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The emulation of human multisensory functions to construct artificial perception systems is an intriguing challenge for developing humanoid robotics and cross‐modal human–machine interfaces. Inspired by human multisensory signal generation and neuroplasticity‐based signal processing, here, an artificial perceptual neuro array with visual‐tactile sensing, processing, learning, and memory is demonstrated. The neuromorphic bimodal perception array compactly combines an artificial photoelectric synapse network and an integrated mechanoluminescent layer, endowing individual and synergistic plastic modulation of optical and mechanical information, including short‐term memory, long‐term memory, paired pulse facilitation, and "learning‐experience" behavior. Sequential or superimposed visual and tactile stimuli inputs can efficiently simulate the associative learning process of "Pavlov's dog". The fusion of visual and tactile modulation enables enhanced memory of the stimulation image during the learning process. A machine‐learning algorithm is coupled with an artificial neural network for pattern recognition, achieving a recognition accuracy of 70% for bimodal training, which is higher than that obtained by unimodal training. In addition, the artificial perceptual neuron has a low energy consumption of ∼20 pJ. With its mechanical compliance and simple architecture, the neuromorphic bimodal perception array has promising applications in large‐scale cross‐modal interactions and high‐throughput intelligent perceptions. [ABSTRACT FROM AUTHOR]

User‐interactive interfaces, converting tactile stimuli into readable signals to users and devices simultaneously, improve the communication and interaction between human and machines and therefore greatly contribute to the safety and dexterity during the interactions. However, the concomitant challenges of current user‐interactive interfaces such as complex architecture, massive electrodes and fussy cable connections, bulky and unhandy power supply, and deficiency in multistimuli responses have yet to be solved. Herein, an all‐optical tactile sensing platform consisting of heterogeneous mechanoluminescent materials and polymer matrix is proposed for the conversion of multiple tactile stimuli into heterochromatic lights in an untethered and self‐powered manner. The all‐optical tactile sensing platform can respond to tiny shear force such as fingertip slipping with a low limit of 2 N and wide range of strains ranging from 30% to 70% with appropriate discrimination. Most importantly, the visualization of tactile stimuli with human‐ and machine‐readability and vividness permit remote and wireless user‐interactive applications such as videogames and RC car control, assisted with the developed method of active optical signal recognition. This work presents a paradigm shift to user‐interactive interfaces, boosting their implementation in multitudinous areas such as artificial intelligences and the Internet of Things. [ABSTRACT FROM AUTHOR]

Developing high‐efficiency, cost‐effective, and durable electrodes is significant for electrochemical capacitors and electrocatalysis. Herein, a 3D bifunctional electrode consisting of nickel hydroxide nanosheets@nickel sulfide nanocubes arrays on Ni foam (Ni(OH)2@Ni3S2/NF) obtained from a Prussian blue analogue‐based precursor is reported. The 3D higher‐order porous structure and synergistic effect of different compositions endow the electrode with large specific surface area, facile ion/electron transport path, and improved conductivity. As a result, the Ni(OH)2@Ni3S2/NF electrode exhibits a high specific capacity of 211 mA h g−1 at a current density of 1 A g−1 and 73 % capacity retention after 5000 cycles at 5 A g−1. Moreover, the Ni(OH)2@Ni3S2/NF electrode has superior electrocatalytic activity for the hydrogen evolution reaction with low overpotentials of 140 and 210 mV at current densities of 10 and 100 mA cm−2, respectively. The synthetic strategy for the unique higher‐order porous structure can be extended to fabricate other composite materials for energy storage and conversion. [ABSTRACT FROM AUTHOR]

Highly uniform dispersed bimetallic Pt3Zn alloy nanocrystals (NCs) with unique geometries are obtained via a facile one‐pot synthesis process by regulating different reductants. To investigate the morphology and composition of the prepared catalysts, the transmission electron microscopy, X‐ray diffraction and X‐ray photoelectron spectroscopy are utilized. Electrochemical measurements reveal that the Pt3Zn NCs significantly exhibited larger electrochemically active surface areas and excellent catalytic activity towards electro‐oxidation of methanol and ethanol in comparison to the commercial Pt/C. The optimized Pt3Zn (AA) NCs exhibit excellent mass activities in both methanol oxidation reaction (1251.4 mA mgPt−1) and ethanol oxidation reaction (975.7 mA mgPt−1) in acidic media, which are respectively 4.28 times and 3.02 times higher than those of commercial Pt/C. Moreover, the Pt3Zn NCs show a higher stability and better resistance to the COads poisoning. The activity enhancements are attributed to electronic effects and a bifunctional mechanism. [ABSTRACT FROM AUTHOR]

The design of electrode materials with rational core/shell structures is promising for improving the electrochemical properties of supercapacitors. Hence, hierarchical FeCo2S4@FeNi2S4 core/shell nanostructures on Ni foam were fabricated by a simple hydrothermal method. Owing to their structure and synergistic effect, they deliver an excellent specific capacitance of 2393 F g−1 at 1 A g−1 and long cycle lifespan as positive electrode materials. An asymmetric supercapacitor device with FeCo2S4@FeNi2S4 as positive electrode and graphene as negative electrode exhibited a specific capacitance of 133.2 F g−1 at 1 A g−1 and a high energy density of 47.37 W h kg−1 at a power density of 800 W kg−1. Moreover, the device showed remarkable cycling stability with 87.0 % specific‐capacitance retention after 5000 cycles at 2 A g−1. These results demonstrate that the hierarchical FeCo2S4@FeNi2S4 core/shell structures have great potential in the field of electrochemical energy storage. [ABSTRACT FROM AUTHOR]

The oxygen anion or, equivalently, the oxygen vacancy transport process is a key issue in valence change memory. Herein, based on the Aurivillius phase oxygen ion conductor Bi2MoO6, resistive random access memory devices with a Pt/Bi2MoO6/fluorine-doped SnO2 structure show bipolar resistive switching behavior with high stability, excellent data retention, and potential for multilevel data storage. In addition, dielectric spectroscopy is employed to probe the characteristics of both high resistance and low resistance states to confirm oxygen ion migration and understand the dynamics of oxygen vacancies. A very large change of nearly three orders of magnitude in loss tangent is found. It has been confirmed that one relaxation peak in the LRS originates from the oriented polarization of oxygen vacancies. The activation energy for oxygen vacancy migration of 0.21 eV and the relaxation time of 6.9 × 10−8 s are further deduced. In combination with first-principles calculations, a mechanism involving the formation and rupture of conductive filaments formed by oxygen vacancies is proposed to explain the resistive switching behavior. This work provides meaningful insights for identifying the exact mobile species in resistive switching and understanding its dynamic relaxation mechanism. [ABSTRACT FROM AUTHOR]

In order to address the issue of large volume expansion and poor electrical conductivity of Fe3O4‐based anodes for lithium‐ion batteries, carbon and SiOx/SiC heterojunction double‐shell coated Fe3O4(FexSiy) nanocomposites were synthesized by crosslinking, pyrolysis and decarbonization of sol particles. The particles were produced by the reaction of iron carbonyl with liquid polycarbosilane using pitch as isolator, which is a low cost and easy to scale up preparation method. It is found that the double‐shell structure of the nanoparticles not only solves the problem of comminution of Fe3O4 during cycling, but also ensures stable cycling and superior rate performance. The FeOSiC‐30 anode delivers a high reversible capacity (1357.2 mAh g−1 for 550 cycles at 1 A g−1 and 1060.7 mAh g−1 for 2500 cycles at 5 A g−1). The excellent electrochemical performance can be contributed to the novel structure: 1) the uniform carbon layer can improve the electrical conductivity and ensure the formation of a stable SEI; 2) different active materials can relieve the stress caused by volume variation and also contribute additional capacity; 3) the small particle size can offer a strong kinetic of electrochemical reactions and lithium ion transfer. These results can strongly support the improvement of the capacity of Fe3O4‐based anodes by the unique multi‐function structural design, also providing new pathways for the design of other electrode materials. [ABSTRACT FROM AUTHOR]

Lead halide perovskites‐based memory devices have attracted considerable interest due to their unique current–voltage (I–V) hysteresis. Herein, all‐inorganic CsPbI3 perovskite film surviving 30 d of air storage is prepared by using a poly‐vinylpyrrolidone‐assisted passivation method under fully open‐air condition. Afterwards, a memory device with a sandwich structure of Ag/CsPbI3/indium tin oxide is manufactured. From I–V characteristics of pristine device, a spontaneous reaction between the active Ag electrode and I− ions under air exposure is suggested. Furthermore, complete degradation of Ag electrode and formation of AgIx are verified, which also accompanies with generation of more iodine vacancies (VI) in perovskite film. The memory device with AgIx layer shows a bipolar resistive switching behavior, ultrahigh ON/OFF ratio (above 106), nonvolatile, reliable, and reproducible switching performance. Cell area and temperature dependent characteristics propose that the resistive switching is dominated by VI filament in low‐resistance state and thermally assisted hopping in high‐resistance state. This study provides a new insight to understand switching behavior from the way of electrode degradation and metal iodide formation in lead iodide perovskites‐based memory devices and also suggests a potential application for AgIx‐induced resistive switching in CsPbI3‐based memory device. All‐inorganic CsPbI3 perovskite film is prepared by using a poly‐vinylpyrrolidone‐assisted passivation method. Complete degradation of Ag electrode and formation of AgIx in memory device of Ag/CsPbI3/indium tin oxide are verified which also accompanies with generation of more iodine vacancies. The memory device with AgIx layer shows a bipolar resistive switching behavior, ultrahigh ON/OFF ratio, nonvolatile, reliable, and reproducible switching performance. [ABSTRACT FROM AUTHOR]

Halide perovskites featuring remarkable optoelectronic properties hold great potential for threshold switching devices (TSDs) that are of primary importance to next-generation memristors and neuromorphic computers. However, such devices are still in their infancy due to the unsolved challenges of high threshold voltage, poor stability, and lead-containing features. Herein, a unipolar TSD based on an all-inorganic halide perovskite of CsCu 2 I 3 is demonstrated, exhibiting the fascinating attributes of a low threshold voltage of 0.54 V, a high ON/OFF ratio of 10 4 , robust air stability over 70 days, a steep switching slope of 6.2 mV·decade -1 , and lead-free composition. Moreover, the threshold voltage can be further reduced to 0.23 V using UV illumination to reduce the barrier of iodide ion migration. The multilevel threshold switching behavior can be realized through the modulation of either the compliance current or the scan rate. The TSD with mechanical compliance and transparency is also demonstrated. This work enriches TSDs with expanded perovskite materials, boosting the related applications of this emerging class of device families.

Developing high-efficiency, cost-effective, and durable electrodes is significant for electrochemical capacitors and electrocatalysis. Herein, a 3D bifunctional electrode consisting of nickel hydroxide nanosheets@nickel sulfide nanocubes arrays on Ni foam (Ni(OH) 2 @Ni 3 S 2 /NF) obtained from a Prussian blue analogue-based precursor is reported. The 3D higher-order porous structure and synergistic effect of different compositions endow the electrode with large specific surface area, facile ion/electron transport path, and improved conductivity. As a result, the Ni(OH) 2 @Ni 3 S 2 /NF electrode exhibits a high specific capacity of 211 mA h g -1 at a current density of 1 A g -1 and 73 % capacity retention after 5000 cycles at 5 A g -1 . Moreover, the Ni(OH) 2 @Ni 3 S 2 /NF electrode has superior electrocatalytic activity for the hydrogen evolution reaction with low overpotentials of 140 and 210 mV at current densities of 10 and 100 mA cm -2 , respectively. The synthetic strategy for the unique higher-order porous structure can be extended to fabricate other composite materials for energy storage and conversion., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The design of electrode materials with rational core/shell structures is promising for improving the electrochemical properties of supercapacitors. Hence, hierarchical FeCo 2 S 4 @FeNi 2 S 4 core/shell nanostructures on Ni foam were fabricated by a simple hydrothermal method. Owing to their structure and synergistic effect, they deliver an excellent specific capacitance of 2393 F g -1 at 1 A g -1 and long cycle lifespan as positive electrode materials. An asymmetric supercapacitor device with FeCo 2 S 4 @FeNi 2 S 4 as positive electrode and graphene as negative electrode exhibited a specific capacitance of 133.2 F g -1 at 1 A g -1 and a high energy density of 47.37 W h kg -1 at a power density of 800 W kg -1 . Moreover, the device showed remarkable cycling stability with 87.0 % specific-capacitance retention after 5000 cycles at 2 A g -1 . These results demonstrate that the hierarchical FeCo 2 S 4 @FeNi 2 S 4 core/shell structures have great potential in the field of electrochemical energy storage., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

All-inorganic CsPb 1- x Bi x I 3 perovskite film was successfully fabricated by incorporating Bi 3+ in CsPbI 3 to stabilize the cubic lattice. Furthermore, the perovskite film was applied to manufacture a simple Ag/CsPb 1- x Bi x I 3 /indium tin oxide (ITO) memory device with a bipolar resistive switching behavior. Nonvolatile, reliable, and reproducible switching properties are demonstrated through retention and endurance test under fully open-air conditions. The memory device also presents highly uniform and long-term stable characteristics. Importantly, by modulating the reset stop voltages, multilevel high-resistance states are observed for the first time in lead halide perovskite memory device. The resistive switching behavior is proposed to explain the formation and partial rupture of conductive multifilament that are dominated by the migration of iodine ions and their corresponding vacancies in perovskite film. This study suggests Ag/CsPb 1- x Bi x I 3 /ITO device potential application for multilevel data storage in a nonvolatile memory device.