The co‐assembly of spherical colloids and surfactant–cyclodextrin microtubes yields a library of dynamic colloid‐in‐tube structures, including helices. In situ observations of these structures, ...including their thermo‐reversible assembly and disassembly, demonstrate the potential of the interplay between molecular and colloidal self‐assembly, thereby providing a novel route to temperature‐sensitive particle alignment and release.
•Synthesized a unique naphthalimide-rhodamine based chemosensor (NR-HG) for the selective detection of Hg2+ ion.•NR-HG shows an impressive LOD 491 nM and exhibits reversibility.•Synthesized Probe ...works through PET, CHEF, and FRET leading to the chelation-induced ring opening.•TD-DFT calculation supported the origin of the fluorescence emission maxima.•NR-HG is stable in biological pH and can efficiently image Hg2+ in SiHa cells under the fluorescence microscope.
In this work, we are presenting the design and synthesis of an innovative fluorescent chemosensor: NR-HG, established on a naphthalimide-based rhodamine platform for Hg2+ ion sensing. The probe operates via PET, CHEF, and FRET mechanisms. The fluorescent chemosensor shows an immense selectivity and sensitivity towards Hg2+ ion via the enhancement of ring-opening rhodamine spiro-cyclic structure, with a detection limit (LOD) of 491 nM. The DFT analysis strongly validates the experimental observations. The probe senses the Hg2+ ion reversibly upon the addition of potassium iodide (KI). From the analysis of Job’s plot, it can be conclusively confirmed that the NR-HG-Hg2+ complex demonstrates a 1:1 stoichiometric ratio. We also conducted an MTT assay and cell imaging experiment to assess both the compatibility of the probe with living cells and its effectiveness in real-life imaging.
•Zn electrode performance in different electrolytes is systematically evaluated.•Zn electrode in mild/slightly acid electrolytes exhibits better cycling stability.•Alkaline electrolyte promises a ...rapid electrode kinetics and a small hysteresis.•Mild/slightly acid electrolytes endow high reversibility.
Zn-based batteries attract extensive attention as the next-generation energy storage devices for both electronics and large power grids due to the high capacity, energy density, low cost, and safety derived from the inherent properties of metallic Zn and the safety of aqueous electrolytes. Herein, the performance variations and critical issues of the Zn electrodes in the alkaline and neutral/slightly acid electrolytes are systematically investigated by evaluating the cycle stability, electrode reaction kinetics, and stripping/plating reversibility in three kinds of electrolytes, including ZnSO4, Zn(CF3SO3)2, and KOH+Zn(CH3COO)2. The lifespan of the Zn electrode in the neutral/slightly acid electrolytes is >1400% higher than the one in the alkaline electrolyte at a current density of 1 mA cm−2. However, the Zn electrode in the alkaline solution exhibits better reaction kinetics and low polarization. Besides, in the neutral/slightly acid electrolytes, higher coulombic efficiency is obtained, corresponding to better stripping/plating reversibility. Therefore, research in neutral/slightly acid electrolytes should focus on elevating the electrode kinetics and reducing polarization, while in alkaline electrolytes, the dendrite, hydrogen evolution, and self-discharge should be treated to elevate the calendar life and reversibility. This work provides a guideline for further construction of high-performance Zn electrodes in different electrolyte systems.
Display omitted
Display omitted
•The onset dehydrogenation temperature of Mg(BH4)2 is reduced to 105.4 °C and 108.0 °C with K2TiF6 and K2NbF7.•The partial reversibility of Mg(BH4)2 is enhanced to 2.7 wt% with ...K2TiF6.•K2TiF6 can react with Mg(BH4)2 to form KBH4 and TiH2, which serve as catalyzing agents.
Two dual-cation transition metal fluorides K2TiF6 and K2NbF7 are introduced into Mg(BH4)2 by ball-milling to catalyze the dehydrogenation of Mg(BH4)2. According to the DSC and TPD results, the onset dehydrogenation temperature of Mg(BH4)2 doped with K2TiF6 and K2NbF7 are remarkably reduced to 105.4 and 118.0 °C, respectively. Meanwhile, both the K2TiF6 and K2NbF7 catalyzed systems can release more than 6.4 wt% H2 under 280 °C, showing an improvement in dehydrogenation kinetics. In addition, the reversible capacity of the Mg(BH4)2–3%K2TiF6 system is 2.7 wt% at 280 °C in 250 min, which is enhanced comparing to that of pristine Mg(BH4)2. X-ray diffraction, Fourier-transformed infrared and 11B nuclear magnetic resonance investigations reveal that the K2TiF6 actually acts as a catalytic precursor to react with Mg(BH4)2, forming active hydrides of KBH4 and TiH2, which further serve as catalyzing agents to facilitate the re-generation of Mg(BH4)2 from intermediates under moderate conditions.
Display omitted
•3D host-lithium composite (HLC) anode was fabricated by thermal Li impregnation.•HLC is accessible to attain a uniform Li-ion flux.•Homogeneous distribution of Li-ion prevents from ...the degradation of Li metal anode.•The reaction in anode largely determines reversibility of Li2O2 on cathode.
This paper reports use of a 3D porous Cu scaffold as a conductive host in the 3D host-lithium composite anode (HLC) in Li-O2 batteries to decrease local current density and induce uniform Li deposition, and thereby suppress formation of Li dendrites that reduce rate capability and reversibility of the batteries. Furthermore, the influences of HLC and uniform Li-ion flux on Li2O2 formation at the porous cathode were investigated by quantification of Li2O2. The amount of Li2O2 on cathodes changed according to the state of the facing Li anodes; this trend means that the influence of uniform Li-ion flux from the Li metal anode is critical to ensure uniform Li2O2 formation at the cathode. The results confirmed that the HLC ensures uniform formation and decomposition of Li2O2 at the cathode.
Cells based on proton-conducting ceramics (PCC) working at intermediate temperatures have intrinsic properties that suggest promising potential applications. Currently, almost all the literature in ...the field of PCC has focused on hydrogen conversion (Protonic Ceramic Fuel Cell PCFC) and/or hydrogen production (Protonic Ceramic Electrolysis Cell PCEC). Very few studies have inspected the reversibility of these systems (RePCC) in order to understand their potential coupling to intermittent renewable energies. Despite the promising results achieved, the development of these technologies remains very challenging.
The work presented here illustrates the fabrication and the characterization of a 32 mm–diameter hydrogen-electrode-supported cell. A double perovskite with general formula AA’BB’O5+δ is used as air electrode material (SmBa0.5Sr0.5Co1.5Fe0.5O5+δ, SmBSCF) exhibiting very good stability under water vapor- and carbon dioxide-containing atmosphere.
The maximal power density of the Ni–BaCe0.8 Zr0.1Y0.1O3-δ (Ni-BCZY81)/BCZY81/SmBSCF cell corresponds to 0.58 W cm−2 at 600 °C in fuel cell mode and a current density of j = 0.8 A cm−2 is measured at 1.3 V and 600 °C in electrolysis mode. The results were collected over a total working time of 280 h. The cell was stressed with several complete shutdowns and restarting protocols exhibiting an overall remarkable reversibility and durability.
•High performing reversible PCC cell prepared by tape casting and WPS.•Maximum Power Density of 580 mW/cm2, current density 800 mA/cm2 at 1.3 V at 600 °C.•First startup/shutdown test on PCC.•Activation protocol boosts performances by reactivating the cell at every restart.•SmBSCF shows excellent performances in PCFC and PCEC mode.
Display omitted
•Copper-based perovskite quantum dots are self-assembled during fiberized process.•Transition between Cs3Cu2I5 and CsCu2I3 dominates the luminescent color conversion.•Humidity is ...identified as a novel stimulus for luminescence regulation.•Polymer coating makes flexible fibers graphically displayable and chemically stable.•Water-responsive fluorescent fiber with unique incomplete reversibility is provided.
Halide perovskite presents great competitive advantages in the new generation of stimuli-responsive materials, while the tuning of fluorescence emission is still limited by irritative factors and external conditions. Herein, anti-solvent assisted crystallization and in-situ synthesis are innovatively combined to accomplish the fiberized self-assembly of copper-based perovskite quantum dots economically and environmentally, which makes humidity a novel stimulus for luminescence regulation. Under the excitation of medium-wave UV, the original Cs3Cu2I5-CsCu2I3@polyacrylonitrile (CCI@PAN) fibers exhibit a main emission peak of 460 nm with a shoulder at 550 nm, and the intensity of shoulder peak is gradually increased with the continuous addition of moisture. Switching from blue to yellow fluorescence is achieved in CCI@PAN fiber membrane by the introduction of water, which is attributed to the ultra-high solubility of CsI in water. Moreover, owing to the spatial limitation of the nanofibers, the unique incomplete reversibility exhibited by the nanofiber membrane during water removal predicts that the nanofiber membrane can be used as a permanent recording material. Overall, this work deeply explores the influence of humidity on the fluorescence and structure of perovskite quantum dots, providing a method to synthesize innovative perovskite nanofiber composites based on emission conversion, which has broad prospects in advanced anti-counterfeiting, biological protection display, information encryption and smart wearable devices.
Although the layered Ni-rich LiNixCoyMn1-x-yO2 (0.7 < x < 1, 0 < y < 0.3) cathode materials are expected to deliver high capacity, their moderate cycle lifetime and thermal stability still hinder ...practical applications. There's often a tradeoff between high capacity and structure stability since more Li+ ions delithiated during charging will leave the structure of the layered Ni-rich materials more vulnerable. Herein, we propose that improving the reversibility of H2-H3 phase transition for Ni-rich materials is effective to tackle this challenge. It has been confirmed that the generation of microcracks and structural transformations have been suppressed since the H2-H3 phase transition becomes reversible, while which shows little effect on capacity delivery. Consequently, using Ni-rich LiNi0.9Co0.1O2 as the cathode material, the 100th capacity retention cycling at 38 mA g−1 has been improved remarkably from 69.7% to 97.9% by adopting this strategy. Hence, it should be a novel solution to realize both high capacity and stable cyclability for the Ni-rich cathodes.
This work proposed a new way, i.e. pre-fabricating the surface of Ni-rich cathode with a cation-mixing layer through surface Ti-doping, to improve the reversibility of H2-H3 phase transition during the long cycles. The repeated formation of H3 phase in every charge-discharge process can afford the high capacity delivery, while the lossless H3 phase guarantees superior cycling stability. We consider this as a new idea to realize both high capacity and stability for Ni-rich cathodes. Display omitted
•A surface nanoscaled cation-mixing layer is fabricated for Ni-rich material through appropriate surficial Ti4+ substitution.•This preformed cation-mixing layer can improve the reversibility of H2-H3 phase transition.•Reversible H2-H3 phase transition contributes to realize both high capacity and stable cyclability for the Ni-rich cathodes.
Abundant Co-Nx sites are obtained by using zinc as a sacrificial agent, which act as bifunctional electrocatalytic sites for the reversible deposition and dissolution of Li2S.
Display omitted
...•Abundant Co-Nx sites were obtained by pyrolyzing Zn/Co bimetallic zeolitic imidazolate frameworks.•Zn as sacrificial agent to realize a homogenous distribution Co-Nx sites.•Co-Nx sites have a bifunctional catalytic effect towards Li2S deposition and dissolution.•Gibbs free energy of LiPSs conversion was reduced by Co-Nx sites.•The resultant LSB delivers an excellent capacity and stability at high rates.
Lithium sulfur battery (LSB) is promising next-generation energy storage system due to its high theoretical energy density and low cost. However, the poor reaction reversibility weakened its application. Here, a bifunctional electrocatalyst with highly active Co-Nx sites was synthesized by pyrolyzing Co/Zn bimetallic zeolitic imidazolate frameworks and used as separator coating layer to improve the reversibility of LSB. Using zinc as sacrificial template, the severe agglomeration of cobalt is effectively avoided, and abundant Co-Nx active sites are obtained. Investigations in reaction kinetic reveal that Co-Nx sites have a bifunctional electrocatalytic activity towards Li2S deposition and dissolution during cycling. Density functional theory calculations further confirm the strong electrocatalytic effect of Co-Nx sites, which results in a reduced Gibbs free energy for the liquid-solid reactions of lithium polysulfides to Li2S. Under the same experimental condition, the introduction of Co-Nx bitunctional electrocatalyst contributed to a 31% reversible capacity increase for LSB, with a capacity of 896 mAh g−1 at 1 C, and a slow capacity decay rate of 0.033% per cycle over 1000 cycles. Even for thick electrode with a sulfur loading of 6 mg cm−2, a reversible capacity of 4.2 mAh cm−2 can still be obtained at 0.2 C over 100 cycles.
PDF
