), the enhanced activity is due to the favoring band overlapping and promoting charge separation rather than increasing light absorption. Femto-second time-resolved transient absorption spectroscopy (fs-TAS) clearly reveals that the photo-excited electrons are from g-C3N4, and then migrate unidirectionally to CdS and finally to NiS, which is caused by the precisely regulate the position of CdS and NiS on g-C3N4 surface. This study elucidates the electron transfer kinetics and processes in multi-component system and affords a new avenue to construct stable photocatalysts with high activity.
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