Latest ArticlesThe intercalation behavior of spiro-(1,1′)-bipyrrolidinium cation (SBP+) into graphite electrode from spiro-(1,1′)-bipyrrolidinium tetrafluoroborate-ethylene carbonate (SBPBF4-EC) solutions is investigated by conventional electrochemical tests and in situ X-ray diffraction measurements. Two kinds of graphite intercalation compounds (GICs) with discrete characteristic intercalated gallery heights (IGHs) (ca. 0.95 and 0.75 nm) can be obtained with varying the salt concentration. The effect of graphite type is also addressed.
Sodium-ion batteries (SIB) have attracted widespread attention in large-scale energy storage fields owing to the abundant reserve in the earth and similar properties of sodium to lithium. Biomass-based carbon materials with low-cost, controllable structure, simple processing technology, and environmental friendliness tick almost all the right boxes as one of the promising anode materials for SIB. Herein, we present a simple novel strategy involving tea tomenta biomass-derived carbon anode with enhanced interlayer carbon distance (0.44 nm) and high performance, which is constructed by N, P co-doped hard carbon (Tea-1100-NP) derived from tea tomenta. The prepared Tea-1100-NP composite could deliver a high reversible capacity (326.1 mAh/g at 28 mA/g), high initial coulombic efficiency (ICE = 90% at 28 mA/g), stable cycle life (262.4 mAh/g at 280 mA/g for 100 cycles), and superior rate performance (224.5 mAh/g at 1400 mA/g). Experimental results show that the excellent electrochemical performance of Tea-1100-NP due to the high number of active N, P-containing groups, and disordered amorphous structures provide ample active sites and increase the conductivity, meanwhile, large amounts of microporous shorten the Na+ diffusion distance as well as quicken ion transport. This work provides a new type of N, P co-doped high-performance tomenta-derived carbon, which may also greatly promote the commercial application of SIB.
The unique components and architecture of Prussian blue analogous (PBAs) offer great potential for the construction of various functional nanostructures. Herein, we reported the preparation of a series of Mn–Fe oxides-based hybrids using Mn–Fe PBA as a template and an organic carbon source by calcination. The study focuses on revealing the interaction between the microstructure and electrochemical performance of the products obtained at different calcination temperatures. Notably, the as-derived porous Fe–Fe0.33Mn0.67O/C nanocubes (i.e., M600) exhibited the best rate capability and cycle life compared with other samples (~890 mAh/g at 0.1 A/g, 626.8 mAh/g after 1000 cycles at 1.0 A/g with a 99% capacity retention). These can be attributed to the fact that the porous structure provides shorter Li+ diffusion path and promotes the penetration of electrolyte. Besides, the N−doped C formed by the carbonization of organic ligands can buffer the volume change and prevent the aggregation of Fe0.33Mn0.67O nanoparticles during the discharge/charge cycles. Moreover, the presence of metallic Fe enhances the conductivity and the electrochemical activity, which accelerates the electrochemical reactions. Therefore, reasonable design of microstructure and compositions of functional nanocomposites is the key to obtain ideal electrochemical properties.
The layered heterometallic halide perovskites, as a newly explored material, have attracted great scientific attention. As one of the representatives of perovskite, lead-free or lead-substituted perovskite materials are widely applied in photovoltaic, sensors, catalysis, detectors and other fields. Therefore, it is urgent to carry out more systematic exploration and expand applicable preresearch, so as to make more interesting discoveries in this new hot spot. As an interesting candidate, heterometallic compounds will introduce more structural adjustability and novel physical properties, which is the main feature to be selected as the research hotspot. Here, we reported a lead-free bilayer heterometallic Ruddlesden-Popper (RP) type perovskite, [(MACH)2CsAgBiBr7] (MACH = cyclohexanemethylamine), which possesses a reversible phase transition at 379.6 K/375.1 K during heating-cooling cycle. Besides, it exhibits reddish-brown light emission under 365 nm, meanwhile, CIE chromaticity coordinate is (0.32, 0.45) on the yellow side and correlated color temperature is about 6000 K. Moreover, both the experimental data and theoretical calculation results suggest that [(MACH)2CsAgBiBr7] shows indirect semiconducting characteristics. In summary, this work will inspire the design of lead-free heterometallic perovskite materials for the application of sensors and light-emitting diodes (LEDs) fields.
Fluorescence detecting both organic and inorganic analytes has aroused tremendous scientific interests, because fluorescence techniques have high sensitivity and are easy to operate. A new three-dimensional (3D) MOF {[(CH3)2NH2][Zn3(bbip)(BTDI)1.5(OH)]·DMF·MeOH·3H2O}n (JXUST-13, bbip = 2,6-bis(benzimidazol-1-yl)pyridine and H4BTDI = 5,5′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diisophthalic acid) with new 4,4,8-connceted topology has been successfully synthesized and structurally characterized. Importantly, JXUST-13 could recognize H2PO4− and acetylacetone (Acac) by obvious fluorescence blue shift and slight enhancement with the detection limits of 2.70 µmol/L and 0.21 mmol/L, respectively. In addition, JXUST-13 exhibits relatively good thermal stability, chemical stabilities as well as reusability, and the analytes could be distinguished by naked eye and fluorescence test paper. Remarkably, JXUST-13 is the first dual-responsive MOF sensor based on fluorescence blue shift for the detection of H2PO4− and Acac with good selectivity in a handy, economic, and environmentally friendly manner.
The conversion of traditional polymolybdate-based metal-organic frameworks (POMOFs) crystals to well-aligned nanoarrays are highly attractive for electrocatalytic hydrogen evolution but remains significant challenge. Herein, we demonstrated that the POMOFs nanoarrays as self-supported electrode toward hydrogen evolution with high catalytic activity and stability. Single-crystal X-ray analysis reveal the {ε-PMo8VMo4VIO37Zn4} (Zn-ε-Keggin) serve as secondary building blocks and directly connected to BPB organic ligands (BPB = 1, 4-bis(pyrid-4-yl)benzene) to obtain novel [ε-PMo8VMo4VIO37(OH)3Zn4][BPB]3 (named as ZnMo-POMOF). Particularly, ZnMo-POMOF nanoflower arrays grown in-situ on a Ni foam substrate exhibiting excellent electrocatalytic hydrogen evolution performance of 180 mV at a current density of 10 mA/cm2 with the Tafel slope of 66 mV/dec, thus among one of the best POMOF-based electrocatalysts reported so far. DFT calculations reveal that the bridging oxygen active sites (Oa) significantly optimizes Gibbs free energy of H* adsorption for Zn-ε-Keggin polymolybdate units (−0.07 eV), thereby increasing the intrinsic activity of the ZnMo-POMOF.
Surface-enhanced Raman spectroscopy (SERS), a powerful surface vibrational spectroscopic technique, is ideally suited for in situ monitoring the chemical transformations occurred at surfaces and/or interfaces. For in situ SERS monitoring, a platform integrated both plasmonic and catalytic activity is a prerequisite. Here, we fabricate a bifunctional Au-Pd nanocoronal film for in situ SERS monitoring Suzuki-Miyaura cross-coupling reaction. This excellent bifunctional substrate leads to the coupling of high catalytic activity with a strong SERS effect at the center of two adjacent Au cores and shows fine reproducibility and stability of SERS signals. During investigating the Suzuki reaction with in situ SERS, we found two distinct catalytic kinetic processes resulted from two disparate catalytic sites on a Au-Pd nanocoronal. Comparing with conventional analytical techniques, this work provides a novel approach for studying Suzuki reactions at surfaces and/or interfaces with in situ SERS.
T4 polynucleotide kinase (T4 PNK) is a pivotal enzyme for DNA replication, recombination, and DNA damage repair. Herein, a robust single particle counting-based assay has been developed for the high-sensitive determination of T4 PNK activity through only a simple one-step reaction. Taking benefit of the exceptional space-confined enzymatic property of T4 PNK towards DNA substrates on a single nanoparticle, the T4 PNK activity can be precisely determined by counting the fluorescence-positive nanoparticles in a digital manner with a total internal reflection fluorescent microscope (TIRFM). Due to the featured spatial-confined enzymatic property of T4 PNK and the single particle counting-based signal readout, T4 PNK can be effectively differentiated from other interfering enzymes. This facile strategy has been also successfully applied to screen T4 PNK inhibitor and accurately determine T4 PNK activity in complex biological samples, paving a potential avenue for the digital analysis of biomarkers.
Chemodynamic therapy (CDT) is a promising therapeutic approach for in situ cancer treatment, but it is still hindered by inefficient single-modality treatment and the weak targeted delivery of reagents into mitochondria (the main site of intracellular ROS production). Herein, to obtain a multimodal strategy, peptide-assembled siRNA nanomicelles were prepared to confine ultrasmall MnO in small silica cages (silicages), which is convenient for synergistic chemical and gene-regulated cancer therapy. Given the free energy and versatility of small silicages, as well as the excellent Fenton-like activity of ultrasmall MnO, MnO-inside-loaded silicages (10 nm) were prepared for CDT delivery to mitochondria. Subsequently, to obtain a synergistic CDT and gene silencing treatment, the peptide-mediated assembly of siRNA and MnO-loaded silicages were employed to obtain silicage@MnO-siRNA nanomicelles (SMS NMs). After multiple modifications, sequential cancer cell-targeted delivery, GSH-controlled reagent release of siRNA and mitochondria-targeted delivery of MnO-loaded silicages were successfully achieved. Finally, by both in vitro and in vivo experiments, SMS NMs were confirmed to be effective for synergistic chemical and gene-regulated cancer therapy. Our findings expand the applications of silicages and initiate the development of multimodal CDT.
To explore the lead-free key scientific issue in perovskite, double perovskite based on AgBi and CuBi was naturally selected as a competitive candidate due to its fascinating functional features, such as self-powered circularly polarized light detection, X-ray detection, photoluminescence and so on. However, the most challenging point is to simulate the structure and function of traditional lead-based perovskite in new double perovskite. At the same time, there are few suitable double perovskite systems with optical and electrical potential. The above two points greatly limit the competitiveness of double perovskite. In order to solve this problem, firstly, by analyzing and comparing previous studies, we used 2,2-dimethylpropan-1-aminium (abbreviated as 2,2-DPA) as the organic template to assemble materials. Solid-to-solid phase transition materials (2,2-DPA)3Bi2I9 1 and (2,2-DPA)3Pb2I7 2 were constructed. Along the path of lead-free and two-dimensional maintenance, we successfully synthesized (2,2-DPA)4AgBiI8·H2O 3 and (2,2-DPA)4CuBiI8·H2O 4. As two typical semiconductors, 3 and 4 with narrower optical band gaps of 1.98 and 1.76 eV show obvious photo-response when the xenon lamp with intensity of 20 mW/cm2 is on or off, implying that they may be applied to light-harvesting and light-detecting devices. By referring to the phase transition mechanism of 1 and 2, 3 may be caused by ordered-disordered transition of the organic part, which was proven to be the first solid-to-solid phase transition material with <100> -oriented layered double perovskites with n = 1 by systematic characterization methods after dehydration for all we know. We believed that this work can provide meaningful guidance for the development of lead-free double perovskites.
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