Conjugated Polyelectrolyte and Aptamer Based Potassium Assay via Single‐ and Two‐Step Fluorescence Energy Transfer with a Tunable Dynamic Detection Range

A new potassium ion detection assay was developed using a dye‐labeled aptamer and conjugated polyelectrolyte (CPE) as a signaling platform via 1‐step and 2‐step fluorescence resonance energy transfer. Guanine‐rich K⁺‐specific aptamers were designed as K⁺ ion recognition species with 6‐carboxyfluorescein (6‐FAM) and 6‐carboxytetramethylrhodamine (6‐TAMRA) at both termini. In the presence of K⁺ ions, the aptamers undergo a conformational change from an unfolded to folded form by forming a G‐quadruplex with K⁺, bringing two dyes in proximity. FRET‐induced 6‐TAMRA emission was proportional to [K⁺] in a range of 22.5 μm –100 mm in water without interference by the presence of excess Na⁺ ions (100 mm ). Upon the addition of CPE, a two‐step FRET process from CPE to 6‐TAMRA via 6‐FAM was enabled, showing an intensified 6‐TAMRA signal with K⁺ ions. The dynamic detection range and limit of detection (LOD) was fine‐tuned from ～millimolar to ～nanomolar concentrations of K⁺ by modulating the signal amplification effect of CPE. The LOD was determined to be ≈3.0 nm . This detection assay also showed high selectivity against other metal ions. This sensing scheme can be extended to the detection of a wide range of target materials by simply modifying the recognition aptamer sequence.     

3D Carbon Nanotube Network Bridged Hetero‐Structured Ni‐Fe‐S Nanocubes toward High‐Performance Lithium,Sodium, and Potassium Storage

Lithium‐ion, sodium‐ion, and potassium‐ion batteries have captured tremendous attention in power supplies for various electric vehicles and portable electronic devices. However, their practical applications are severely limited by factors such as poor rate capability, fast capacity decay, sluggish charge storage dynamics, and low reversibility. Herein, hetero‐structured bimetallic sulfide (NiS/FeS) encapsulated in N‐doped porous carbon cubes interconnected with CNTs (Ni‐Fe‐S‐CNT) are prepared through a convenient co‐precipitation and post‐heat treatment sulfurization technique of the corresponding Prussian‐blue analogue nanocage precursor. This special 3D hierarchical structure can offer a stable interconnect and conductive network and shorten the diffusion path of ions, thereby greatly enhancing the mobility efficiency of alkali (Li, Na, K) ions in electrode materials. The Ni‐Fe‐S‐CNT nanocomposite maintains a charge capacity of 1535 mAh g^?1 at 0.2 A g^?1 for lithium ion batteries, 431 mAh g^?1 at 0.1 A g^?1 for sodium ion batteries, and 181 mAh g^?1 at 0.1 A g^?1 for potassium‐ion batteries, respectively. The high performance is mainly attributed to the 3D hierarchically high‐conductivity network architecture, in which the hetero‐structured FeS/NiS nanocubes provide fast Li⁺/Na⁺/K⁺ insertion/extraction and reduced ion diffusion paths, and the distinctive 3D networks maintain the electrical contact and guarantee the structural integrity.     

Controlled Design of Well‐Dispersed Ultrathin MoS2 Nanosheets inside Hollow Carbon Skeleton: Toward Fast Potassium Storage by Constructing Spacious “Houses” for K Ions

The large volume expansion induced by K⁺ intercalation is always a big challenge for designing high‐performance electrode materials in potassium‐ion storage system. Based on the idea that large‐sized ions should accommodate big “houses,” a facile‐induced growth strategy is proposed to achieve the self‐loading of MoS₂ clusters inside a hollow tubular carbon skeleton (HTCS). Meantime, a step‐by‐step intercalation technology is employed to tune the interlayer distance and the layer number of MoS₂. Based on the above, the ED‐MoS₂@CT hybrids are achieved by self‐loading and anchoring the well‐dispersed ultrathin MoS₂ nanosheets on the inner surface of HTCSs. This unique compositing model not only alleviates the mechanical strain efficiently, but also provides spacious “roads” (hollow tubular carbon skeleton) and “houses” (interlayer expanded ultrathin MoS₂ sheets) for fast K⁺ transition and storage. As an anode of potassium‐ion batteries, the resultant ED‐MoS₂@CT electrode delivers a high specific capacity of 148.5 mAh g^?1 at 2 A g^?1 after 10 000 cycles with only 0.002% fading per cycle. The assembled ED‐MoS₂@CT//PC potassium‐ion hybrid supercapacitor device shows a high energy density of 148 Wh kg^?1 at a power density of 965 W kg^?1, which is comparable to that of lithium‐ion hybrid supercapacitors.     

Hierarchical NiS2 Modified with Bifunctional Carbon for Enhanced Potassium‐Ion Storage

Potassium‐ion batteries (PIBs) are currently drawing increased attention as a promising alternative to lithium‐ion batteries (LIBs) owing to the abundant resource and low cost of potassium. However, due to the large ionic radius size of K⁺, electrode material that can stably maintain K⁺ insertion/deintercalation is still extremely inadequate, especially for anode material with a satisfactory reversible capacity. As an attempt, nitrogen/carbon dual‐doped hierarchical NiS₂ is introduced as the electrode material in PIBs for the first time. Considering that the introduction of the carbon layer effectively alleviates the volume expansion of the material itself, further improves the electronic conductivity, and finally accelerates the charge transfer of K⁺, not surprisingly, NiS₂ decorated with the bifunctional carbon (NiS₂@C@C) material electrode shows excellent potassium storage performances. When utilized as a PIB anode, it delivers a high reversible capacity of 302.7 mAh g^?1 at 50 mA g^?1 after 100 cycles. The first coulombic efficiency is 78.6% and rate performance is 151.2 mAh g^?1 at 1.6 A g^?1 of the NiS₂@C@C, which are also notable. Given such remarkable electrochemical properties, this work is expected to provide more possibilities for the reasonable design of advanced electrode materials for metal sulfide potassium ion batteries.     

Microchannel‐Confined MXene Based Flexible Piezoresistive Multifunctional Micro‐Force Sensor

Multifunctional micro‐force sensing in one device is an urgent need for the higher integration of the smaller flexible electronic device toward wearable health‐monitoring equipment, intelligent robotics, and efficient human–machine interface. Herein, a novel microchannel‐confined MXene‐based flexible piezoresistive sensor is demonstrated to simultaneously achieve multi‐types micro‐force sensing of pressure, sound, and acceleration. Benefiting from the synergistically confined effect of the fingerprint‐microstructured channel and the accordion‐microstructured MXene materials, the as‐designed sensor remarkably endows a low detection limit of 9 Pa, a high sensitivity of 99.5 kPa^?1, and a fast response time of 4 ms, as well as non‐attenuating durability over 10 000 cycles. Moreover, the fabricated sensor is multifunctionally capable of sensing sounds, micromotion, and acceleration in one device. Evidently, such a multifunctional sensing characteristic can highlight the bright prospect of the microchannel‐confined MXene‐based micro‐force sensor for the higher integration of flexible electronics.     

Selective Zinc(II)‐Ion Fluorescence Sensing by a Functionalized Mesoporous Material Covalently Grafted with a Fluorescent Chromophore and Consequent Biological Applications

A highly ordered 2D‐hexagonal mesoporous silica material is functionalized with 3‐aminopropyltriethoxysilane. This organically modified mesoporous material is grafted with a dialdehyde fluorescent chromophore, 4‐methyl‐2,6‐diformyl phenol. Powder X‐ray diffraction, transmission electron microscopy, N₂ sorption, Fourier transform infrared spectroscopy, and UV‐visible absorption and emission have been employed to characterize the material. This material shows excellent selective Zn²⁺ sensing, which is due to the fluorophore moiety present at its surface. Fluorescence measurements reveal that the emission intensity of the Zn²⁺‐bound mesoporous material increases significantly upon addition of various concentrations of Zn²⁺, while the introduction of other biologically relevant (Ca²⁺, Mg²⁺, Na⁺, and K⁺) and environmentally hazardous transition‐metal ions results in either unchanged or weakened intensity. The enhancement of fluorescence is attributed to the strong covalent binding of Zn²⁺, evident from the large binding constant value (0.87 × 10⁴ M ^?1). Thus, this functionalized mesoporous material grafted with the fluorescent chromophore could monitor or recognize Zn²⁺ from a mixture of ions that contains Zn²⁺ even in trace amounts and can be considered as a selective fluorescent probe. We have examined the application of this mesoporous zinc(II) sensor to cultured living cells (A375 human melanoma and human cervical cancer cell, HeLa) by fluorescence microscopy.     

Synthesis of Potassium‐Modified Graphene and Its Application in Nitrite‐Selective Sensing

Chemical modification with foreign atoms is a leading strategy to intrinsically modify the properties of host materials. Among them, potassium (K) modification plays a critical role in adjusting the electronic properties of carbon materials. Graphene, a true 2D carbon material, has shown fascinating applications in electrochemical sensing and biosensing. In this work, a facile and mild strategy to K‐modifying in graphene at room‐temperature is reported for the first time. X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectra, and cyclic voltammetry are used to characterize this K‐modified graphene. The K‐modified graphene is capable of acting as an electron transfer medium and more efficiently promotes charge transfer than unmodified graphene. A highly sensitive and stable amperometric sensor based on its excellent electrocatalytic activity toward the oxidation of NO₂^? is proposed. The sensor shows a linear range from 0.5 μM to 7.8 mM with a detection limit of 0.2 μM at a signal‐to‐noise ratio of 3. The modified electrode has excellent analytical performance and can be successfully applied in the determination of NO₂^? released from liver cancer and leukemia cells and shows good application potential in biological systems.     

Gated Mesoporous SiO2 Nanoparticles Using K+‐Stabilized G‐Quadruplexes

The K⁺‐induced formation of G‐quadruplexes provides a versatile motif to lock or unlock substrates trapped in the pores of mesoporous SiO₂ nanoparticles, MP‐SiO₂ NPs. In one system, the substrate is locked in the MP‐SiO₂ NPs by K⁺‐ion‐stabilized G‐quadruplex units, and the pores are unlocked by the elimination of K⁺ ions using Kryptofix [2.2.2] (KP) or 18‐crown‐6‐ether (CE) from the G‐quadruplexes. In the second system, the substrate is locked in the pores by means of K⁺‐stabilized aptameric G‐quadruplex/thrombin units. Unlocking of the pores is triggered by the dissociation of the aptamer/thrombin complexes through the KP‐ or CE‐mediated elimination of the stabilizing K⁺ ions. In the third system, duplex DNA units lock the pores of MP‐SiO₂ NPs, and the release of the entrapped substrate is stimulated by the K⁺‐ion‐induced dissociation of the duplex caps through the formation of the K⁺‐stabilized G‐quadruplexes. The latter system is further implemented to release the anti‐cancer drug, doxorubicin, in the presence of K⁺ ions, from the MP‐SiO₂ NPs. Preliminary intracellular experiments reveal that doxorubicin‐loaded MP‐SiO₂ NPs lead to effective death of breast cancer cells.     

Suppressing Manganese Dissolution in Potassium Manganate with Rich Oxygen Defects Engaged High‐Energy‐Density and Durable Aqueous Zinc‐Ion Battery

The manganese dissolution leading to sharp capacity decline as well as the sluggish reaction kinetic are still major issues for manganese‐based materials as aqueous zinc‐ion batteries (ZIBs) cathodes. Here, a potassium‐ion‐stabilized and oxygen‐defect K_0.8Mn₈O₁₆ is reported as a high‐energy‐density and durable cathode for neutral aqueous ZIBs. A new insight into suppressing manganese dissolution via incorporation of K⁺ ions to intrinsically stabilize the Mn‐based cathodes is provided. A comprehensive study suggests that oxygen defects improve electrical conductivity and open the MnO₆ polyhedron walls for ion diffusion, which plays a critical role in the fast reaction kinetics and capacity improvement of K_0.8Mn₈O₁₆. In addition, direct evidence for the mechanistic details of simultaneous insertion and conversion reaction based on H⁺‐storage mechanism is demonstrated. As expected, a significant energy output of 398 W h kg^?1 (based on the mass of cathode) and an impressive durability over 1000 cycles with no obvious capacity fading are obtained. Such a high‐energy Zn‐K_0.8Mn₈O₁₆ battery, as well as the basic understanding of manganese dissolution and oxygen defects may open new opportunities toward high‐performance aqueous ZIBs.     

Development of Film Sensors Based on Conjugated Polymers for Copper (II) Ion Detection

A fluorescent film sensor was prepared by chemical modification of a polyfluorene derivative on a glass‐plate surface. X‐ray photoelectron spectroscopy and ellipsometry measurements demonstrate the covalent attachment of the polyfluorene derivative to the glass‐plate surface. The sensor was used to detect Cu²⁺ ions in aqueous solution by a mechanism exploiting fluorescence quenching of conjugated polymers. Among the tested metal ions, the film sensor presents good selectivity towards Cu²⁺ ions. Further experiments show that the sensing process is reversible. Moreover, sensory microarrays based on conjugated polymers targeting Cu²⁺ ions are constructed, which display similar sensing performance to that of the film sensor. The structural motif in which conjugated polymers are covalently confined to a solid substrate surface offers several attractive advantages for sensing applications. First, in comparison with film sensors in which small fluorescent molecules are employed as sensing elements, the sensitivity of our new film sensor is enhanced due to the signal‐amplifying effect of the conjugated polymers. Second, the film sensors or microarrays can be used in aqueous environments, which is crucial for their potential use in a wide range of real‐world systems. Since the sensing process is reversible, the sensing materials can be reused. Third, unlike physically coated polymer chains, the covalent attachment of the grafted chains onto a material surface precludes desorption and imparts long‐term stability of the polymer chains.     

Fast Potassium Storage in Hierarchical Ca0.5Ti2(PO4)3@C Microspheres Enabling High‐Performance Potassium‐Ion Capacitors

Hybrid potassium‐ion capacitors (KICs) show great promise for large‐scale storage on the power grid because of cost advantages, the weaker Lewis acidity of K⁺ and low redox potential of K⁺/K. However, a huge challenge remains for designing high‐performance K⁺ storage materials since K⁺ ions are heavier and larger than Li⁺ and Na⁺. Herein, the synthesis of hierarchical Ca_0.5Ti₂(PO₄)₃@C microspheres by use of the electrospraying method is reported. Benefiting from the rich vacancies in the crystal structure and rational nanostructural design, the hybrid Ca_0.5Ti₂(PO₄)₃@C electrode delivers a high reversible capacity (239 mA h g^?1) and superior rate performance (63 mA h g^?1 at 5 A g^?1). Moreover, the KIC employing a Ca_0.5Ti₂(PO₄)₃@C anode and activated carbon cathode, affords a high energy/power density (80 W h kg^?1 and 5144 W kg^?1) in a potential window of 1.0–4.0 V, as well as a long lifespan of over 4000 cycles. In addition, in situ X‐ray diffraction is used to unravel the structural transition in Ca_0.5Ti₂(PO₄)₃, suggesting a two‐phase transition above 0.5 V during the initial discharge and solid solution processes during the subsequent K⁺ insertion/extraction. The present study demonstrates a low‐cost potassium‐based energy storage device with high energy/power densities and a long lifespan.     

Flexible Electronics and Materials for Synchronized Stimulation and Monitoring in Multi‐Encephalic Regions

Simultaneous neuron stimulation and biophysiological sensing in multi‐encephalic regions can lead to profound understanding of neural pathways, neurotransmitter transportation, and nutrient metabolism. Here, a flexible electronic device with tentacle‐like channels radiating from a central wireless circuit is presented. The device is constructed by different organic and inorganic materials that have been made into thin‐film or nanoparticle formats. All channels have been equipped with flexible components for distributed and synchronized opto‐electrical stimulation, biopotential sensing, and ion concentration monitoring. They can be implanted into different brain regions through adaptive bending and individually addressed to follow programmable working sequences. Experimental results conducted in vitro and in vivo have demonstrated the capability in generating optical or electrical stimulation, while sensing 16‐channels biopotential and concentration of Ca²⁺, Na⁺, and K⁺ ions in distributed regions. Behavior and immunohistochemistry studies suggest potential applications in regulating brain functions for freely moving animals. In combination with various functional materials, the device can serve as a comprehensive research platform that can be modularized to accommodate different needs for brain studies, offering numerous possibilities and combinations to yield sophisticated neuromodulation and behavior regulation.     

Nanoparticle‐Based Fluoroionophore for Analysis of Potassium Ion Dynamics in 3D Tissue Models and In Vivo

The imaging of real‐time fluxes of K⁺ ions in live cell with high dynamic range (5–150 × 10^?3m ) is of paramount importance for neuroscience and physiology of the gastrointestinal tract, kidney, and other tissues. In particular, the research on high‐performance deep‐red fluorescent nanoparticle‐based biosensors is highly anticipated. It is found that boron‐dipyrromethene (BODIPY)‐based K⁺‐sensitive fluoroionophore FI3 encapsulated in cationic polymer RL100 nanoparticles displays unusually strong efficiency in staining of broad spectrum of cell models, such as primary neurons and intestinal organoids. Using comparison of brightness, photostability, and fluorescence lifetime imaging microscopy, it is confirmed that FI3 nanoparticles display distinctively superior intracellular staining compared to the free dye. FI3 nanoparticles in real‐time live cell imaging are evaluated and it is found highly useful for monitoring intra‐ and extracellular K⁺ dynamics in cultured neurons. Proof‐of‐concept in vivo brain imaging confirms applicability of the biosensor for visualization of epileptic seizures. Collectively, these data make fluoroionophore FI3 a versatile cross‐platform fluorescent biosensor, broadly compatible with diverse experimental models, and crown‐ether‐based polymer nanoparticles can provide a new venue for the design of efficient fluorescent probes.     

Cyclodextrin‐Threaded Conjugated Polyrotaxanes for Organic Electronics: The Influence of the Counter Cations

A systematic investigation is reported into the influence of the counter cations on the optical, electrical and electroluminescent properties of polyelectrolytic conjugated polymers and of their cyclodextrin‐threaded rotaxanes. We compare conjugated polyelectrolytes with sulfonated side groups where the anionic charge is balanced by Li⁺, K⁺, Cs⁺, tetramethylammonium (Me₄N⁺) and cryptate‐encapsulated potassium (K⁺@[2.2.2]). Narrowing (for the unthreaded analogues) and a slight red‐shift of the absorption spectra (for the rotaxanes) are found upon exchange of Li⁺ for larger cations, together with a blue‐shift and an efficiency enhancement of the luminescence. These effects are similar in nature to those induced by rotaxination, and are therefore assigned to a marked reduction of intermolecular interactions between the conjugated cores. Exchange of Li⁺ for K⁺, Cs⁺, or Me₄N⁺ results in a higher electroluminescence external quantum efficiency (EQE) for both polyrotaxanes and unthreaded polymers. For polyrotaxane‐based devices the EQE increased approximately 7 times upon substitution of Li⁺ with Cs⁺ or Me₄N⁺, thereby demonstrating the importance of the selection of the counter‐cations for optimizing the performance of polyelectrolytic conjugated polymers in light‐emitting devices.     

A Protein‐Nanocellulose Paper for Sensing Copper Ions at the Nano‐ to Micromolar Level

Tracing heavy metals is a crucial issue in both environmental and medical samples. In this work, a sensing biomolecule, the cyanobacterial C‐phycocyanin (CPC), is integrated into a nanocellulose matrix, and with this, a biosensor for copper ions is developed. The assembly of CPC‐functionalized nanocellulose into a red‐fluorescent, copper‐sensitive hybrid film “CySense”, enhances protein stability and facilitates the reuse and the regeneration of the sensor for several cycles over 7 days. CySense is suitable for the analysis of complex medical samples such as human serum filtrate. The reported biosensor reliably detects copper ion contents with a lower detection limit of 200 × 10^?9m and an IC50 of 4.9 × 10^?6m as changes in fluorescence emission intensity that can be measured with a fluorimeter or a microarray laser scanner.     

Fast Rate and Long Life Potassium‐Ion Based Dual‐Ion Battery through 3D Porous Organic Negative Electrode

Potassium‐based dual ion batteries (K‐DIBs) with potassium cation (K⁺) intercalation graphitic anodes have been investigated for their potential in large‐scale energy storage applications owing to their merits of low cost and environmental friendly. Nonetheless, graphite anodes are plagued by volume expansion from the large K⁺ ions and the co‐intercalation of solvent molecules during the charging. Accordingly, organic materials stand out for the flexible adjustable structures and abundant active sites, which can accommodate cations by multiple functional groups without structural collapse. However, K‐DIBs based on organic anodes have rarely been investigated. Herein, 3D porous dipotassium terephthalate nanosheets are synthesized via a freeze‐dry method as the K‐DIB anode, which can reversibly store K⁺ ions at a fast rate with a high specific capacity and robust stability due to the sufficient redox active sites and diffusion pathways of K⁺ ions in the 3D porous structure. Consequently, a novel K‐DIB configuration combining this fast kinetics organic anode and environmental friendly expanded graphite (EG) cathode is constructed (pK2TP//EG), which exhibits a high specific capacity (68 mAh g^‐1 at 2 C), good rate performance up to 20 C, and long cycling life with a capacity retention ~100% after 2000 cycles, which is the best performance observed among reported K‐DIBs.     

Hierarchical Ordered Dual‐Mesoporous Polypyrrole/Graphene Nanosheets as Bi‐Functional Active Materials for High‐Performance Planar Integrated System of Micro‐Supercapacitor and Gas Sensor

Planar integrated systems of micro‐supercapacitors (MSCs) and sensors are of profound importance for 3C electronics, but usually appear poor in compatibility due to the complex connections of device units with multiple mono‐functional materials. Herein, 2D hierarchical ordered dual‐mesoporous polypyrrole/graphene (DM‐PG) nanosheets are developed as bi‐functional active materials for a novel prototype planar integrated system of MSC and NH₃ sensor. Owing to effective coupling of conductive graphene and high‐sensitive pseudocapacitive polypyrrole, well‐defined dual‐mesopores of ≈7 and ≈18 nm, hierarchical mesoporous network, and large surface area of 112 m² g^?1, the resultant DM‐PG nanosheets exhibit extraordinary sensing response to NH₃ as low as 200 ppb, exceptional selectivity toward NH₃ that is much higher than other volatile organic compounds, and outstanding capacitance of 376 F g^?1 at 1 mV s^?1 for supercapacitors, simultaneously surpassing single‐mesoporous and non‐mesoporous counterparts. Importantly, the bi‐functional DM‐PG‐based MSC‐sensor integrated system represents rapid and stable response exposed to 10–40 ppm of NH₃ after only charging for 100 s, remarkable sensitivity of NH₃ detection that is close to DM‐PG‐based MSC‐free sensor, impressive flexibility with ≈82% of initial response value even at 180°, and enhanced overall compatibility, thereby holding great promise for ultrathin, miniaturized, body‐attachable, and portable detection of NH₃.     

A Substitution‐Dependent Light‐Up Fluorescence Probe for Selectively Detecting Fe3+ Ions and Its Cell Imaging Application

Deliberate design of specific and sensitive molecular probes with distinctive physical/chemical properties for analyte sensing is of great significance. Herein, by taking advantage of the position‐dependent substituent effects, an aggregation‐induced emission featured iron (III) probe from ortho‐substituted pyridinyl‐functionalized tetraphenylethylene (TPE‐o‐Py) is synthesized. It displays high sensitivity and selectivity toward iron (III) detection. The recognition arises from the position isomer of ortho‐substitution, and the fact that TPE‐o‐Py has a low acid dissociation constant (pK _a) that is close to that of hydrolyzed Fe³⁺. Importantly, TPE‐o‐Py as a light‐up fluorescence probe could be employed for Fe³⁺ sensing in living cells with a pronounced red‐shift in fluorescence emission.     

Face‐to‐Face Contact and Open‐Void Coinvolved Si/C Nanohybrids Lithium‐Ion Battery Anodes with Extremely Long Cycle Life

To develop high‐performance anode materials of lithium‐ion batteries (LIBs) instead of commercial graphite for practical applications, herein, a layer of silicon has been well‐anchored onto a 3D graphene/carbon nanotube (CNT) aerogels (CAs) framework with face‐to‐face contact and balanced open void by a simple chemical vapor deposition strategy. The engineered contact interface between CAs and Si creates high‐efficiency channels for the rapid electrons and lithium ions transport, and meanwhile, the balanced open‐void allows the free expansion of Si during cycling while maintaining high structural integrity due to the robust mechanical strength of 3D CAs framework. As a consequence, the as‐synthesized Si/CAs nanohybrids are highly stable anode materials for LIBs with a high reversible discharge capacity (1498 mAh g^?1 at 200 mA g^?1) and excellent rate capability (462 mAh g^?1 at 10 000 mA g^?1), which is much better than Si/graphene‐CNTs‐mixture (51 mAh g^?1 at 10 000 mA g^?1). More significantly, it is found that the Si/CAs nanohybrids display no obvious capacity decline even after 2000 cycles at a high current density of 10 000 mA g^?1. The present Si/CAs nanohybrids are one of the most stable Si‐based anode materials ever reported for LIBs to date.     

Gold‐Nanocluster‐Based Fluorescent Sensors for Highly Sensitive and Selective Detection of Cyanide in Water

A novel, gold‐nanocluster‐based fluorescent sensor for cyanide in aqueous solution, which is based on the cyanide etching‐induced fluorescence quenching of gold nanoclusters, is reported. In addition to offering high selectivity due to the unique Elsner reaction between cyanide and the gold atoms of gold nanoclusters, this facile, environmentally friendly and cost‐effective method provides high sensitivity. With this sensor, the lowest concentration to quantify cyanide ions could be down to 200 × 10^?9 M , which is approximately 14 times lower than the maximum level (2.7 × 10^?6 M ) of cyanide in drinking water permitted by the World Health Organization (WHO). Furthermore, several real water samples spiked with cyanide, including local groundwater, tap water, pond water, and lake water, are analyzed using the sensing system, and experimental results show that this fluorescent sensor exhibits excellent recoveries (over 93%). This gold‐nanocluster‐based fluorescent sensor could find applications in highly sensitive and selective detection of cyanide in food, soil, water, and biological samples.