Unveiling the redox electrochemistry of 1D,urchin-like vanadium sulfide electrodes for high-performance hybrid supercapacitors

Exploring novel versatile electrode materials with outstanding electrochemical performance is the key to the development of advanced energy conversion and storage devices.In this work,we aim to construct new-fangled one-dimensional(1D)quasi-layered patronite vanadium tetrasulfide(VS_(4))nanostructures by using different sulfur sources,namely thiourea,thioacetamide,and L-cysteine through an ethyleneaminetetraacetic-acid(EDTA)-mediated solvothermal process.The as-prepared VS4exhibits several unique morphologies such as urchin,fluffy nanoflower,and polyhedron with appropriate surface areas.Among the prepared nanostructures,the VS_(4)-1@NF nanostructure exhibited excellent electrochemical properties in 6 M KOH solution,and we explored its redox electrochemistry in detail.The asprepared VS_(4)-1@NF electrode exhibited battery-type redox characteristics with the highest capacity of280 C g^(-1)in a three-electrode assembly.Moreover,it offered a capacity of 123 F g^(-1)in a hybrid twoelectrode set-up at 1 A g^(-1)with the highest specific energy and specific power of 38.5 W h kg^(-1)and750 W kg^(-1),respectively.Furthermore,to ensure the practical applicability and real-world performance of the prepared hybrid AC@NF//VS_(4)-1@NF cell,we performed a cycling stability test with more than 5,000galvanostatic charge–discharge cycles at 2 A g^(-1),and the cell retained around 84.7%of its capacitance even after 5,000 cycles with a CE of 96.1%.

Current innovations and future prospects of metal oxide electrospun materials for supercapacitor technology:A review

Metal oxides with one-dimensional(1-D)nanostructures have shown promise as electrode materials for supercapacitors due to their unique properties,such as high aspect ratio,increased interaction between electrode and electrolyte,favourable mechanical strength,and short ion transportation pathways that im-prove the charge-discharge rates of electrons and ions.Electrospinning is an effective technique for cre-ating 1-D metal oxide nanostructures that produce highly porous nanofibrous structures with exceptional specific surface areas,predictable pore size distributions,and tunable interconnected porosity.This paper provides a comprehensive review of the literature on electrospun metal oxide nanostructures for superca-pacitors,including the principles and key parameters of electrospinning,an overview of supercapacitors,the charge storage mechanism of electrospun metal oxides,and recent developments in 1-D electrospun nanostructures,from binary to ternary metal oxides.The review also discusses unresolved issues and future directions in this research field.Overall,this paper offers valuable insights into the latest devel-opments,unresolved issues,and prospects of 1-D nanostructured metal oxides fabricated through elec-trospinning for supercapacitor applications,providing a critical analysis of their potential in this rapidly evolving field.

Exploring the experimental study and density functional theory calculations of symmetric and asymmetric chalcogen atoms interacted molybdenum dichalcogenides for lithium-ion batteries

Two-dimensional asymmetric chalcogen atoms attached to Janus nanoparticles have fascinated research attention owing to their distinctive properties and characteristics for various applications.This paper proposed a facile synthesis to produce efficient molybdenum-based symmetric and asymmetric chalcogens bounded by X Mo X and TeMo X nanostructures.Subsequently,the fabricated X Mo X and TeMo X nanostruc-tures were employed as anodes for lithiumion batteries(LIBs).Assembled LIBs using TeMoS and TeMoSe Janus anodes achieved 2610 and 2073 mAh g^(-1)reversible capacity at 0.1 A g^(-1),respectively for the halfcell configuration,which is outstanding performance compared with previous reports.Superior rate capability performances at 0.1-20 A g^(-1)and exceptional cycling solidity confirmed high charge and discharge capacities for TeMo X Janus lithium-ion battery anodes.In addition,the full cell device with TeMoS//LiCoO_(2)configuration explored the discharge capacity of 1605 mAh g^(-1)at 0.1 A g^(-1)which suggests their excellent electrochemical characteristics.The density functional theory approximations established the significance of assembled symmetric and asymmetric chalcogen atoms interacted with X Mo X and TeMo X anode materials for LIBs.Thus,the present investigation supports a new approach to creating two-dimensional materials based on asymmetric chalcogen atoms with core metal to effectively increase desirable energy storage characteristics.

Demonstration of synaptic and resistive switching characteristics in W/TiO_(2)/HfO_(2)/TaN memristor crossbar array for bioinspired neuromorphic computing

In this study,resistive random-access memory(RRAM)-based crossbar arrays with a memristor W/TiO_(2)/HfO_(2)/TaN structure were fabricated through atomic layer deposition(ALD)to investigate synaptic plasticity and resistive switching(RS)characteristics for bioinspired neuromorphic computing.X-ray photoelectron spectroscopy(XPS)was employed to explore oxygen vacancy concentrations in bilayer TiO_(2)/HfO_(2)films.Gaussian fitting for O1s peaks confirmed that the HfO_(2)layer contained a larger number of oxygen vacancies than the TiO_(2)layer.In addition,HfO_(2)had lower Gibbs free energy(ΔG°=-1010.8 kJ/mol)than the TiO_(2)layer(ΔG°=-924.0 kJ/mol),resulting in more oxygen vacancies in the HfO_(2)layer.XPS results andΔG°magnitudes confirmed that formation/disruption of oxygen-based conductive filaments took place in the TiO_(2)layer.The W/TiO_(2)/HfO_(2)/TaN memristive device exhibited excellent and repeatable RS characteristics,including superb 10^(3) dc switching cycles,outstanding 107 pulse endurance,and high-thermal stability(10^(4) s at 125℃)important for digital computing systems.Furthermore,some essential biological synaptic characteristics such as potentiation-depression plasticity,paired-pulse facilitation(PPF),and spike-timing-dependent plasticity(STDP,asymmetric Hebbian and asymmetric anti-Hebbian)were successfully mimicked herein using the crossbar-array memristive device.Based on experimental results,a migration and diffusion of oxygen vacancy based physical model is proposed to describe the synaptic plasticity and RS mechanism.This study demonstrates that the proposed W/TiO_(2)/HfO_(2)/TaN memristor crossbar-array has a significant potential for applications in non-volatile memory(NVM)and bioinspired neuromorphic systems.

Fundamentals and comprehensive insights on pulsed laser synthesis of advanced materials for diverse photo-and electrocatalytic applications

The global energy crisis is increasing the demand for innovative materials with high purity and functionality for the development of clean energy production and storage.The development of novel photo-and electrocatalysts significantly depends on synthetic techniques that facilitate the production of tailored advanced nanomaterials.The emerging use of pulsed laser in liquid synthesis has attracted immense interest as an effective synthetic technology with several advantages over conventional chemical and physical synthetic routes,including the fine-tuning of size,composition,surface,and crystalline structures,and defect densities and is associated with the catalytic,electronic,thermal,optical,and mechanical properties of the produced nanomaterials.Herein,we present an overview of the fundamental understanding and importance of the pulsed laser process,namely various roles and mechanisms involved in the production of various types of nanomaterials,such as metal nanoparticles,oxides,non-oxides,and carbon-based materials.We mainly cover the advancement of photo-and electrocatalytic nanomaterials via pulsed laser-assisted technologies with detailed mechanistic insights and structural optimization along with effective catalytic performances in various energy and environmental remediation processes.Finally,the future directions and challenges of pulsed laser techniques are briefly underlined.This review can exert practical guidance for the future design and fabrication of innovative pulsed laser-induced nanomaterials with fascinating properties for advanced catalysis applications.

Optimizing the thickness of Ta_(2)O_(5) interfacial barrier layer to limit the oxidization of Ta ohmic interface and ZrO_(2) switching layer for multilevel data storage

The multilevel storage capability of nonvolatile resistive random access memory(ReRAM)is greatly de-sired to accomplish high functioning memory density.In this study,Ta_(2)O_(5) thin film with different thick-nesses(2,4,and 6 nm)was exploited as an appropriate interfacial barrier layer for limiting the formation of the interfacial layer between the 10 nm thick sputtering deposited resistive switching(RS)layer and Ta ohmic electrode to improve the switching cycle endurance and uniformity.Results show that lower form-ing voltage,narrow distribution of SET-voltages,good dc switching cycles(10^(3)),high pulse endurance(10^(6) cycles),long retention time(10^(4) s at room temperature and 100℃),and reliable multilevel resis-tance states were obtained at an appropriate thickness of∼2 nm Ta_(2)O_(5) interfacial barrier layer instead of without Ta_(2)O_(5) and with∼4 nm,and∼6 nm Ta_(2)O_(5) barrier layer,ZrO_(2)-based memristive devices.Besides,multilevel resistance states have been scientifically investigated via modulating the compliance current(CC)and RESET-stop voltages,which displays that all of the resistance states were distinct and stayed stable without any considerable deprivation over 10^(4) s retention time and 104 pulse endurance cycles.The I-V characteristics of RESET-stop voltage(from−1.7 to−2.3 V)of HRS are found to be a good linear fit with the Schottky equation.It can be seen that Schottky barrier height rises by increasing the stop-voltage during RESET-operation,resulting in enhancing the data storage memory window(on/offratio).Moreover,RESET-voltage and CC control of HRS and LRS revealed the physical origin of the RS mecha-nism,which entails the formation and rupture of conducting nanofilaments.It is thoroughly investigated that proper optimization of the barrier layer at the ohmic interface and the switching layer is essential in memristive devices.These results demonstrate that the ZrO_(2)-based memristive device with an optimized∼2 nm Ta_(2)O_(5) barrier layer is a promising candidate for multilevel data storage memory applications.

WRA-Net:Wide Receptive Field Attention Network for Motion Deblurring in Crop and Weed Image

Automatically segmenting crops and weeds in the image input from cameras accurately is essential in various agricultural technology fields,such as herbicide spraying by farming robots based on crop and weed segmentation information.However,crop and weed images taken with a camera have motion blur due to various causes(e.g.,vibration or shaking of a camera on farming robots,shaking of crops and weeds),which reduces the accuracy of crop and weed segmentation.Therefore,robust crop and weed segmentation for motion-blurred images is essential.However,previous crop and weed segmentation studies were performed without considering motion-blurred images.To solve this problem,this study proposed a new motion-blur image restoration method based on a wide receptive field attention network(WRA-Net),based on which we investigated improving crop and weed segmentation accuracy in motion-blurred images.WRA-Net comprises a main block called a lite wide receptive field attention residual block,which comprises modified depthwise separable convolutional blocks,an attention gate,and a learnable skip connection.We conducted experiments using the proposed method with 3 open databases:BoniRob,crop/weed field image,and rice seedling and weed datasets.According to the results,the crop and weed segmentation accuracy based on mean intersection over union was 0.7444,0.7741,and 0.7149,respectively,demonstrating that this method outperformed the state-of-the-art methods.

Controlled multilevel switching and artificial synapse characteristics in transparent HfAlO-alloy based memristor with embedded TaN nanoparticles

Atomic layer deposition technique has been used to prepare tantalum nitride nanoparticles(TaN-NPs)and sandwiched between Al-doped HfO;layers to achieve ITO/HfAlO/TaN-NP/HfAlO/ITO RRAM device.Transmission electron microscopy along with energy dispersive spectroscopy confirms the presence of TaN-NPs.X-ray photoelectron spectroscopy suggests that part of Ta N converted to tantalum oxynitride(TaO_(x)N_(y))which plays an important role in stable cycle-to-cycle resistive switching.Charge trapping and oxygen vacancy creation were found to be modified after the inclusion of Ta N-NPs inside RRAM structure.Also,HfAlO/TaO_(x)N_(y)interface due to the presence TaN-NPs improves the device-to-device switching reliability by reducing the probability of random rupture/formation of conductive filaments(CFs).DC endurance of more than 10^(3)cycles and memory data retention up to 10^(4)s was achieved with an insignificant variation of different resistance states.Multilevel conductance was attained by controlling RESET voltage with stable data retention in multiple states.The volatile threshold switching was monitored after controlling the CF forming at 200 nA current compliance with high selectivity of~10^(3).Synaptic learning behavior has been demonstrated by spike-rate-dependent plasticity(SRDP).Reliable potentiation and depression processes were observed after the application of suitable negative and positive pulses which shows the capability of the TaN–NPs based RRAM device for transparent synaptic devices.

Mn_(3)O_(4) based materials for electrochemical supercapacitors: Basic principles, charge storage mechanism, progress, and perspectives

The captivating properties of supercapacitors(SCs) such as high power and reasonably high energy densities made them stand up as a versatile solution to emerging energy storage applications.Thus,everyone is in pursuit of improvisation of the energy storage characteristics of SCs.Hausmannite or manganese oxide(Mn_(3)O_(4)) is a widely studied electrode material considering its fascinating features such as high theoretical capacitance(1370 F/g),variable oxidization states,prominent Jahn-Teller effect,broad potential window,environmentally benign and cost-effectiveness.A lot of research has been carried out on this material to unfold and improve its electrochemical aspects.In this review,comprehensive knowledge and innovative attempts taken to improve its energy storage of Mn_(3)O_(4)material are discussed.Firstly,the basic properties concerned with electrochemical charge storage such as valance states,crystal structure,band diagram and energy storage mechanism are discussed,followed by putting forth the limitations of Mn_(3)O_(4).Later on,various strategies adopted to improve the electrochemical attributes of Mn_(3)O_(4)such as making composite with carbon-based materials,metal-based materials,polymers or doping metal atoms are thorough.Finally,remarks on key scientific points and perspectives for further development of energy storage in Mn_(3)O_(4)conclude this review.

Finger vein recognition using weighted local binary pattern code based on a support vector machine

Finger vein recognition is a biometric technique which identifies individuals using their unique finger vein patterns. It is reported to have a high accuracy and rapid processing speed. In addition, it is impossible to steal a vein pattern located inside the finger. We propose a new identification method of finger vascular patterns using a weighted local binary pattern (LBP) and support vector machine (SVM). This research is novel in the following three ways. First, holistic codes are extracted through the LBP method without using a vein detection procedure. This reduces the processing time and the complexities in detecting finger vein patterns. Second, we classify the local areas from which the LBP codes are extracted into three categories based on the SVM classifier: local areas that include a large amount (LA), a medium amount (MA), and a small amount (SA) of vein patterns. Third, different weights are assigned to the extracted LBP code according to the local area type (LA, MA, and SA) from which the LBP codes were extracted. The optimal weights are determined empirically in terms of the accuracy of the finger vein recognition. Experimental results show that our equal error rate (EER) is significantly lower compared to that without the proposed method or using a conventional method.

Dipole-assisted carrier transport in bis(trifluoromethane) sulfonamide-treated O-ReS_(2) field-effect transistor

We demonstrate the dipole-assisted carrier transport properties of bis(trifluoromethane)sulfonamide(TFSI)-treated O-ReS_(2) field-effect transistors.Pristine ReS_(2) was compared with defect-mediated ReS_(2) to confirm whether the presence of defects on the interface enhances the interaction between O-ReS_(2) and TFSI molecules.Prior to the experiment,density functional theory(DFT)calculation was performed,and the result indicated that the charge transfer between TFSI and O-ReS_(2) is more sensitive to external electric fields than that between TFSI and pristine ReS_(2).After TFSI treatment,the drain current of O-ReS_(2) FET was significantly increased up to 1,113.4 times except in the range of−0.32–0.76 V owing to Schottky barrier modulation from dipole polarization of TFSI molecules,contrary to a significant degradation in device performance in pristine ReS_(2) FET.Moreover,in the treated O-ReS_(2) device,the dipole direction was highly influenced by the voltage sweep direction,generating a significant area of hysteresis in I–V and transfer characteristics,which was further verified by the surface potential result.Furthermore,the dipole state was enhanced according to the wavelength of the light source and photocurrent.These results indicate that TFSI-treated ReS_(2) FET has large potential for use as next-generation memristor,memory,and photodetector.