Latest ArticlesPerovskite quantum dots (PQDs) possess remarkable optical properties, such as tunable photoluminescence (PL) emission spectra, narrow full width at half maximum (FWHM) and high PL quantum yield (QY), endowing the PQDs great application prospects. However, the inherent structural instability of PQDs has seriously hindered the application of PQDs in various photoelectric devices. In this work, a microfluidic electrospinning method was used to fabricate color-tunable fluorescent formamidinium lead halogen (FAPbX3, X = Cl, Br, I) PQDs/polymer core-shell nanofiber films. The core-shell spinning nanofiber not only supplies the interspace for the in-situ formation of PQDs, but also significantly reduces the permeability of moisture and oxygen in the air, which greatly improves the stability of PQDs. After adjusting the composition of precursors, the blue-emissive polystyrene (core) and polymethyl methacrylate (shell) coated FAPbCl3 QDs (abbreviated as PS/FAPbCl3/PMMA, hereinafter), green-emissive PS/FAPbBr3/PMMA and red-emissive PS/FAPbI3/PMMA nanofiber films were fabricated with the highest PL QY of 82.3%. Moreover, the PS/FAPbBr3/PMMA nanofiber film exhibits great PL stability under blue light irradiation, long-term storage in the air and water resistance test. Finally, the green- and red-emissive nanofiber films were directly applied as light conversion films to fabricate wide-color-gamut display with the color gamut of 125%, indicating their tremendous potentials in optoelectronic applications.
In this study, we proposed a novel method to investigate the advanced oxidation process of neonicotinoids (NNIs) from the perspective of concomitant chemiluminescence (CL) reaction. It was found that in the presence of cobalt ions with cyanoimino NNIs, acetamiprid (ACE) and thiacloprid (THI), could promote peroxymonosulfate and Ru(bpy)32+ to produce strong CL, but no CL occurred with nitro-involved NNIs as alternatives. Experimental dada from UV absorption spectra and chemiluminescence spectra suggested that new cyclic compounds might be formed during the reaction. Based on the results of free radical scavenging experiment and mass spectra, a new degradation and reaction mechanism of cyanoimino-containing NNIs was proposed. ACE or THI were first attacked by SO4•− to form benzyl radicals, which in turn reacted with the carbon atoms of cyano group through electrophilic addition reaction in the formation of intramolecular ring. Then a redox reaction between Ru(bpy)33+ and imino group immediately took place with CL emission (610 nm). The new mechanistic knowledge would be meaningful for other contaminants for their interactions with PMS.
Potassium ion batteries (PIBs) have been regarded as promising alternatives to lithium ion batteries (LIBs) on account of their abundant resource and low cost in large scale energy storage applications. However, it still remains great challenges to explore suitable electrode materials that can reversibly accommodate large size of potassium ions. Here, we construct oxygen-deficient V2O3 nanoparticles encapsulated in amorphous carbon shell (Od-V2O3@C) as anode materials for PIBs by subtly combining the strategies of morphology and deficiency engineering. The MOF derived nanostructure along with uniform carbon coating layer can not only enables fast K+ migration and charge transfer kinetics, but also accommodate volume change and maintain structural stability. Besides, the introduction of oxygen deficiency intrinsically tunes the electronic structure of materials according to DFT calculation, and thus lead to improved electrochemical performance. When utilized as anode for PIBs, Od-V2O3@C electrode exhibits superior rate capability (reversible capacities of 262.8, 227.8, 201.5, 179.8, 156.9 mAh/g at 100, 200, 500, 1000 and 2000 mA/g, respectively), and ultralong cycle life (127.4 mAh/g after 1000 cycles at 2 A/g). This study demonstrates a feasible way to realize high performance PIBs through morphology and deficiency engineering.
Ammonia is the feedstock chemical for most fertilizers and the alternative of renewable energy carriers. Environmentally benign electrochemical nitrogen reduction reaction (NRR) under mild conditions has been recognized as one of the most attractive strategies for N2 fixation. Herein, inspired by Mo-based nitrogenase, W/Mo-doping electrocatalysts were developed with mixed-metal polyoxometalate H3PW6Mo6O40 as the precursor for high performance electrocatalytic NRR. Trace amount of Pt was transplanted on the surface of W/Mo@rGO via in situ electroplating treatment to further improve the NRR performance. The resulting Pt-W/Mo@rGO-6 achieves excellent performance for NRR with a high NH3 yield of 79.2 µg h−1 mgcat−1 due to the multicomponent synergistic effect in the composite catalyst. The Pt-W/Mo@rGO-6 represents the first example of highly efficient NRR electraocatalyst derived from mixed-metal polyoxometalate, which exhibits outstanding stability confirmed by the constant catalytic performance over 24 h chronoamperometric test. This finding opens a new avenue to construct highly efficient NRR electrocatalyst by employing mixed metal polyoxometalate as the precursor under ambient conditions.
Na-CO2 batteries have attracted extensive attention due to their high theoretical energy density (1125 Wh/kg), efficient utilization of CO2, and abundant sodium resources. However, they are trapped by the sluggish decomposition kinetic of discharge products (mainly Na2CO3) on cathode side during the charging process. Here we prepared a series of nano-composites composed of RuO2 nanoparticles in situ loaded on activated multi-walled carbon nanotubes (RuO2@a-MWCNTs) through hydrolyzing reaction followed by calcination method and used them as cathode catalysts to accelerate the decomposition of Na2CO3. Among all catalysts, the RuO2@a-MWCNTs with appropriate ratio of RuO2 (49.7 wt%) demonstrated best stability and rate performance in Na-CO2 batteries, benefiting from both high specific surface area (160.3 m2/g) and highly dispersed RuO2 with ultrafine nanostructures (~2 nm). At a limited capacity of 500 mAh/g, Na-CO2 batteries could afford the operation of over 120 cycles at 100 mA/g, and even at the current density to 500 mA/g, the charge voltage was still lower than 4.0 V after 40 cycles. Further theoretical calculations proved that RuO2 was the catalytically active center and contributed to the decomposition of Na2CO3 by weakening the C=O bond. The synergetic functions of high specific surface (CNTs) and high catalytic activity (RuO2) will inspire more progress on metal-CO2 batteries.
Although many plasmonic nanosenosrs have been established for the detection of mercury(Ⅱ) (Hg2+), few of them is feasible for analyzing natural samples with very complex matrices because of insufficient method selectivity. To address this challenge, we propose an epitaxial and lattice-mismatch approach to the synthesis of a unique Au/Ag2S dimeric nanostructure, which consists of an Au segment with excellent plasmonic characteristics, and a highly stable Ag2S portion with minimum solubility product (Ksp(Ag2S) = 6.3 × 10−50). The detection relies on the chemical conversion of Ag2S to HgS when reacting with Hg2+, resulting in a red shift in the absorption band of the connecting Au NPs. The concurrent color changes of the solution from gray purple to dark green and finally to navy correlate well with Hg2+ concentration, thus enables UV–vis quantitation and a naked-eye readout of the Hg2+ concentration. This method exhibits superior selectivity towards Hg2+ over other interfering ions tested because Hg2+ is the only ion that can react with Ag2S to form HgS with even smaller solubility product (Ksp(HgS) = 4 × 10−53). The detection limit of this method is 1.21 µmol/L, calculated by the signal-to-noise of 3. The practicability of the method was verified by analyzing the Hg2+ in sewage water samples without sample pretreatment with satisfactory recoveries (93.1%-102.8%) and relative standard deviations (1.38%-2.89%). We believe this method holds great potential for on-the-spot detection of Hg2+ in environmental water samples with complex matrices.
Surface charge transfer doping of graphene plays an important role in graphene-based electronics due to its simplicity, high doping efficiency, and easy-controllability. Here, we demonstrate the effective surface charge transfer hole doping of graphene by using a strong p-type molecular dopant hexacyano-trimethylene-cyclopropane (CN6-CP). The CN6-CP exhibits a very high intrinsic work function of 6.37 eV, which facilitates remarkable electron transfer from graphene to CN6-CP as revealed by in situ photoelectron spectroscopy investigations. Consequently, hole accumulation appears in the graphene layer at the direct contact with CN6-CP. As evidenced by Hall effect measurements, the areal hole density of graphene significantly increased from 8.3 × 1012 cm−2 to 2.21 × 1013 cm−2 upon 6 nm CN6-CP evaporation. The CN6-CP acceptor with strong p-doping effect has great implications for both graphene-based and organic electronics.
In this paper, we designed a three-dimensional cell co-cultured microfluidic chip, which generated interstitial flow and oxygen gradient to simulate the complex tumor microenvironment. It consisted of five parallel cell culture channels and one hypoxic channel. These channels were constructed for the culture of mouse liver tumor cells (Hepa1-6), mouse liver stellate cells (JS-1), the simulation of extracellular matrix, complex biochemical factors (hypoxia and interstitial flow), and the supply of cellular nutrients. The 3D-interstitial flow-hypoxia model was used to study the behavior of JS-1 cells under the effect of tumor microenvironment (TME). The results showed that by co-cultured with Hepa1-6 cells, hypoxia of Hepa1-6 cells, and adding TGF-β1 by interstitial flow, the migration of JS-1 cells could be promoted. Similarly, activated JS-1 cells could led to the epithelial-mesenchymal transformation in co-cultured Hepa1-6 cells, which secreted more TGF-β1.
Many evolved biomolecular functions such as ion pumping or redox catalysis rely on controlled charge transport through the polypeptide matrix, which can be regulated by shifts in molecular protonation states and dependent supramolecular packing modes in response to environmental cues. However, the exact roles of such dynamic, non-covalent interactions in peptide charge transport have remained elusive. To tackle this challenge, here we report the modulation of charge transport in a series of lysine (Lys)-substituted hepta-glycine (Gly) peptide self-assembled monolayers (SAMs) on template-striped gold (AuTS) bottom electrodes with eutectic gallium-indium (EGaIn) liquid metal top electrodes. We demonstrate systematic modulation of hydrogen bonding and more general electrostatic interactions by shifting the position of the charged Lys-residue and creating different protonation patterns by changing the environmental pH in the AuTS/peptide//GaOx/EGaIn junctions. The effective modulation is evidenced by current density–voltage (J-V) measurements combined with SAM characterization using ultraviolet photoelectron spectroscopy (UPS) and angle-resolved X-ray photoelectron spectroscopy (ARXPS), polarization modulation–infrared reflection-absorption spectroscopy (PM-IRRAS), and molecular dynamics (MD) simulations. Decreasing the hydrogen bonding inside the peptide SAMs and increasing the electrostatic interactions by environmental counterions amplifies the charge transport differently with Lys-position, which means that the sensitive electrical response of peptide SAMs can be tuned by the peptide sequence. Our results provide insights into the relationship between molecular design and in situ modulation of charge transport properties for the development of bionanoelectronics.
Three novel dithienylethenes modified by bifluoroboron β-diketonate fragments have been successfully developed. Upon blue light irradiation, they reached photostationary state within 2–5 s, as well as 100% conversion ratio and photocyclization quantum yield of > 0.70. Such fascinating photochromism were endowed by collaborative role of electron-withdrawing effect of BF2bdk group to reduce HOMO-LUMO electronic gap for the open isomer, together with intramolecular hydrogen bonds and CH-π interactions favoring antiparallel conformation fixation. Moreover, they displayed specific discrimination and photoswitchable bacterial imaging for S. aureus.
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