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Room-temperature phosphorescence (RTP) of purely organic materials is easily quenched with unexpected purposes because the excited triplet state is extremely susceptible to external stimuli. How to stabilize the RTP property of purely organic luminogens is still challenging and considered as the bottleneck in the further advancement of the bottom-up approach. Here, we describe a gated strategy that can effectively harness RTP by employing complexation/dissociation with proton. Due to the order-disorder transition orientation of intermolecular packing, the RTP of triazine derivative Br-TRZ will easily vanish upon mechanical force. Impressively, by enhancing its intramolecular charge transfer effect, the protonated Br-TRZ stubbornly possesses an obvious RTP under external grinding, whatever in the ordered or disordered intermolecular arrangement state. Consequently, the “Lock” gate of RTP was achieved in the protonated Br-TRZ molecule. Combined with theoretical calculation analysis, the enhanced charge transfer effect can narrow the singlet−triplet energy gap significantly, and stabilize the RTP property of triazine derivative sequentially. Furthermore, the locked RTP can be tuned via proton and counterions repeatedly and show excellent reversibility. This gated RTP concept provide an effective strategy for stabilizing the RTP emission of purely organic systems.

High-temperature proton exchange membrane fuel cells (HT-PEMFCs) bring new opportunities for portable power generation due to their outstanding advantages such as high tolerance to fuel/air impurities and simplified heat/water management. However, carbon-supported nanostructured Pt-based catalysts running at temperatures over 150°C are challenged by the severe aggregation and carbon corrosion, thus leading to poor durability. Herein, we demonstrate that dendritic Pt-Ni nanoparticles supported on fluorinated carbon black (white carbon black) could significantly enhance the performance and durability of HT-PEMFCs as the cathode catalysts running at 160°C due to the strong interaction of the F and Ni atoms to form a NixFy interface on Pt-Ni nanoparticles. With the formation of a stable NixFy interface, this integrated HT-PEMFC reached peak power densities of 906 mW cm−2 and demonstrated excellent durability at 160°C under anhydrous H2/O2 conditions. This mitigation strategy was applied to Pt-alloy/C electrocatalysts and resulted in the elimination of Pt dissolution in practical fuel cells.

Polymeric carbon nitride (PCN) is an important metal-free photocatalyst for visible light-driven hydrogen peroxide (H

High-entropy oxides (HEOs), a new concept of entropy stabilization, exhibit unique structures and fascinating properties, and are thus important class of materials with significant technological potential. However, the conventional high-temperature synthesis techniques tend to afford micron-scale HEOs with low surface area, and the catalytic activity of available HEOs is still far from satisfactory because of their limited exposed active sites and poor intrinsic activity. Here we report a low-temperature plasma strategy for preparing defect-rich HEOs nanosheets with high surface area, and for the first time employ them for 5-hydroxymethylfurfural (HMF) electrooxidation. Owing to the nanosheets structure, abundant oxygen vacancies, and high surface area, the quinary (FeCrCoNiCu)3 O4 nanosheets deliver improved activity for HMF oxidation with lower onset potential and faster kinetics, outperforming that of HEOs prepared by high-temperature method. Our method opens new opportunities for synthesizing nanostructured HEOs with great potential applications.

High-entropy alloys (HEAs) have been widely studied due to their unconventional compositions and unique physicochemical properties for various applications. Herein, for the first time, we propose a surface strain strategy to tune the electrocatalytic activity of HEAs for methanol oxidation reaction (MOR). High-resolution aberration-corrected scanning transmission electron microscopy (STEM) and elemental mapping demonstrate both uniform atomic dispersion and the formation of a face-centered cubic (FCC) crystalline structure in PtFeCoNiCu HEAs. The HEAs obtained by heat treatment at 700°C (HEA-700) exhibit 0.94% compressive strain compared with that obtained at 400°C (HEA-400). As expected, the specific activity and mass activity of HEA-700 is higher than that of HEA-400 and most of the state-of-the-art catalysts. The enhanced MOR activity can be attributed to a shorter Pt-Pt bond distance in HEA-700 resulting from compressive strain. The nonprecious metal atoms in the core could generate compressive strain and down shift d-band centers via electron transfer to surface Pt layer. This work presents a new perspective for the design of high-performance HEAs electrocatalysts.

Integrating biomass upgrading and hydrogen production in an electrocatalytic system is attractive both environmentally and in terms of sustainability. Conventional electrolyser systems coupling anodic biosubstrate electrooxidation with hydrogen evolution reaction usually require electricity input. Herein, we describe the development of an electrocatalytic system for simultaneous biomass upgrading, hydrogen production, and electricity generation. In contrast to conventional furfural electrooxidation, the employed low-potential furfural oxidation enabled the hydrogen atom of the aldehyde group to be released as gaseous hydrogen at the anode at a low potential of approximately 0 V

An ultra-thin carbon nitride with loose structure and more carbon defects on the surface was achieved through high-temperature peeling methods. Its composition, morphological characteristics, surface defect types and electrochemical properties have been measured. After atomic scale structure control and surface defects construction, the photocatalytic activity of prepared g-C3N4-V for ammonia conversion from dinitrogen can be greatly improved in contrast with bulk g-C3N4. Under visible light irradiation, the defective g-C3N4-V can produce 54 µmol/L NH3 within 100 min without any cocatalyst and sacrificial agent. The relationship between morphology characteristics and activity of defective ultrathin g-C3N4 materials was analyzed in detail. Benefiting from thin layer structure and more surface carbon vacancies, the effective charge separation from both bulk and surface can be achieved. Notably, the engineered carbon vacancies greatly facilitate the adsorption and activation of dinitrogen molecule, extremely improving the nitrogen fixation activity for the defective ultrathin g-C3N4-V materials. This work affords novel insights into the design of photocatalyst with defective ultrathin structure towards nitrogen fixation.

Dissolved oxygen (DO) plays a crucial role in environment, food processing, and biotechnology. Although several physical-doping DO probes have been developed, a sensitive and reliable sensor for re...

Analyses of the physiology and pathology of active biochemical species in their native contexts are critical for early diagnosis and therapy. Optical imaging has emerged as one of the promising modalities for noninvasive and real-time visualization of important biomolecules or biological events, and it has witnessed major advances in the field of imaging in vitro and in vivo . In this review, we present a survey of common approaches and tactics for enhanced targetability, response rate, and photostability in bioimaging applications. Recently developed and representative examples are illustrated on the cellular and tissue levels.

Solar-driven reduction of CO2 , which converts inexhaustible solar energy into value-added fuels, has been recognized as a promising sustainable energy conversion technology. However, the overall conversion efficiency is significantly limited by the inefficient charge separation and sluggish interfacial reaction dynamics, which resulted from a lack of sufficient active sites. Herein, Bi12 O17 Cl2 superfine nanotubes with a bilayer thickness of the tube wall are designed to achieve structural distortion for the creation of surface oxygen defects, thus accelerating the carrier migration and facilitating CO2 activation. Without cocatalyst and sacrificing reagent, Bi12 O17 Cl2 nanotubes deliver high selectivity CO evolution rate of 48.6 μmol g-1 h-1 in water (16.8 times than of bulk Bi12 O17 Cl2 ), while maintaining stability even after 12 h of testing. This paves the way to design efficient photocatalysts with collaborative optimizing charge separation and CO2 activation towards CO2 photoreduction.

In this study, S, N codoped graphene quantum dots/(BiO)2CO3 hollow microspheres have been fabricated by a facile electrostatic self-assembly method. The nanosized S, N:GQDs, which can be obtained b...

Aggregation-induced emission (AIE) imaging probes have recently received considerable attention because of their unique property of high performance in the aggregated state and their imaging capability. However, the tendency of AIE molecules to aggregate into micron long irregular shapes, which significantly limits their application in vivo, is becoming a serious issue that needs to be addressed. Here, we introduce a novel engineering strategy to tune the morphology and size of AIE nanoaggregates, based on flash nanoprecipitation (FNP). Quinolinemalononitrile (ED) is encapsulated inside properly selected amphiphilic block copolymers of varying concentration. This leads to a variety of ED particle morphologies with different sizes. The shape and size are found to have strong influences on tumor targeting both in vitro and in vivo. The current results therefore indicate that the FNP method together with optimal choice of an amphiphilic copolymer is a universal method to systematically control the aggregation state of AIE materials and hence tune the morphology and size of AIE nanoaggregates, which is potentially useful for precise imaging at specific tumor sites.

Theranostic prodrug therapy enables the targeted delivery of anticancer drugs with minimized adverse effects and real-time in situ monitoring of activation of the prodrugs. In this work, we report the synthesis and biological assessment of the near-infrared (NIR) prodrug DCM-S-PPT and its amphiphilic copolymer (mPEG-DSPE)-encapsulated nanoparticles. DCM-S-PPT is composed of podophyllotoxin (PPT) as the anticancer moiety and a dicyanomethylene-4H-pyran (DCM) derivative as the NIR fluorescent reporter, which are linked by a thiol-specific cleavable disulfide bond. In vitro experiments indicated that DCM-S-PPT has low cytotoxicity and that glutathione (GSH) can activate DCM-S-PPT resulting in PPT release and a concomitant significant enhancement in NIR fluorescence at 665 nm. After being intravenously injected into tumor-bearing nude mice, DCM-S-PPT exhibited excellent tumor-activated performance. Furthermore, we have demonstrated that mPEG-DSPE as a nanocarrier loaded with DCM-S-PPT (mPEG-DSPE/DCM-S-PPT) showed even greater tumor-targeting performance than DCM-S-PPT on account of the enhanced permeability and retention effect. Its tumor-targeting ability and specific drug release in tumors make DCM-S-PPT a promising prodrug that could provide a significant strategy for theranostic drug delivery systems.

An ultra-thin carbon nitride with loose structure and more carbon defects on the surface was achieved through high-temperature peeling methods. Its composition, morphological characteristics, surface defect types and electrochemical properties have been measured. After atomic scale structure control and surface defects construction, the photocatalytic activity of prepared g-C

Photocatalytic solar energy conversion is a clean technology for producing renewable energy sources, but its efficiency is greatly hindered by the kinetically sluggish oxygen evolution reaction. Herein, confined defects in atomically-thin BiOCl nanosheets were created to serve as a remarkable platform to explore the relationship between defects and photocatalytic activity. Surface defects can be clearly observed on atomically-thin BiOCl nanosheets from scanning transmission electron microscopy images. Theoretical/experimental results suggest that defect engineering increased states of density and narrowed the band gap. With combined effects from defect induced shortened hole migratory paths and creation of coordination-unsaturated active atoms with dangling bonds, defect-rich BiOCl nanosheets displayed 3 and 8 times higher photocatalytic activity towards oxygen evolution compared with atomically-thin BiOCl nanosheets and bulk BiOCl, respectively. This successful application of defect engineering will pave a new pathway for improving photocatalytic oxygen evolution activity of other materials.

Photocatalytic CO2 reduction suffers from the weakness of high energy barrier, low efficiency and poor selectivity. Exploring effective strategy to enhance the adsorption and activation behavior of CO2 molecules is an alternative approach to boost CO2 photoreduction performance. In this work, abundant oxygen vacancies (VO) are introduced onto Bi2Sn2O7 nanoparticles (NPs) by decreasing their size down to about 4 nm. The VO mediated NPs exhibit a tremendous 8.1 times enhanced performance than the bulk counterpart towards CO2-to−CO conversion in pure water. This is attributed to fast charge diffusion and abundant Vo for effective CO2 adsorption and activation in the ultra-small nanoparticles. The VO mediated Bi2Sn2O7 NPs have electron back donation nature and optimized electronic structure for effectively activating CO2, which were demonstrated by density functional theory calculations. During the reduction process, the Vo can effeciently stabilize the COOH* intermediates, and also lower the energy barrier of CO desorption determining step.

Development of fluorescent probes that can monitor foodstuff hazards is highly desirable. Herein we report the first example of an AIEgen probe (QM-TPA), conjugated by a quinoline-malononitrile (QM) scaffold and triphenylamine unit, for direct sensing of triacylglycerol polymers in frying oil, enabling a rapid probing, on-site analysis, and portable operation in food inspection applications.

We describe an enzyme-regulated liberation strategy to in situ generate AIEgen nanoaggregates for on-site sensing and long-term tracking of β-galactosidase in ovarian cancer cells., Development of fluorescent probes for on-site sensing and long-term tracking of specific biomarkers is particularly desirable for the early detection of diseases. However, available small-molecule probes tend to facilely diffuse across the cell membrane or remain at the activation site but always suffer from the aggregation-caused quenching (ACQ) effect. Here we report an enzyme-activatable aggregation-induced emission (AIE) probe QM–βgal, which is composed of a hydrophilic β-galactosidase (β-gal)-triggered galactose moiety and a hydrophobic AIE-active fluorophore QM–OH. The probe is virtually non-emissive in aqueous media, but when activated by β-gal, specific enzymatic turnover would liberate hydrophobic AIE luminogen (AIEgen) QM–OH, and then highly fluorescent nanoaggregates are in situ generated as a result of the AIE process, allowing for on-site sensing of endogenous β-gal activity in living cells. Notably, taking advantage of the improved intracellular retention of nanoaggregates, we further exemplify QM–βgal for long-term (∼12 h) visualization of β-gal-overexpressing ovarian cancer cells with high fidelity, which is essential for biomedicine and diagnostics. Thus, this enzyme-activatable AIE probe not only is a potent tool for elucidating the roles of β-gal in biological systems, but also offers an enzyme-regulated liberation strategy to exploit multifunctional probes for preclinical applications.

Flash nanoprecipitation (FNP) is an easily scalable and fast processing method for the preparation of nanoparticles (NPs) with simple vortex equipment. By using the FNP method, fluorescent NPs are prepared in less than 1 s in a multi-inlet vortex mixer, in which hydrophobic aggregation-induced emission (AIE)-active dye of EDP is incorporated within the biocompatible block copolymer poly(ethylene glycol)-b-poly(e-caprolactone) for EDP NP assembly. The formulation parameters of stream velocity, dyes, and loading and concentration in FNP are optimized. The sizes of the NPs ranged from 20 to 60 nm with a ratio change of mixed solvents. As a control, an aggregation-caused quenching (ACQ) molecule of BDP was also synthesized for BDP NPs. To gain insight into the effect of the polymer on the aggregation state of hydrophobic dyes, the preparation of EDP and BDP NPs without block copolymer was also investigated. Apparently, the sizes of the NPs display large distributions without an amphiphilic block copolymer as ...

In this paper, bismuth oxybromide (BiOBr) nanosquares photocatalysts were synthesized via a facile hydrothermal method with the double regulation of the ionic liquid (IL) 1-hexadecyl-3-methylimidazolium bromide and ammonium bismuth citrate (BCA). To the best of our knowledge, this report is the first to describe the BiOBr material with simultaneous bismuth and halogen bidirectional source regulation. The structures, components, morphologies, optical properties and photocatalytic properties of the as-prepared samples were specifically explored. The photocatalytic ability was assessed using the degradation of rhodamine B under visible light irradiation. The BiOBr-IL+BCA exhibited improved photocatalytic activity compared with the BiOBr materials without double regulation. The primary active species were determined to be holes (h+) and superoxide radicals (O2-) using electron spin resonance (ESR) analysis and free radical trapping experiments. This enhanced activity was attributed to its larger specific surface, the superior electron transfer ability, and the increased negative conduction band position, which favors the photogenerated electrons to trap the molecular oxygen to produce O2-. The production of more O2- can benefit the removal of pollutants.

Leucine aminopeptidase (LAP), one of the important proteolytic enzymes, is intertwined with the progress of many pathological disorders as a well-defined biomarker. To explore fluorescent aminopeptidase probe for quantitative detection of LAP distribution and dynamic changes, herein we report a LAP-targeting near-infrared (NIR) fluorescent probe (DCM-Leu) for ratiometric quantitative trapping of LAP activity in different kinds of living cells. DCM-Leu is composed of a NIR-emitting fluorophore (DCM) as a reporter and l-leucine as a triggered moiety, which are linked together by an amide bond specific for LAP cleavage. High contrast on the ratiometric NIR fluorescence signal can be achieved in response to LAP activity, thus enabling quantification of endogenous LAP with "build-in calibration" as well as minimal background interference. Its ratiometric NIR signal can be blocked in a dose-dependent manner by bestatin, an LAP inhibitor, indicating that the alteration of endogenous LAP activity results in these obviously fluorescent signal responses. It is worth noting that DCM-Leu features striking characteristics such as a large Stokes shift (∼205 nm), superior selectivity, and strong photostability responding to LAP. Impressively, not only did we successfully exemplify DCM-Leu in situ ratiometric trapping and quantification of endogenous LAP activity in various types of living cells, but also, with the aid of three-dimensional confocal imaging, the intracellular LAP distribution is clearly observed from different perspectives for the first time, owing to the high signal-to-noise of ratiometric NIR fluorescent response. Collectively, these results demonstrate preclinical potential value of DCM-Leu serving as a useful NIR fluorescent probe for early detection of LAP-associated disease and screening inhibitor.

Development of "smart" noninvasive bioimaging probes for trapping specific enzyme activities is highly desirable for cancer therapy in vivo. Given that β-galactosidase (β-gal) is an important biomarker for cell senescence and primary ovarian cancers, we design an enzyme-activatable ratiometric near-infrared (NIR) probe (DCM-βgal) for the real-time fluorescent quantification and trapping of β-gal activity in vivo and in situ. DCM-βgal manifests significantly ratiometric and turn-on NIR fluorescent signals simultaneously in response to β-gal concentration, which makes it favorable for monitoring dynamic β-gal activity in vivo with self-calibration in fluorescent mode. We exemplify DCM-βgal for the ratiometric tracking of endogenously overexpressed β-gal distribution in living 293T cells via the lacZ gene transfection method and OVCAR-3 cells, and further realize real-time in vivo bioimaging of β-gal activity in colorectal tumor-bearing nude mice. Advantages of our system include light-up ratiometric NIR fluorescence with large Stokes shift, high photostability, and pH independency under the physiological range, allowing for the in vivo real-time evaluation of β-gal activity at the tumor site with high-resolution three-dimensional bioimaging for the first time. Our work provides a potential tool for in vivo real-time tracking enzyme activity in preclinical applications.