Neuromorphic computing has been extensively studied to mimic the brain functions of perception, learning, and memory because it may overcome the von Neumann bottleneck. Here, with the light‐induced ...bidirectional photoresponse of the proposed Bi2O2Se/graphene hybrid structure, its potential use in next‐generation neuromorphic hardware is examined with three distinct optoelectronic applications. First, a photodetector based on a Bi2O2Se/graphene hybrid structure presents positive and negative photoresponsibility of 88 and −110 A W−1 achieved by the excitation of visible wavelength and ultraviolet wavelength light at intensities of 1.2 and 0.3 mW cm−2, respectively. Second, this unique photoresponse contributes to the realization of all optically stimulated long‐term potentiation or long‐term depression to mimic synaptic short‐term plasticity and long‐term plasticity, which are attributed to the combined effect of photoconductivity, bolometric, and photoinduced desorption. Third, the devices are applied to perform digital logic functions, such as “AND” and “OR,” using full light modulation. The proposed Bi2O2Se/graphene‐based optoelectronic device represents an innovative and efficient building block for the development of future multifunctional artificial neuromorphic systems.
All‐optical synapses based on a 2D Bi2O2Se/graphene hybrid structure can yield positive photoresponses under visible light and negative photoresponses under 365 nm illumination without the extra electrical control. Contributing to this unique optoelectronic property, the single two‐terminal device with fully optical operations is demonstrated for the photodetector, optoelectronic synapses, and optical logic functions.
Lithium metal is an ideal anode for lithium batteries due to its low electrochemical potential and high theoretical capacity. However, safety issues arising from lithium dendrite growth have ...significantly reduced the practical applicability of lithium metal batteries. Here, we report the addition of octaphenyl polyoxyethylene as an electrolyte additive to enable a stable complex layer on the surface of the lithium anode. This surface layer not only promotes uniform lithium deposition, but also facilitates the formation of a robust solid-electrolyte interface film comprising cross-linked polymer. As a result, lithium|lithium symmetric cells constructed using the octaphenyl polyoxyethylene additive exhibit excellent cycling stability over 400 cycles at 1 mA cm
, and outstanding rate performance up to 4 mA cm
. Full cells assembled with a LiFePO
cathode exhibit high rate capability and impressive cyclability, with capacity decay of only 0.023% per cycle.
Lithium metal is among the most promising anode materials for high-energy batteries due to its high theoretical capacity and lowest electrochemical potential. However, dendrite formation is a major ...challenge, which can result in fire and explosion of the batteries. Herein, we report on hexadecyl trimethylammonium chloride (CTAC) as an electrolyte additive that can suppress the growth of lithium dendrites by lithiophobic repulsion mechanisms. During the lithium plating process, cationic surfactant molecules can aggregate around protuberances via electrostatic attraction, forming a nonpolar lithiophobic protective outer layer, which drives the deposition of lithium ions to adjacent regions to produce dendrite-free uniform Li deposits. Thus, an excellent cycle of 300 h at 1.0 mA cm–2 and rate performance up to 4 mA cm–2 are available safely in symmetric Li|Li cells. In particular, significantly enhanced cycle and rate performance were achieved when the electrolyte with CTAC additives was used in lithium–sulfur and Li|LiNi0.5Co0.2Mn0.3O2 full cells. The effects of carbon chains, anions of surfactant, and electrostatic repulsion on the deposition of lithium anodes are reported. This work advances research in inhibiting Li dendrite growth with a new electrolyte additive based on cationic surfactants.
Long-term stability and high-rate capability have been the major challenges of sodium-ion batteries. Layered electroactive materials with mechanically robust, chemically stable, electrically and ...ironically conductive networks can effectively address these issues. Herein we have successfully directed carbon nanofibers to vertically penetrate through graphene sheets, constructing robust carbon nanofiber interpenetrated graphene architecture. Molybdenum disulfide nanoflakes are then grown in situ alongside the entire framework, yielding molybdenum disulfide@carbon nanofiber interpenetrated graphene structure. In such a design, carbon nanofibers prevent the restacking of graphene sheets and provide ample space between graphene sheets, enabling a strong structure that maintains exceptional mechanical integrity and excellent electrical conductivity. The as-prepared sodium ion battery delivers outstanding electrochemical performance and ultrahigh stability, achieving a remarkable specific capacity of 598 mAh g
, long-term cycling stability up to 1000 cycles, and an excellent rate performance even at a high current density up to 10 A g
.
The heptafluoroisopropyl group (CF(CF3)2) is prevalent in pharmaceuticals and agrichemicals. However, heptafluoroisopropoxylated (OCF(CF3)2) compounds remain largely underexplored, presumably due to ...the lack of efficient access to these compounds. Herein, we disclose the practical and efficient heptafluoroisopropoxylation reactions through the invention of a series of redox‐active N‐OCF(CF3)2 reagents. These reagents were readily prepared from the oxidative heptafluoroisopropylation of hydroxylamines with AgCF(CF3)2. The substitutions on the nitrogen atom significantly affected the properties and reactivities of N‐OCF(CF3)2 reagents. Accordingly, two types of N‐OCF(CF3)2 reagents including N‐OCF(CF3)2 phthalimide A and N‐OCF(CF3)2 benzotriazolium salt O′ were used as OCF(CF3)2 anion and radical precursors, respectively. This protocol enables the direct heptafluoroisopropoxylation of a range of substrates, delivering the corresponding products in moderate to excellent yields.
Redox‐active heptafluoroisopropoxylating reagents were conveniently prepared from the oxidative heptafluoroisopropylation of hydroxylamines, and then were successfully used for the synthesis of a series of alkyl(aryl) heptafluoroisopropyl ethers.
Fused Deposition Modeling (FDM) can be used to manufacture any complex geometry and internal structures, and it has been widely applied in many industries, such as the biomedical, manufacturing, ...aerospace, automobile, industrial, and building industries. The purpose of this research is to characterize the polylactic acid (PLA) and polyethylene terephthalate glycol (PETG) materials of FDM under four loading conditions (tension, compression, bending, and thermal deformation), in order to obtain data regarding different printing temperatures and speeds. The results indicated that PLA and PETG materials exhibit an obvious tensile and compression asymmetry. It was observed that the mechanical properties (tension, compression, and bending) of PLA and PETG are increased at higher printing temperatures, and that the effect of speed on PLA and PETG shows different results. In addition, the mechanical properties of PLA are greater than those of PETG, but the thermal deformation is the opposite. The above results will be a great help for researchers who are working with polymers and FDM technology to achieve sustainability.
Metallic lithium (Li) is a promising anode for next‐generation high‐energy‐density batteries, but its applications are still hampered due to the limited charging/discharging rate and poor cycling ...performance. Here, a hierarchical 3D porous architecture is designed with a binary network of continuous silver nanowires assembled on an interconnected 3D graphene skeleton as the host for Li‐metal composite anodes, which offers a significant boost in both charging/discharging rates and long‐term cycling performance for Li‐metal batteries. This unique hierarchical binary network structure in conjunction with optimized material combination provides ultrafast, continuous, and smooth electron transportation channel and non‐nucleation barrier sites to direct and confine Li deposition. It also offers outstanding mechanical strength and toughness to support massive Li deposition and buffer the internal stress fluctuations during long‐term repeated Li stripping/plating thereby minimizing fundamental issues of dendrite formation and volume change even under ultrafast charging/discharging rates. As a result, the composite anode using this hierarchical host can work smoothly at an unprecedented high current density of 40 mA cm‐2 over 1000 plating/stripping cycles with low overpotential (<120 mV) in symmetric cells. The as‐constructed full cell, paired with LiNi0.5Co0.2Mn0.3O2 cathode, also exhibits excellent rate capability and high‐rate cycling stability.
A hierarchical 3D porous architecture with a binary network of a continuous 2D silver‐nanowire nanonetwork assembling on an interconnected 3D graphene skeleton is constructed as the host for Li‐metal composite anodes, which enables a significant boost on both charging/discharging rate and long‐term cycling performance for Li‐metal batteries.
Epicatechin (EC), a flavonoid present in various foods including cocoa, dark chocolate, berries, and tea, has recently been reported to promote general health and survival of old mice fed a standard ...chow diet. This is considered a novel discovery in the field of identifying natural compounds to extend lifespan, given that presumably popular anti-aging natural agents including resveratrol, green tea extract, and curcumin had failed in extending the lifespan of standard chow-diet-fed mice. However, the anti-aging mechanism of EC is not fully understood, thus impeding the potential application of this natural compound in improving a healthy lifespan in humans. In this review, we first summarized the main dietary sources that contain a significant amount of EC and recent research regarding the absorption, metabolism and distribution of EC in humans and rodents. The review is then focused on the anti-aging effects of EC in cultured cells, animals and humans with the possible physiological, cellular and molecular mechanisms underlying its lifespan-extending effects.
The nervous system is a vital part of organisms to survive and it endows them with remarkable abilities, such as perception, recognition, regulation, learning, and decision‐making, by intertwining ...myriad neurons. To realize such outstanding efficacies and functions, many artificial devices and systems have been investigated to emulate the operating principles of the nervous system. Here, an artificial reflex arc (ARA) and artificial pain modulation system (APMS) are proposed to imitate the unconscious behaviors of the spinal cord. GdxOy‐ and AlxOy‐based charge‐regulated field‐effect transistors (CRFETs) with a monolayer graphene channel are fabricated and adopted as inhibitory and excitatory synapses, respectively, under the same pulse signals to mimic the biological reflex arc through a connection with a poly(vinylidene fluoride‐co‐trifluoroethylene)‐based actuator. Additionally, a memristor is integrated with a CRFET as the interneuron to regulate the Dirac point by controlling the voltage drop on the graphene channel, analogous to the descending pain‐inhibition system in the spinal cord, to prevent excessive pain perception. The proposed ARA and APMS provide a significant step forward to realizing the functions of the nervous system, giving promising potential for developing future intelligent alarm systems, neuroprosthetics, and neurorobotics.
Charge‐regulated field‐effect transistors (CRFETs) with polarity‐differentiated dielectric materials and a monolayer graphene channel are developed to mimic a reflex arc and pain modulation system of the spinal cord. By integrating actuators and memristors with CRFETs, reflex actions and pain sensation under noxious stimuli are realized, offering a new method to emulate the functionalities of the nervous system.
Being simple, inexpensive, scalable and environmentally friendly, microporous biomass biochars have been attracting enthusiastic attention for application in lithium-sulfur （Li-S） batteries. Herein, ...porous bamboo biochar is activated via a KOH/annealing process that creates a microporous structure, boosts surface area and enhances electronic conductivity. The treated sample is used to encapsulate sulfur to prepare a microporous bamboo carbon-sulfur （BC-S） nanocomposite for use as the cathode for Li-S batteries for the first time. The BC-S nanocomposite with 50 wt.% sulfur content delivers a high initial capacity of 1,295 mA-h/g at a low discharge rate of 160 mA/g and high capacity retention of 550 mA-h/g after 150 cycles at a high discharge rate of 800 mA/g with excellent coulombic efficiency （995%）. This suggests that the BC-S nanocomposite could be a promising cathode material for Li-S batteries.
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