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This article provides a review of various types of self-rechargeable batteries powered by ubiquitous clean and sustainable energy sources.

The N-type negative difference resistance (NDR) is characterized by the peak/valley voltage (Vp/Vv) and the corresponding current (Ip/Iv). The N-type NDR is observed in the resistive switching (RS) memory device of Ag|TiO2|F-doped SnO2 at room temperature. After the TiO2 film is equipped with a nanoporous array, the ∼1.2 V gap voltage between Vp and Vv is effectively downscaled to ∼0.5 V, and the gap current of ∼7.23 mA between Ip and Iv is improved to ∼30 mA. It demonstrates that a lower power consumption and faster switching time of the NDR can be obtained in the memristor. Compensations and synergies among the nanoscale conduction filaments (OH-, Ag+, and Vo) are responsible for the refining NDR behavior in our devices. This work provides an efficient method to construct a high-performance N-type NDR effect at room temperature and gives a new horizon on the coexistence of this type of NDR effect and RS memory behaviors.

The memristor-based neuromorphic computing application, which is highly flexible and capable of handling large amounts of parallel information, is one of the major breakthroughs in the past decade....

Using the earth-abundant natural biomaterials to manufacture functional electronic devices meets the sustainable requirement of green electronics, especially for the practical application of memristors in data storage and neuromorphic computing. However, the sneak currents flowing though the unselected cells in a large-scale cross-bar memristor array is one of the major problems which need to be tackled. The self-selecting memristors can solve the problem to develop compact and concise integrated circuits. Here, a sustainable natural biomaterial (anthocyanin, C

The information technologies have been increasing exponentially following Moore's law over the past decades. This has fundamentally changed the ways of work and life. However, further improving data process efficiency is facing great challenges because of physical and architectural limitations. More powerful computational methodologies are crucial to fulfill the technology gap in the post-Moore's law period. The memristor exhibits promising prospects in information storage, high-performance computing, and artificial intelligence. Since the memristor was theoretically predicted by L. O. Chua in 1971 and experimentally confirmed by HP Laboratories in 2008, it has attracted great attention from worldwide researchers. The intrinsic properties of memristors, such as simple structure, low power consumption, compatibility with the complementary metal oxide-semiconductor (CMOS) process, and dual functionalities of the data storage and computation, demonstrate great prospects in many applications. In this review, we cover the memristor-relevant computing technologies, from basic materials to in-memory computing and future prospects. First, the materials and mechanisms in the memristor are discussed. Then, we present the development of the memristor in the domains of the synapse simulating, in-memory logic computing, deep neural networks (DNNs) and spiking neural networks (SNNs). Finally, the existent technology challenges and outlook of the state-of-art applications are proposed.

Alcohol has a potential health risk to human health, so it is important to realise the rapid detection of alcohols. Based on this, the nano Na2Mg(CO3)2 was prepared by a simple hydrothermal method to establish a cataluminescence (CTL) gas sensor for alcohols. The Na2Mg(CO3)2with highly purified quality was characterised by scanning electron microscope, energy dispersive spectroscopy and the powder X-ray diffraction. The results show that the nano Na2Mg(CO3)2 is a peony-like substance with a large surface area, which will be beneficial to produce ultra-weak chemiluminescence reaction between the detector and the material. The peony-like Na2Mg(CO3)2 has good CTL response to alcohols (methanol, ethanol, n-propanol and n-butanol), showing high selectivity. The response time of Na2Mg(CO3)2 for four alcohols is between 1 and 2 s, which indicate that the material has the advantage of rapid response. The limit of detection of four alcohols defined as 3 N/S is about 7.91, 4.75, 6.69 and 8.10 mg/l, respectively. The optimum reaction conditions of the gas sensor based on nano Na2Mg(CO3)2 are mild and this nanomaterial can be used for alcohol detection.

It is well known that the reprogrammable device is one of the important needs for circuit design. In this paper, nanolayered TiO2 and maple leaves (ML) are combined to form a functional layer (TiO2...

Complex three-dimensional nanosheet structure of ZnxFeyO was prepared by highly stable co-sputtering oblique angle deposition. Scanning electron microscopy was employed to observe surface morphology evolution of ZnxFeyO with different Fe concentrations. X-ray diffraction was employed to analyze compositions of ZnO, ZnFe2O4, and ZnFe2O4/Fe2O3 with Fe doping. Furthermore, specific nanostructures of ZnxFeyO decreased band gap and increased visible-light absorption ability. The ZnFe2O4/Fe2O3 sample exhibited higher photocatalytic efficiency than those of other films for the degradation of methylene blue. Addition of Fe led to the enhancement of photoelectrochemical properties of ZnFe2O4/Fe2O3 compared to pure ZnO and Fe2O3, and photocurrent response of ZnFe2O4/Fe2O3 was ~10 times than that of pure ZnO at constant potential of −0.2 V (vs. Ag/AgCl).

The memristive effect become a bio-electronics research focus with the development of sustainable systems and the application of multifunctional electronic devices. In this paper, the natural Lophatherum gracile Brongn (LGB) was employed as active layer to prepare Ag/LGB/fluorine-doped tin oxide (FTO) bio-memristor. Further, different doping ratios nano silver powders (Ag nanoparticle) were doped into LGB functional layers at 0 wt%, 0.2 wt%, 0.33 wt%, 1.0 wt%, 2.0 wt%, 10.0 wt% and 20.0 wt%. It is found that the capacitive-coupled memristive performance of the Ag/Ag-doped-LGB/FTO devices was markedly changed. Finally, it is confirmed that Ag ions transferring and Ag filament formation under the applied voltage are responsible for capacitive-coupled memristive behavior. This research has revealed the realization of capacitive-coupled memristive effect of bio-memristor, which opens a new way to achieve multifunctional performance for electronic device.

Fe3O4 nanospheres (Fe3O4-S) synthesized via a facile one-pot solvothermal method were used for H2O2 activation and tetracycline (TC) elimination from aqueous solutions. It can be found that more than 80% of TC was degraded in the Fe3O4-S/H2O2 system. Besides, batch experiments were conducted to investigate the effects of different parameters such as catalyst dosages, H2O2 concentration, pH values and temperature on the degradation of TC, and these experimental results were also described by the pseudo-first-order model. Radical quenching experiments and an electron paramagnetic resonance (EPR) technique revealed that ˙OH and ˙O2−/˙HO2 were involved and ˙OH generated on the surface of Fe3O4-S played a main role in TC degradation. The XPS observations demonstrated that the surface FeII participated in the H2O2 activation through the redox reactions. Moreover, thirteen intermediate products were monitored by the LC–MS and possible degradation pathways of TC were accordingly proposed. The Fe3O4-S catalyst exhibited good reusability and the catalytic performance of it did not show any significant decrease even after five trials. It was worth noting that the optimal pH for TC degradation was expanded to neutral pH conditions by using the Fe3O4-S/H2O2 system. Additionally, Fe3O4-S was easily separated from the reaction solutions by virtue of its magnetism (66.8 emu g−1), which is beneficial for reuse of the catalysts.

The resistive random access memory (RRAM) based on resistive switching effect has considered to be the most advanced next generation memory, in which the switching direction determines the order of reading-writing. In this work, the rare-earth metal Er2O3 was used as functional layer, and Ag and indium-tin-oxide (ITO) are selected as top and bottom electrode to fabricate resistive switching device. Further, it is observed that the switching direction and memory window of resistive switching device can be regulated by exchanging top and bottom electrode. Moreover, the complementary switching memory behavior in Ag/Er2O3/ITO/Er2O3/Ag structure was also observed. Through mechanism analysis, it is expected that the barrier changes and metal-ions oxidation-reduction should be responsible for the conversion of switching direction and regulation of memory window. This work opens up a way to the development of next generation new concept memory.

A novel technology (co-sputtering oblique angle deposition) was used for fabricating W-doped Bi 2 O 3 films. After further annealing at 500 °C, the surface morphologies and microstructures of the films were characterized by scanning electron microscopy and X-ray diffraction. With increase in the sputtering current of W target in co-sputtering process, the surface morphology of W-doped Bi 2 O 3 films changed significantly. The mechanism of morphology evolution was systematically studied. The optical properties of W-doped Bi 2 O 3 films such as band gap and photocatalytic performance were also investigated. The results indicate that this co-sputtering oblique angle deposition technology is a promising new method for investigating the nanostructures photocatalytic and other performance of doped materials.

With the increasing demand for green electronic devices, the electronic devices based on biomaterials have been developed vigorously. Especially, the biomemristive memory device, which is prepared using biomaterials as functional layers, has shown great potential and application value in green and sustainable bioelectronic devices. In this work, the collagen, for the first time, was extracted from pigskin and utilized as the intermediate insulating layer for constructing two biomemoristive memory devices with Ag/Bio-film/ITO and Ag/Bio-film/Ti structures, in which it can be found that the high-resistance state/low-resistance state resistance ratio is ∼10 when the ITO was used as bottom electrode but it can be increased to ∼100 by using Ti as bottom electrode. Through further data analysis, we propose a mechanism of ions' redox and defect state filling to explain the switching mechanism of these devices. Our work indicates that the natural biomaterials which were derived from animals can be used to prepare the degradable and biocompatible bioelectronics devices.

Since conventional graphite-based anode possesses a low capacity, seeking for high-capacity anode candidates becomes significant for constructing emerging Li-ion batteries. Herein, we present a composite anode prepared using a hydrothermal method, which consists of dense NiO nanoflakes in situ growing on reduced graphene oxide (rGO) sheets. The rGO sheets within the NiO/rGO composite provide a conductive frame that enables rapid charge transfer, while the in situ anchoring of NiO nanoflakes on rGO reduces the agglomeration. We found that the appropriate loading of NiO in the composite is also significant. The NiO/rGO composite anode exhibits a high capacity of 1068 mAh g−1 after 100 cycles at 0.1 A g−1. In addition, the capacity remains 870 mAh g−1 when the current density is increased to a high rate of 2 A g−1, indicating a good rate performance for potential applications.

A bio-memristor, which was prepared using the bio-materials as basic components, has being become the focus of research owing to the potential application as medical diagnosis in biomedical field. Herein, an environmentally-friendly and sustainable bio-memristor device with Ag/walnut skin (WS)/ITO structure was fabricated, in which an obvious and reliably repeated rectangular current–voltage characteristic curve is observed. Our result shows that the WS, an useless bio-material, can be used to fabricate electronic devices after proper processing. Finally, the memory mechanism based on the conductive filament mode associated the capacitance effect is ascribed. This work has opened a new way to exploit the next generation bio-electronic device with advantages of environmentally-friendly, sustainable and pollution-free.

Recently spotlighting on lithium disulfide (Li2S2) as an intermediate product of a promising high capacity lithium–sulfur (Li S) battery, a structure of P42/mnm had been proposed for understanding the existence of Li2S2 in Li S battery. Here using first-principles unbiased CALYPSO structure searching calculations, we uncovered a new energetically favored structural phase (P21/c) of Li2S2, being more stable than the P42/mnm structure at above 2.78 GPa. This predicted P21/c structure possess a similar quasi-molecular S2 and Li atoms in the interstice of S2 with P42/mnm structure, but having a denser polyhedral packing (LiS6) with Li atoms six-fold coordination in contract to the four-fold coordinated LiS4 polyhedron of P42/mnm. Further, a calculated discharge voltage of 2.34 V was obtained for 2Li+ + 2e− + Li2S2 →2Li2S and comparable to that of P42/mnm. Adopting CI-NEB method, we calculated the diffusion barrier and diffusion coefficient of Li ions with a high diffusion coefficient of 5.98 × 10−2/cm2 s−1. This character reflects that it can acts as an intermediate product like as P42/mnm in a Li S battery. This work has a value in exposing the pressure–induced phase of Li2S2 and enriching the views for understanding in Li S batteries.

Photo-induced novel effect in a material with multiple physical properties has highly important potential applications in the photo-electric multifunctional electronic devices. In this work, the BiFeO3/ZnO bilayer films were sequentially prepared by magnetron sputtering method, which displays an obvious photo-modulated conversion between resistive switching (RS) memory and negative differential resistance (NDR) effect. Through theoretical analysis and simulation calculation, suggesting the NDR effect can be attributed to the inner electric field and the efficiently separated photogenerated electrons and holes under light-irradiation in the interface of the BiFeO3/ZnO p–n heterojunctions, while the RS memory behavior can be attributed to the formation of oxygen vacancies assisted Ag conductive filaments. This work opens up a new way to preparation a multifunction electronic device with photo-modulated conversion between RS memory and NDR effect for potential applications in optical electrical bifunctional devices, electronic information and optical quantum computers, and so on.

NiO nanostructures and film were deposited on Cu foil using radiofrequency (RF) magnetron sputtering with oblique and glancing angle deposition technology. The modified CU foil was used as an anode material for a Li ion battery without binder or conductive additives. The electrochemical properties of the NiO electrodes depended on their porosity, which varied with the angle of incidence of the target with respect to the normal substrate surface. The NiO electrodes showed a well aligned nanorod structure when deposited at a glancing angle of 85°. The optimal NiO nanorod electrodes exhibited a reversible lithium capacity of 710 mAh g−1 at a current rate of 0.5C and 270 mAh g−1 at a current rate of 20 C. Furthermore, after 1000 ultra-long cycles at 2.0C, the capacity of the NiO nanorod electrode was retained at about 500 mAh g−1, which was ~ 70% of theoretical capacity. The high performance and ultra-long life cycle of the NiO nanorod electrodes was attributed to super-structures with macroporosity.

Ultra-flexible egg albumen paper with a permittivity of 15–21, which is an improvement of nearly 300% compared with native egg albumen, is synthesized. Wearable protein-based memristor arrays exhibit excellent memory behavior and memory logic gate functionality under dual photoelectric control.

A new type of memristive memory device with an edible garlic-constructed Ag/garlic/fluorine-doped SnO2 (FTO) structure for analog neuromorphic sensor applications was designed. The memristive device shows stable memory behavior with good retention and endurance (over ∼3.0 × 104 s). These memristive properties, which can be induced through acid and alkali ion manipulation by pH modulation, are reported here for the first time. To clarify the pH-controlled memristive mechanism, conduction current fitting was applied and, meanwhile, an internal ion distribution model in the active allicin layer was proposed to explain the origin of the current variation. The pH-controlled manipulation is an efficient method to modify the memristive behavior, and this investigation also provides a potential application in terms of performing neuron functions.

Despite much progress in the semiconductor-integrated circuit technology for resistive switching memory, it is still hard to implement on the extremely complex neuromorphic networks. Resistive switching memory with multilevel operations and multi-state behaviors shows its inherent potential in neural networks. Herein, a resistive switching memory device with the structure of Ag/(C7H7O4N)n/F-doped SnO2 (FTO) showed a unique capacitance effect and negative differential resistance (NDR) states; also, a non-zero-crossing hysteresis loop and multistate resistances in terms of programming and erasing processes were feasible. Uniquely, a pH-controlled behavior was observed for the first time during the self-colored switching layer of (C7H7O4N)n extracted from a lichen plant. The chemical potential gradients generating an emf in the interfaces were responsible for this effect, and the ion transportation in the switching layer and the related redox reaction under the bias voltage played dominant roles in the multi-state memory behaviors and remarkable NDR states. This device provides a promising application in the neuromorphic artificial synapse as well as a selection of memory states.

The ever-growing demand for sustainable and renewable power sources has led to the development of novel materials for photocatalytic water splitting, but enhancing the photocatalytic efficiency remains a core problem. Herein, we report a conceptual effective and experimental confirmed strategy for SnO2 quantum dot (QD) interspersed multiphase (rutile, anatase) TiO2 nanorod arrays (SnO2/RA@TiO2 NRs) to immensely enhance the carrier separation for highly efficient water splitting by merging simultaneously the QD, multiphase, and heterojunction approaches. Under this synergistic effect, a doping ratio of 25% SnO2 QD interspersed into multiphase TiO2 NRs exhibited a superior optical adsorption and excellent photocurrent density (2.45 mA/cm2 at 1.0 V), giving rise to a largely enhanced incident light to current efficiency in the UV region (45-50%). More importantly, this material-based device can act as power supply with a voltage of ∼2.8 V after illumination, which can automatically self-recharge by reacting with oxygen vacancy and water molecule to realize reuse. The current study provides a new paradigm about heightening the carrier separation extent of QD interspersed multiphase heterojunctions, fabricating a new solar-energy-converting material/device, and achieving a highly photocatalytic water splitting/self-charging battery-like application.

Using biomaterial-constructed resistive switching memory devices has attracted great attention for the potential application in advanced electronic components because of their variety of advantages, such as low cost, sustainability, environment-friendly, and so on. In this work, after a series of treatments, an edible mushroom as an intermediate insulating material was assembled into an Ag/biofilm/metal structure, in which the metals such as Al, Cu, Ag, and Ti were chosen as the bottom electrode to explore in-depth physical mechanisms. The transmission mechanism of resistive switching memory behavior in an Ag/biofilm/metal device was studied in detail. It was found that the redox of hydroxyl-assisted Ag filaments could be easily formed on an inactive metal bottom electrode through the mushroom film by redox reaction under applied voltage. This work provides an ingenious potential application in wearable, flexible, sustainable, and environment-friendly biologically resistive random-access memories.

High-energy-density secondary batteries are required for many applications such as electric vehicles. Lithium-sulfur (Li-S) batteries are receiving broad attention because of their high theoretical energy density. However, the large volume change of sulfur during cycling, poor conductivity, and the shuttle effect of sulfides severely restrict the Li-storage performance of Li-S batteries. Herein, we present a novel core-shell nanocomposite consisting of a sulfur core and a hydrogel polypyrrole (PPy) shell, enabling an ultra-high sulfur content of about 98.4% within the composite, which greatly exceeds many other conventional composites obtained by coating sulfur onto some hosts. In addition, the void inside the core-shell structure effectively accommodates the volume change; the conductive PPy shell improves the conductivity of the composite; and PPy is able to adsorb polysulfides, suppressing the shuttle effect. After cycling for 200 cycles, the prepared S@void@PPy composite retains a stable capacity of 650 mAh g-1, which is higher than the bare sulfur particles. The composite also exhibits a fast Li ion diffusion coefficient. Furthermore, the density functional theory calculations show the PPy shell is able to adsorb polysulfides efficiently, with a large adsorption energy and charge density transfer.

The content of volatile organic compounds (VOCs) in the atmosphere will endanger the health and safety of human beings which makes it very important to develop a simple and rapid method for the determination of gas pollutants. Based on this, a new type of gas sensor was proposed for the detection of trichloroethylene in air. PEG200/ZnO nanocomposite were prepared by hydrothermal method. The materials were characterized by scanning electron microscope, X-ray energy spectrum and fourier infrared spectrum. The high selectivity of the materials was verified by using the cataluminescence (CTL) intensity of 9 kinds of VOCs on the surface of the materials as a reference. The results show that trichloroethylene can produce CTL response on the surface of PEG200/ZnO nanocomposite. Temperature, air flow rate and detector concentration all have certain effects on the CTL intensity. By comparing the CTL intensity under different reaction conditions, it is found that the suitable temperature and air flow rate are 120 °C, 180 mL/min and there is a good linear relationship between the relative CTL intensity and the concentration of the detected substance (y = 28.588 x - 285.56, R=0.9593). The gas sensor has the advantage of rapid response, and trichloroethylene can produce the maximum CTL on the surface of the material within 3 ~ 5 s.

The resistance change of an insulator or semiconductor under applied current or voltage is defined as resistive switching effect, which is a significative physical performance in the exploit of new concept nonvolatile resistance random access memory (RRAM). In our work, the g-C3N4 powder was firstly fabricated by calcination method, and continuously a device with Ag/g-C3N4/FTO structure was prepared using drop-coated g-C3N4 powder to form a film onto FTO. It can be observed that the as-prepared cell exhibits an excellent resistive switching memory characteristic (HRS/LRS resistance ratio can be reached to ~ 52) and good reliability under applied voltage window of 4.0 V. Finally, it is believed that the space charge limited conduction is appropriate to understanding such the memory behavior.

The mechanism of resistance switching memory effect has always been a focused scientific topic. In this work, a new resistance conversion mechanism is put forward in a resistance switching device with sandwich structure, in which the Cu2ZnSnSe4 (CZTSe) is used as active layer and the F-doped SnO2 (FTO) and Al-doped ZnO (AZO) acts the top and bottom electrode, respectively. Through further in-depth study, an optimal memory effect in the FTO/CZTSe/AZO device is observed when the thickness of CZTSe film is ∼200 nm (dCZTSe = 200 nm). Finally, the memory characteristics of the resistance switching device is clarified in detail by using a physical model based on the tunneling of carrier at the Schottky barrier which are formed on the FTO/CZTSe and CZTSe/AZO interfaces.

The memory device based on biomaterials is of great value in future applications because the biomaterials are environment-friendly, renewable and pollution-free. In this work, natural biomaterials, which were firstly extracted and processed from orange peel, were used as an active layer for fabricating an environment-friendly and sustainable nonvolatile memory device with Ag/Orange peel/FTO sandwich structure. An obvious memory behavior with reproducible bipolar resistive switching memory performance and large resistive storage window has been observed. This work reveals that the orange peel is a promising material for fabricating an environment-friendly and sustainable memory device in nonvolatile memory applications.

Resistance random access memory (RRAM) is a promising memory technology in the applications of memory device. Herein, the amorphous TiO2 thin film was grown onto titanium (Ti) foil by anodic oxidation. Further, the Ag/TiO2/Ti sandwich structure device was prepared, which displays a resistive switching memory effect with a high HRS/LRS resistance ratio with ∼27 at room temperature when the TiO2 film was oxidized ∼5 min. Finally, the formation/rupture models of Ag conductive filaments are suggested to explain the resistive switching memory behavior. This work open a new way for preparing the RRAM device for memory applications in the future.

The resistance random access memory (RRAM) based on biomaterials has great potential application in the sustainable electronic devices with the advantages of being sustainable, green, and environment-friendly, and it can offer a potential route for developing bio-RRAM devices, which would be a competitive bench in development of multipurpose memory devices. In our work, the banana peel, an ubiquitous useless waste, is introduced as an intermediate insulating material to preparing resistive switching memory device with Ag/Banana peel/Ti structure, in which the superior switching memory performance with a lager high resistance state/low resistance state resistance ratio and long retention characteristics are revealed. Moreover, the coexistence of memristor effect, capacitance effect, and negative differential resistance phenomenon are observed in our device. The repeatable nonvolatile resistive switching memory behaviors are attributed to the redox properties of metal cations contained in biomaterials.

The resistive switching effect is a fascinating physical phenomenon in the development of next-generation nonvolatile memory devices. In this work, the resistive switching memory behaviors of metal/In2S3/Mo/glass devices have been investigated. We observed that the top electrode materials can affect the resistive switching memory behaviors of such devices. We have also found that the devices represent an outstanding memory behavior with the largest HRS/LRS resistance ratio (storage window) when using Au as the top electrode.

In this work, a flexible resistive switching memory device based on ZnO film was fabricated using a foldable Polyethylene terephthalate (PET) film as substrate while Ag and Ti acts top and bottom electrode. Our as-prepared device represents an outstanding nonvolatile memory behavior with good "write-read-erase-read" stability at room temperature. Finally, a physical model of Ag conductive filament is constructed to understanding the observed memory characteristics. The work provides a new way for the preparation of flexible memory devices based on ZnO films, and especially provides an experimental basis for the exploration of high-performance and portable nonvolatile resistance random memory (RRAM).

In this work, a resistive switching memory device, in which niobium (Nb) inserted into magnesium diboride (MgB2) multilayer constructed heterojunctions, was prepared by vacuum sputtering at 400 °C. Furthermore, a continuously enlarge memristor memory effect was observed in Ti/(MgB2/Nb)n/MgB2/Ti (n = 0, 1, 2, 3) devices with the increasing of the inserted Nb layers numbers for the first time. Finally, a model of Schottky barrier based on interfaces of Ti/MgB2 and Nb/MgB2 are used to explain the memory characteristics.

The recent discovery of non-volatile resistive-switching memory is a promising phenomenon for the semiconductor industry and electronic device technology. In our work, CaWO4 nanoparticles were synthesised through a one-step hydrothermal reaction. A resistive-switching memory device with Ag/CaWO4/fluorine-doped tin oxide structure was prepared. This device presents photo-induced multiple-state memory behaviour at room temperature. This study is valuable for exploring multi-functional materials and their applications in photo-controlled multiple-state non-volatile memories.

In this work, the Cu(In1-xGax)Se2 (CIGS), Al doped ZnO (AZO) and Mo has been used for constructing a resistive switching device with AZO/CIGS/Mo sandwich structure grown on a transparent glass substrate. The device represents a high-performance memory characteristics under ambient temperature. In particularly, a resistance ratio change phenomenon have been observed in our device for the first time.

Advanced rechargeable Na-ion battery is favored by researchers owing to its relatively low-priced and earth-abundant resource. In this work, BiFeO3 nanoflakes by compositing with organic pectin as an outstanding anode material for rechargeable Na-ion batteries were fabricated by an improved hydrothermal process for the first time. We found that the BiFeO3/pectin nanoflakes as anode hold long life and excellent charge–discharge performance with reversible capacity of 450 mAh g–1, which can retain 100% capacity after 100 charge–discharge cycles. It is inferred that the excellent performance of Na-ion batteries is contributed to viscoelastic pectin among BiFeO3 crystal lattices. The organic pectin can play a buffer role in the process of BiFeO3 crystal lattices expansion when Na ions inserted, indicating the BiFeO3/pectin nanoflakes are not easily degenerated as anode in Na-ion battery. This work provides great potential for fabricating low-priced and high power density Na-ion batteries for electronic equipm...

In this work, the resistive switching mechanism of metal/MoS 2 /Ti/Si devices with different metal acts top electrode materials have been investigated. The device represents an outstanding memory behavior with larger storage window when using Ag acts top electrode. This work reveals that Ag filaments can be easily formed by redox process in MoS 2 film.

High-polluting industrial ammonia synthesis runs counter to the intentions of a low-carbon society. In contrast, the electrocatalytic nitrogen reduction reaction (NRR) is expected to provide fascinating and broad prospects for green ammonia synthesis, which urgently requires efficient and low-cost catalysts. Although it has been proven that two-dimensional (2D) transition metal carbides and carbonitrides (MXenes) have great potential for NRR, there is still need to further improve their activity. In this work, a co-doping strategy was employed to design the electronic configuration and structural mechanic of Ti3C2Tx catalysts for efficient NRR. As expected, the synergistic effect of N and S dopants in Ti3C2Tx (NS-Ti3C2Tx) significantly improves the electron/ion transport capacity and increases the catalytic active sites. Specifically, the as-prepared NS-Ti3C2Tx nanosheets demonstrated an excellent electrocatalytic stability with NH3 yield of 34.23 μg h−1 mg−1cat at −0.55 V vs. RHE, and a Faraday efficiency of 6.6% in 0.05 M H2SO4. Therefore, this work opens up a new research approach for preparing high-performance catalysts for energy storage applications through efficient nitrogen fixation technology.

In this work, hexagonal MoSe2 nanosheets were prepared by hydrothermal process. Next, the resistive switching memory behaviour of single MoSe2 nanosheets was further investigated. We observed that MoSe2 nanosheets based memory device show reproducible and stable bipolar resistive switching memory characteristics. Through the analysis for conductive mechanism, the formation and rupture of nanoscale Ag filament inside the MoSe2 nanosheets is suggested to explain the memory behaviour.

In this work, the MoSe 2 nanosheets were firstly prepared by hydrothermal method. We found the magnetism of MoSe 2 nanosheets obviously enhance with the decrease of temperature. Further, we fabricated a memristor using as-prepared MoSe 2 nanosheets, and observed temperature can regulate the memristor memory behavior of the device. In a word, this work reveals the potential multifunctional applications of MoSe 2 nanosheets with magnetism and memristive memory effects in future device technology.

A simple sol-gel method with butterfly as a biotemplate to prepare Li 4 Ti 5 O 12 -TiO 2 (LTO-TiO 2 ) nanostructures is presented in this study. Results show that the LTO-TiO 2 has a periodical 3-dimension (3D) nanostructure, and delivers a high reversible capacity of 169 mAh/g and nearly 100% capacity retention over 80 charge-discharge cycles. Furthermore, LTO-TiO 2 nanostructures exhibit an excellent rate capability of 56 mAh/g at 20 C. It is believed that the high performance of the anode materials can be attributed to the high surface area and perfect electron transport channels of 3D periodical nanostructures. We firmly believe that this work hold great promise for providing a perfect reference for artificially synthesized micro-nanostructure materials.

Composite particles (CPs) with an average diameter of 100 gm, containing the amorphous silicates, but crystal structures are dominated by the NaS2, Al2S3, Al0.55Mo2S4 and MoO3, are synthesized using hydrothermal method. Bipolar resistive switching (RS) memory behaviors with favorable resistance ON/OFF ratio, high retention and voltage cycling endurance performance are observed in the CPs-based device. The RS memory behaviors can be well controlled by stressing visible light at room temperature. The traps/deep traps based physical modes are proposed to interpret the RS memory behaviors for the quasi-bulk silicate-based composites. Different from conventional nano-scale RS memory device, the discovery of the RS memory behavior of micro-scale silicate composites may provide one new insight into the mechanism of resistive switching behavior. (C) 2017 Published by Elsevier Ltd.

Resistive random access memory (RRAM) devices have emerged as promising candidates for near future nonvolatile information storage. Eggshells, a food waste, have not been focused and recycled sustainably today. Eggshell-based devices have shown a large resistive-switching(RS) memory behaviors with favorable resistance ratio of ∼10 3 , larger memory window of ∼3.5 V, and high endurance and retention performance. Redox-based Ag filament models involving the formation and rupture of the metallic conduction filaments between top and bottom electrodes are proposed to interpret the large nonvolatile bipolar RS memory behaviors. This discovery provides for the possibility of an environmentally friendly, low-cost and sustainable material application in the next-generation nonvolatile date storage device.

Potential Sm1−xCaxBiO3 (x = 0.1, 0.2, 0.3, and 0.4) buffer layers for REBa2Cu3O7−x(REBCO, RE = Y or Nd, Sm, Gd, Dy, etc) coated conductors (CCS) has been deposited on (00l) LaAlO3 substrate via a self-developed polymer-assisted chemical solution deposition (PA-CSD) route, and then studied by XRD, SEM, AFM and current-voltage (I–V) characteristics. Highly c-axis oriented, dense, smooth and crack-free buffer layers have been obtained. We found that its resistivity does not decrease obviously. The pseudo-cubic lattice parameter of Sm1−xCaxBiO3 matches well with the in-plan lattice parameters of corresponding REBCO compounds. YBCO superconducting epitaxial film with high performance is successfully deposited on Sm0.6Ca0.4BiO3 layer by dc sputtering. Our results offer a new avenue to search for better lattice matched buffer layer for CCS, particularly to REBCO.

Memristors possess great application prospects in terabit nonvolatile storage devices, memory-in-logic algorithmic chips and bio-inspired artificial neural network systems. However, "what is the origin state of the memristor?" has remained an unanswered question for half a century. While many applications rely on the memristor, its origin state is becoming a fundamental issue. Herein, we reveal a new state, the pure capacitance state (PCS), which occurs before the memristor is triggered, and the origin state of the memristor can be verified in the memory cells through controlling the ambience parameters. Discovery of the PCS, a missing earlier stage of the memristor, completes the whole evolution map of the memristor from the very beginning to the final developed state.

Capacitive devices have drawn a beautiful application scene in electronic device systems ranging from touch sensors, energy storages and multifunction transistors, but serving as memristive term is still blank. Sweet potato peel (SPP) as function layer was employed to develop the memristive device with Ag/SPP/F-doped SnO2 (FTO) structure. A current-voltage (I-V) hysteresis, which is characterized by a typical capacitive behavior, is impressively observed in the developed device. Nonvolatile data storage is feasible using the non-zero-crossing I-V hysteresis because the resistance states can be well maintained. Charge transfer at the Ag/SPP and SPP/FTO interfaces, and the interplay between Ag+ ions and charges are responsible for this non-zero-crossing I-V hysteresis behaviors. This work possibly gives an insight into the data storage in terms of a new conception electronic device based on environment-friendly material.

It is well know that the high temperature annealing can improve the permeability and reduce the hysteresis loss of soft magnetic composites (SMCs), but the eddy current loss would be accordingly increased. Thus, developing SMCs with high permeability and low core loss remains a challenge. Herein, we prepared a kind of Fe/Fe3O4-FeSiAl soft magnetic composites by replacing some Fe powders with FeSiAl, possessing high permeability and low core loss. In the fabricating process, reduced iron powders were coated with a FexOy insulating layer by surface oxidation method and the Fe/FexOy and FeSiAl alloy powders were used as raw materials to fabricate Fe/FexOy and Fe/FexOy-FeSiAl SMCs. Moreover, the optimum content of FeSiAl powders and the effects of high temperature annealing on the structure and performance of Fe/FexOy and Fe/FexOy-FeSiAl SMCs was investigated. These results of XRD, XPS and FTIR showed the Fe2O3 and Fe-OH existing in the FexOy insulating coating is gradually transformed to Fe3O4 under annealed at 550 ℃, and the permeability and eddy current loss were greatly increased for Fe/FexOy SMCs. However, the permeability was highly increased but the eddy current loss stay unchangeable for Fe/FexOy-FeSiAl SMCs. These results strongly demonstrated the Fe/Fe3O4-FeSiAl SMCs have high permeability and low core loss. Keywords: Soft magnetic composites, Surface oxidation, High permeability, Low core loss

The concept of the memristor, a resistor with memory, was proposed by Chua in 1971 as the fourth basic element of electric circuitry. Despite a significant amount of effort devoted to the understanding of memristor theory, our understanding of the nonpinched current–voltage (I–V) hysteresis loop in memristors remains incomplete. Here we propose a physical model of a memristor, with a capacitor connected in parallel, which explains how the nonpinched I–V hysteresis behavior originates from the capacitive-coupled memristive effect. Our model replicates eight types of characteristic nonlinear I–V behavior, which explains all observed nonpinched I–V curves seen in experiments. Furthermore, a reversible transition from a nonpinched I–V hysteresis loop to an ideal pinched I–V hysteresis loop is found, which explains the experimental data obtained in C15H11O6-based devices when subjected to an external stimulus (e.g., voltage, moisture, or temperature). Our results provide the vital physics models and materials ...

The large-scale crossbar array is a promising architecture for hardware-amenable energy efficient three-dimensional memory and neuromorphic computing systems. While accessing a memory cell with negligible sneak currents remains a fundamental issue in the crossbar array architecture, up-to-date memory cells for large-scale crossbar arrays suffer from process and device integration (one selector one resistor) or destructive read operation (complementary resistive switching). Here, we introduce a self-selective memory cell based on hexagonal boron nitride and graphene in a vertical heterostructure. Combining non-volatile and volatile memory operations in the two hexagonal boron nitride layers, we demonstrate a self-selectivity of 1010 with an on/off resistance ratio larger than 103. The graphene layer efficiently blocks the diffusion of volatile silver filaments to integrate the volatile and non-volatile kinetics in a novel way. Our self-selective memory minimizes sneak currents on large-scale memory operation, thereby achieving a practical readout margin for terabit-scale and energy-efficient memory integration., Designing large-scale crossbar arrays for energy efficient neuromorphic computing systems remains a challenge. Here, the authors propose Van der Waals (h-BN/graphene/h-BN) self-selective memory design able to combine, in the same cell, non-volatile and volatile behaviors with negligible sneak current.

With the memory device is required to be widely used in more complex environment, the exploration of new memory device have become a focus of research. Herein, a resistive switching memory device based on BiFeO3(BFO)/Cu2ZnSnSe4(CZTSe) heterostructure is demonstrated, further the resistive switching characteristics of as-prepared device are characterized under different testing environments, suggesting an environmental factors controlled memory behavior is observed. Finally, we propose a new mechanism to explain the resistive switching effect based on the tunneling of interfacial carriers induced filament formation. This work demonstrates that the resistive switching memory device constructed by advanced semiconductor heterostructure display superior application value because they can work in complex environments. Keywords: Resistance switching, Heterojunction, BiFeO3, Cu2ZnSnSe4, Environmental factors, Memory device