Latest ArticlesMetal oxides derived from metal-organic framework (MOF) have attracted considerable attention due to its excellent performance and unique structure. Doping is considered as an effective method to improve gas-sensing performance. However, nonmetal doped metal oxides derived from MOF as gas-sensing materials have not been reported. Within this work, N atoms were successfully doped into the lattice of ZnO nanoparticles using ZIF-8 as a self-sacrificial template through a thermal treatment process with the assistant of urea. The obtained N-ZnO exhibited competitive ethanol-sensing performance, in which the response value of N-ZnO-5 to 100 ppm ethanol reached 115 at 190 ℃ with a satisfactory selectivity. It was found that the N-doping in ZnO facilitated the formation of oxygen vacancy that promoted the generation of adsorbed oxygen species to achieve the enhanced gas-sensing performance. Besides, the larger specific surface area resulting from the size reduction during the urea-assisted pyrolysis process can also be responsible for the improving of the ethanol-sensing performance.
Acetylene (C2H2) and ethylene (C2H4) both are important chemical raw materials and energy fuel gasses. But the effective removement of trace C2H2 from C2H4 and the purification of C2H2 from carbon dioxide (CO2) are particularly challenging in the petrochemical industry. As a class of porous physical adsorbent, metal-organic frameworks (MOFs) have exhibited great success in separation and purification of light hydrocarbon gas. Herein, we rationally designed four novel MOFs by the strategy of pore space partition (PSP) via introducing triangular tri(pyridin-4-yl)-amine (TPA) into the 1D hexagonal channels of acs-type parent skeleton. By modulating the functional groups of linear dicarboxylate linkers for the parent skeleton, a series of isoreticular PSP-MOFs (SNNU-278−281) were successfully obtained. The synergistic effects of suitable pore size and Lewis basic functional groups make these MOFs ideal C2H2 adsorbents. The gas adsorption experimental results show that all MOFs have excellent C2H2 uptakes. Specially, SNNU-278 demonstrates a high C2H2 uptake of 149.7 cm3/g at 273 K and 1 atm. Meanwhile, SNNU-278−281 MOFs also show extremely great C2H2 separation from CO2 and C2H4. The optimized SNNU-281 with high-density hydroxy groups exhibits extraordinary C2H2/CO2 and C2H2/C2H4 dynamic breakthrough interval times up to 31 min/g and 17 min/g under 298 K and 1 bar.
Graphene-polymer composites have attracted great attention as sensing materials due to their tailorable electrical conductivity, physicochemical properties, and sensitivity to geometric and functional changes. Herein, we report the first example of cylindrical monolithic polyimine vitrimer/graphene composites with excellent mechanical, compressive, rehealable and recyclable, and piezoresistive properties via simple infiltration of polymer monomers into the pores of graphene aerogel followed by thermal curing. The composites exhibit excellent durable compressibility (negligible reduction in the compression properties even after 3000 consecutive compression cycles), rapid recovery to the original size upon stress released, high compressive strength (up to 1.2 MPa), and high conductivity (up to 79 S/m). Excellent piezoresistive properties were observed, displaying consistent and reliable change of the electrical resistance with the compression ratio. Furthermore, rehealing with ~100% recovery of the compressive strength and electric conductivity was achieved under mild rehealing conditions, which is highly desired but has rarely been reported for electronic materials. The facile strategy for fabrication of rehealable monolithic polymer/GAs can open new possibilities for the sustainable development of composites with high electrical conductivity for various applications such as sensing, health monitoring, and movement detection.
The effective design and synthesis of novel small-molecule donors (SMDs) is extremely essential for the in-depth study of the scientific problems of bulk heterojunction morphology and the improvement of photovoltaic performance in organic solar cells (OSCs). Importantly, developing a series of donors with different conjugated central donor (D) units is a remarkable strategy to obtain high-performance donors. Herein, two acceptor-donor-donor-acceptor (A-D-D-A) type oligomeric donors 2DTBDT and 2DTBDT-2T with two dithieno[2, 3-d: 2′, 3′-d']benzo[1, 2-b: 4, 5-b']dithiophene (DTBDT) as D units, without and with bithiophene as the π bridge respectively are designed and synthesized successfully. The central linked-DTBDT unit can provide a larger conjugated plane and promote π electron delocalization, which can effectively improve π-π interactions between donors and regulate the crystallinity. And we found that the π bridge provided 2DTBDT-2T with 12.31% efficiency that is already a high efficiency in OSCs, whereas 2DTBDT with merely 3.63% efficiency, both with 2, 2′-((2Z, 2′Z)-((12, 13-bis(2-ethylhexyl)-3, 9-diundecyl-12, 13-dihydro-[1,2,5]thiadiazolo[3, 4-e]thieno[2, "3′': 4′, 5′]thieno[2′, 3′: 4, 5]pyrrolo[3, 2-g]thieno[2′, 3′: 4, 5]thieno[3, 2-b]indole, 10-diyl)bis(methanylylidene))bis(5, 6-difluoro-3-oxo-2, 3-dihydro-1H-indene-2, 1-diylidene)) dimalononitrile (Y6) as the acceptor. We conjecture that the main reason for the different device performance may be ascribed to the different molecular stacking orientation of the oligomeric donors and morphology features of the donors: Y6 blend films. Compared to the predominant face-on orientation of the 2DTBDT neat film, the 2DTBDT-2T neat film performed a preferential edge-on orientation, which obtained a smoother surface, stronger crystallinity and more uniform phase separation in the 2DTBDT-2T: Y6 blend films with nanofiber structure, which delivered higher and more balanced carrier mobilities, the more efficient exciton dissociation and reduced biomolecule recombination, therefore obtaining better power conversion efficiencies (PCEs). We speculate that the transformation of molecular stacking orientation of oligomeric donors is possibly due to that π bridge extended and twisted the molecular structure of 2DTDBT-2T, resulting in an edge-on orientation relative to the substrate. These findings demonstrate that the single-bond-linked donor strategy is an alternative method to design the donors towards high-performance OSCs.
Intracellular pH undertakes critical functions in various biological and pathological processes. It is important to monitor intracellular pH fluctuations for understanding physiological and pathological processes. Here, one aldehyde-bearing cyclometalated iridium(Ⅲ) complex ([(4-pba)2Ir(dcphen)]PF6, 4-pba = 4-(2-pyridyl) benzaldehyde, dcphen = 4, 7-dichloro-1, 10-phenanthroline, probe 1) was synthesized and used to track intracellular pH fluctuations. Probe 1 displayed pH-dependent luminescence property in pH range of 1.81–6.81 with an evaluated pKa value of 4.30 in BR buffer-DMSO (v:v = 99:1). An intramolecular hydrogen bonds assisted pH-responsive mechanism was proposed for the pH-responsive behavior of probe 1. Probe 1 was successfully applied for imaging and tracking pH fluctuations in HeLa cells under external stimulation with fast response time, good photostability as well as low cytotoxicity and high cell permeability. This work demonstrates that aldehyde-bearing cyclometalated iridium(Ⅲ) complex can be used as alternative pH-responsive probe for real-time tracking intracellular pH fluctuations, which provides a strategy for the design of pH-responsive probe in versatile applications.
As an emerging energy storage device with high-safety aqueous electrolytes, low-cost, environmental benignity and large-reserves, the rechargeable aqueous zinc-ion batteries (AZIBs) have attracted more and more attention. Vanadium-based compounds are also supposed as the potential candidate cathode materials for AZIBs due to their wide variety of phases, variable crystal structures and high theoretical capacity. In this review, the recent progress in the development of vanadium-based materials was summarized, and the relationship between the crystal structure types of active materials and Zn-ion transport mechanism was highlighted. During the charge-discharge process, the different electrostatic repulsion between the cations of vanadium-based compounds with different crystal structures and Zn2+ results in a variety of the Zn-ion storage mechanisms, which can be significant guidance for designing the advanced battery-electrode materials for AZIBs. Furthermore, other factors associated with the storage mechanisms, such as electrolyte components and electrode morphology, are discussed. Finally, the strategies to improve the electrical conductivity, inhibit the dissolution and stabilize the crystal structure of vanadium-based compounds are proposed and the future prospects for developing high-energy-density AZIBs are presented.
The development of high-performance non-precious metal-based robust bifunctional electrocatalyst for both hydrogen evolution reaction (HER) and oxygen evolution reactions (OER) in alkaline media is essential for the electrochemical overall water splitting technologies. Herein, we demonstrate that the HER/OER performance of CoSe2 can be significantly enhanced by tuning the 3d-orbital electron filling degree through Mo doping. Both density functional theory (DFT) calculations and experimental results imply that the doping of Mo with higher proportion of the unoccupied d-orbital (Pun) could not only serve as the active center for water adsorption to enhance the water molecule activation, but also modulate the electronic structures of Co metal center leading to the optimized adsorption strength of *H. As expected, the obtained Mo-CoSe2 exhibits a remarkable bifunctional performance with overpotential of only 85 mV for HER and 245 mV for OER to achieve the current density of 10 mA/cm2 in alkaline media. This work will provide a valuable insight to design highly efficient bifunctional electrocatalyst towards HER and OER.
MicroRNAs (miRNAs) have attracted significant attention in biomedical research and clinical diagnosis. However, due to their inherent characteristics of low abundance and the high complexity of corresponding biological matrices, simultaneous detection of multiple miRNAs at low abundance is still a challenge. In this work, a method coupling exponential amplification reaction (EXPAR) with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is developed for label-free and simultaneous detection of multiple miRNAs. The assay can be performed under isothermal conditions in a single reaction tube, and finished in less than 30 min. It exhibits good quantification ability and with attomolar-level sensitivity for miRNAs detection. It also shows high specificity to distinguish miRNAs at single-nucleotide resolution. We used the method to detect the miRNA-21, let-7a, miRNA-100, and miRNA-125b in samples of spiked human serum and breast cancer cells (i.e., MCF-7, MDA-MB-231 and SK-BR-3). The quantification results were well consistent with the standard real-time fluorescence EXPAR. Consequently, the label-free mass-spectrometric platform could be a potential tool for miRNAs analysis in complex biological samples, and may be used for clinical diagnosis.
Black phosphorus (BP) as an uprising two-dimensional material exhibits attractive potential in the field of electrocatalysis due to the inherent advantages of high carrier mobility and abundant lone pair electrons. However, the exposed active electrons compel BP to be deactivated by oxidative degradation. Herein, the electronic signature of acceptor-donor heterointerfacial interactions between BP and Co3O4 is realized via wet ball milling. The preferential migration of active electrons from BP to Co3O4 is achieved at the heterointerface since the Fermi level of BP is higher than that of Co3O4. Such relative energetic consideration promotes reasonable oxygen electrocatalytic active sites. Moreover, it significantly suppresses the oxidative degradation of BP. Consequently, the resulting Co3O4/BP heterojunction possesses superior oxygen bifunctional electrocatalytic activity than its parent catalysts. Most importantly, this work promotes an efficient route towards BP-based multifunctional catalysts.
Rhein (Rhe), an anthraquinone derivative, exhibits excellent anti-inflammatory effects and other pharmacological activities, but its clinical application remains limited due to poor solubility. The present work aims at the improvement of solubility and oral bioavailability of Rhe through cocrystal formation. For this purpose, Rhe and matrine (Mat) were selected as pharmaceutical ingredient (API) and cocrystal former (CCF), respectively, and the Rhe-Mat cocrystal was synthesized and characterized by single crystal X-ray diffraction (SXRD), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC). The formation mechanism of Rhe-Mat cocrystal was elucidated by molecular surface electrostatic potential (MSEP). It is worth mentioning that the 50-fold increment of dissolution in vitro was observed in pure water in the form of Rhe-Mat cocrystal. Furthermore, the in vivo studies revealed that Rhe-Mat cocrystal indicated the faster absorption rate and the higher peak blood concentration than the pure Rhe. Hence, it can be concluded that current study successfully improved the solubility and oral bioavailability of Rhe.
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