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A novel iron-hydrogen battery system, whose Fe3+/Fe2+ cathode circumvents slowly dynamic oxygen reduction reaction and anode is fed with clean and cordial hydrogen, is systematically investigated. The maximum discharge power density of the iron-hydrogen battery reaches to 96.0 mW/cm2 under the room temperature. The capacity reaches to 17.2 Ah/L and the coulombic and energy efficiency are achieved to 99% and 86%, respectively, during the galvanostatic charge-discharge test. Moreover, stable cycling test is observed for more than 240 h and 100 cycles with the iron sulfate in the sulfuric acid solutions. It is found that air plasma treatment onto the cathode carbon paper can generate the oxygen-containing groups and increase the hydrophilic pores proportion to ca. 40%, enlarging nearly 6-fold effective diffusion coefficient and improving the mass transfer in the battery performance. The simple iron-hydrogen energy storage battery design offers us a new strategy for the large-scale energy storage and hydrogen involved economy.

The ordered membrane electrode assembly (MEA) is currently the frontier research field of proton exchange membrane fuel cells (PEMFCs). The ordered MEA is effective in increasing the utilization of...

It is very challenging to develop luminescent detection methods for iodide ions due to their significant fluorescence quenching of general fluorophores induced by the heavy-atom effect. Herein, we reveal a unique crystallization-induced bright phosphorescence of tetraphenylphosphonium iodide (TPP I) and develop a novel time-gated detection method for iodide ions to minimize the autofluorescence from complex biological samples. Both the involvement of heavy iodide ion and accessible ionic interaction-induced organic crystals contribute to the accomplishment of a very high phosphorescence quantum yield (0.42) for TPP I. This specific iodide-triggered bright organic phosphorescence enables the development of a novel time-gated detection method for iodide ions in the luminescence turn-on manner and further offers an opportunity to establish a facile test strip for the visual detection of iodide ions based on solid-state phosphorescence on a solid substrate. Excellent performance of this probe in imaging iodide in live cells and intriguing use in double encryption illustrate the versatile and broad application prospects of highly efficient organic ionic crystals in various areas.

Butyrylcholinesterase (BChE) generally acts as an important plasma biomarker for clinical diagnosis due to its major contribution to human plasma cholinesterase levels, but its current fluorometric assay relying on fluorogenic substrates frequently suffers from the lack of sufficiently fast response time and specific recognition of substrates relative to the traditional Ellman's method. In this work, we report a fluorescent molecular probe for assaying BChE activity based on thiol-triggered fluorescence enhancement via thiol-ene click reactions. A low-temperature experiment and theoretical analysis exclude the possibility of weak fluorescence of the probe caused by an intramolecular photoinduced electron transfer process and support the main cause of an ultraslow radiative rate due to the introduction of two acrylyl groups. This probe has sensitive fluorescence responses to thiols via thiol-ene click chemistry, and it can distinguish between glutathione and cysteine or homocysteine in different emission colors. The rapid reaction kinetics of this probe enables it to monitor hydrolysis reactions catalyzed by butyrylcholinesterase (BChE) in a real-time manner. This probe is used to develop the first fluorometric assay of BChE activity based on fluorescence enhancement triggered by thiol-ene click chemistry using butyrylthiocholine as the substrate. The established BChE assay shows excellent sensitivity, and is capable of avoiding the interference from glutathione and acetylcholinesterase (AChE) in a complex matrix. The inhibition test of tacrine on BChE with this assay substantiates its feasibility in screening potential inhibitors of BChE. This work demonstrates a design strategy of fluorescent probes lighted up by thiol-ene click reactions, reveals the main cause of thiol-triggered fluorescence enhancement by altering the radiative rate, and provides the first fluorometric assay of BChE based on rapid thiol-ene click reactions.

Distinctive aggregation-induced emission (AIE) phenomenon of thiolate-protected silver nanoclusters (AgNCs) has been revealed; these AgNCs have shown great potential for exploitation and utilization, but their applications as a bright luminogen in the chemosensing and bioimaging areas are greatly limited by their ultralow brightness in an aqueous solution. Herein, we report facile fabrication of hydrophobicity-guided self-assembled particles of silver nanoclusters with aggregation-induced emission. A hydrophobic ligand, thiosalicylic acid, was adopted to prepare AgNCs via a one-step way, and thiosalicylic acid-capped AgNCs showed significant AIE behavior. This AIE property of AgNCs enables them to selectively respond to multiple external stimuli such as solvent polarity, pH and environmental temperature. The hydrophobic nature of thiosalicylic acid as capping ligands of AgNCs drives a self-assembly process of AgNCs in an aqueous solution that results in the formation of self-assembled particles of AgNCs with bright luminescence. Sensitive detection of mercuric ion based on the highly luminescent AgNC AIE particles was achieved in terms of a strong quenching effect of mercuric ion. Cellular viability and luminescence imaging performance of the AgNC AIE particles on living cells were also evaluated for the first time. This study demonstrates the fabrication of AIE particles of silver nanoclusters with bright luminescence guided by hydrophobic interaction and reveals excellent bioimaging performance of AIE particles in living cells.

Copper nanoclusters have shown tremendous application perspective because of their outstanding luminescence properties, inherent biocompatibility, and easy accessibility; however, low emission brightness and poor resistance to ambient oxygen greatly limit their wide applications in long-term sensing and bioimaging. Herein, we develop an effective and general approach to enhancing the luminescence and stability of copper nanoclusters through in situ generation of a silica shell and further propose a versatile surface functionalization method to achieve functional copper nanoclusters via the formation of a second layer of a silica shell. The use of thiol-containing trialkoxysilane facilitates in situ generation of a silica shell on the surface of copper nanoclusters, and the existence of the first layer of a silica shell substantially improves the emission efficacy of copper nanoclusters. The introduction of a second layer of a silica shell not only greatly enhances the brightness and stability of copper na...

Manipulation of the emission properties of pure organic molecules through external stimuli is attractive but challenging. Herein, a dual-emissive hexathiobenzene-based molecule is reported with significant aggregation-induced phosphorescence characteristics, and demonstrates reversible switching among blue, green, and yellow phosphorescence by controlling molecular aggregation state or protonation state. Variation of solvent or pH value manipulates the interconversion between fluorescence and phosphorescence, while the change in protonation state in organic solvent switches two short-lived emissions in a controllable manner. Such a controlled manipulation is achieved by the rational design of combining a twisted structure and the proper arrangement of energy gaps among different excited states. This work provides a new design principle for organic molecules with efficient room-temperature phosphorescence and tunable singlet-triplet emissive properties, and contributes to the design and development of smart materials and intelligent optoelectronic devices.

Acetylcholinesterase (AChE) is an important biomarker of many neurotransmitter-associated diseases and can be used to screen potential drugs and diagnose poisoning by chemical warfare agents and pesticides, and thus the accurate detection of AChE is of great practical significance. In this work, thiol-triggered disaggregation-induced emission through competitive interaction among 3,4,9,10-perylenetetracarboxylic acid (PTCA), copper ion and glutathione is identified, and a reliable fluorometric assay for acetylcholinesterase (AChE) activity is developed on the basis of this molecular switch. It is found that PTCA in neutral and alkaline solution exhibits very bright green fluorescence, and its quantum yield is up to 78% in alkaline solution. The presence of Cu2+ leads to the formation of PTCA/Cu(II) nanoaggregates and the quenching of the fluorescence, but the fluorescence can be fully switched on after the introduction of equivalent amount of thiol-containing compounds such as glutathione. A reversible fluorescence switch can be run in this way by the alternative introduction of Cu2+ and GSH. This switch enables the detection of AChE in the signal turn-on mode when acetylthiocholine is used as the substrate. Quantitative measurement of AChE level with detection limit as low as 4 U/L and a broad linear scope ranging from 15 to 500.0 U/L is achieved based on the developed assay. The inhibitor screening function was also assessed using tacrine as the example, and the assay performs well in the screening tacrine. This work proposed thiol-triggered disaggregation-induced emission mediated by competitive interaction, and provides a sensitive detection method for AChE level and its inhibitor screening.

Manipulation of photophysical properties of pure organic materials via simple alteration is attractive but extremely challenging because of the lack of valid design strategies for achieving ultralong afterglow or efficient room-temperature phosphorescence. Herein, we report a first photophysical manipulation of organic ionic crystals from ultralong afterglow to highly efficient phosphorescence by variation of halides in the crystals. Crystal structural analysis reveals ultralong organic afterglow of tetraphenylphosphonium chloride is promoted by strong intermolecular electronic coupling in the crystal, and theoretical analysis demonstrates that the tremendous boost of the phosphorescence of tetraphenylphosphonium iodide is caused by the coupling effects of significant heavy atom effect from iodine atoms and a small energy difference between the first singlet and triplet states. This work contributes to regulating long-lived emissive behaviors of pure organic ionic crystals in a controlled way and will promote the development of optical switches controlled by external stimuli.

Butyrylcholinesterase (BChE) mainly contributing to plasma cholinesterase activity is an important indicator for routinely diagnosing liver function and organophosphorus poisoning in clinical diagnosis, but its current assays are scarce and frequently suffer from some significant interference and instability. Herein, we report a redox-controlled fluorescence nanoswtich based on reversible disulfide bonds, and further develop a fluorometric assay of BChE via thiol-triggered disaggregation-induced emission. Thiol-functionalized carbon quantum dots (thiol-CQDs) with intense fluorescence is found to be responsive to hydrogen peroxide, and their redox reaction transforms thiol-CQDs to nonfluorescent thiol-CQD assembly. The thiols inverse this process by a thiol-exchange reaction to turn on the fluorescence. The fluorescence can be reversibly switched by the formation and breaking of disulfide bonds caused by external redox stimuli. The specific thiol-triggered disaggregation-induced emission enables us to assay BChE activity in a fluorescence turn-on and real-time way using butyrylthiocholine iodide as the substrate. As-established BChE assay achieves sufficient sensitivity for practical determination in human serum, and is capable of avoiding the interference from micromolar glutathione and discriminatively quantifying BChE from its sister enzyme acetylcholinesterase. The first design of reversible redox-controlled nanosiwtch based on disulfide expands the application of disulfide chemistry in sensing and clinical diagnostics, and this novel BChE assay enriches the detection methods for cholinesterase activity.