scholarly journals WO3Nanowires on Graphene Sheets as Negative Electrode for Supercapacitors

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Bo Liu ◽  
Yan Wang ◽  
Hong-Wu Jiang ◽  
Ben-Xue Zou

WO3nanowires directly grown on graphene sheets have been fabricated by using a seed-mediated hydrothermal method. The morphologies and electrochemical performance of WO3films prepared by different process were studied. The results show that the precoated nanoseeds and graphene sheets on graphite electrode provide more reactive centers for the nucleation and formation of uniform WO3nanowires. The WO3nanowires electrode exhibits a high area specific capacitance of 800 mF cm−2over negative potential range from −1.0 V to 0 V versus SCE in 1 M Li2SO4solution. A high performance electrochemical supercapacitor assembled with WO3nanowires as negative electrode and PANI/MnO2as positive electrodes over voltage range of 1.6 V displays a high volumetric capacitance of 2.5 F cm−3, which indicate great potential applications of WO3nanowires on graphene sheets as negative electrode for energy storage devices.

Nanomaterials ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 340 ◽  
Author(s):  
Yuanwei Li ◽  
Xueyang Zhao ◽  
Hui Liu ◽  
Wei Li ◽  
Xiaojian Wang

In this paper, nanoporous copper (NPC) was prepared by dealloying ZrCuAl metallic glass ribbons with HF acid solutions. The effect of dealloying time on the porous structures and thickness of the obtained NPC films was investigated. It was found that the ligament sizes of the NPC could be tuned in a range from 20 to 300 nm, and the thicknesses of the NPC films from 3.1 to 14.4 μm, with properly selected dealloying times. Furthermore, nanoporous composites made of NPC and nanoporous Cu2O were prepared by oxidizing the NPC with ethanol. The nanoporous composite electrodes exhibited superior charge-discharge performance and would have broad potential applications in flexible high-performance energy storage devices.


Author(s):  
Anil Kumar Yedluri ◽  
Hee-Je Kim

CoO-ZnO-based composites have attracted considerable attention for the development of energy storage devices because of their multifunctional characterization and ease of integration with existing components. This paper reports the synthesis of CoO@ZnO (CZ) nanostructures on Ni foam by the CBD method for facile and eco-friendly supercapacitor applications. The formation of a CoO@ZnO electrode functioned with cobalt, zinc, nickel and oxygen groups was confirmed by X-ray diffraction, X-ray photoelectron spectroscopy, low and high-resolution of scanning electron microscopy, and transmission electron microscopy. The as-synthesized hierarchical nanocorn skeleton-like structure of CoO@ZnO-3h (CZ3h) electrode delivered a higher specific capacitance of 1136 F/g at a current density of 3 A/g with outstanding cycling stability, showing 98.3% capacitance retention over 3000 cycles in an aqueous 2 M KOH electrolyte solution. This retention was significantly better than that of other prepared electrodes, such as CoO (CO), ZnO (ZO), CoO@ZnO-1h (CZ1h), and CoO@ZnO-7h (CZ7h) (274, 383, 240 and 537 F/g, respectively). This superior capacitance was attributed to the ideal surface morphology of CZ3h, which is responsible for the rapid electron/ion transfer between the electrolyte and electrode surface area. The enhanced features of the CZ3h electrode highlight potential applications in high performance supercapacitors, solar cells, photocatalysis, and electrocatalysis.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kentaro Ogata ◽  
Yusuke Nakayama ◽  
Gang Xiao ◽  
Hideo Kaiju

AbstractMagnetic tunnel junctions (MTJs) in the field of spintronics have received enormous attention owing to their fascinating spin phenomena for fundamental physics and potential applications. MTJs exhibit a large tunnel magnetoresistance (TMR) at room temperature. However, TMR depends strongly on the bias voltage, which reduces the magnitude of TMR. On the other hand, tunnel magnetocapacitance (TMC), which has also been observed in MTJs, can be increased when subjecting to a biasing voltage, thus exhibiting one of the most interesting spin phenomena. Here we report a large voltage-induced TMC beyond 330% in MgO-based MTJs, which is the largest value ever reported for MTJs. The voltage dependence and frequency characteristics of TMC can be explained by the newly proposed Debye-Fröhlich model using Zhang-sigmoid theory, parabolic barrier approximation, and spin-dependent drift diffusion model. Moreover, we predict that the voltage-induced TMC ratio could reach over 3000% in MTJs. It is a reality now that MTJs can be used as capacitors that are small in size, broadly ranged in frequencies and controllable by a voltage. Our theoretical and experimental findings provide a deeper understanding on the exact mechanism of voltage-induced AC spin transports in spintronic devices. Our research may open new avenues to the development of spintronics applications, such as highly sensitive magnetic sensors, high performance non-volatile memories, multi-functional spin logic devices, voltage controlled electronic components, and energy storage devices.


Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 270
Author(s):  
Syed Shaheen Shah ◽  
Himadri Tanaya Das ◽  
Hasi Rani Barai ◽  
Md. Abdul Aziz

Energy generation can be clean and sustainable if it is dependent on renewable resources and it can be prominently utilized if stored efficiently. Recently, biomass-derived carbon and polymers have been focused on developing less hazardous eco-friendly electrodes for energy storage devices. We have focused on boosting the supercapacitor’s energy storage ability by engineering efficient electrodes in this context. The well-known conductive polymer, polyaniline (PANI), deposited on nickel foam (NF) is used as a positive electrode, while the activated carbon derived from jute sticks (JAC) deposited on NF is used as a negative electrode. The asymmetric supercapacitor (ASC) is fabricated for the electrochemical studies and found that the device has exhibited an energy density of 24 µWh/cm2 at a power density of 3571 µW/cm2. Furthermore, the ASC PANI/NF//KOH//JAC/NF has exhibited good stability with ~86% capacitance retention even after 1000 cycles. Thus, the enhanced electrochemical performances of ASC are congregated by depositing PANI on NF that boosts the electrode’s conductivity. Such deposition patterns are assured by faster ions diffusion, higher surface area, and ample electroactive sites for better electrolyte interaction. Besides advancing technology, such work also encourages sustainability.


2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Zhemi Xu ◽  
Adnan Younis ◽  
Dewei Chu ◽  
Zhimin Ao ◽  
Haolan Xu ◽  
...  

Metal oxide nanosheets have promising potential applications in novel energy storage devices. In this work, Co3O4nanosheets/carbon foam with excellent supercapacitor characteristics was successfully fabricated, without using metal substrates. The experimental results demonstrate that the electrochemical tests showed that the as-prepared Co3O4nanosheets exhibited an ideal capacitive behavior with a maximum specific capacitance of 106 F/g in 1 M NaOH solution at a scan rate of 0.1 V s−1.


Ionics ◽  
2021 ◽  
Author(s):  
Morteza Saghafi Yazdi ◽  
Seied Ali Hosseini ◽  
Zeynodin Karami ◽  
Ali Olamaee ◽  
Mohammad Abedini ◽  
...  

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 372
Author(s):  
Liyang Lin ◽  
Susu Chen ◽  
Tao Deng ◽  
Wen Zeng

The metal oxides/graphene nanocomposites have great application prospects in the fields of electrochemical energy storage and gas sensing detection. However, rational synthesis of such materials with good conductivity and electrochemical activity is the topical challenge for high-performance devices. Here, SnO2/graphene nanocomposite is taken as a typical example and develops a universal synthesis method that overcome these challenges and prepares the oxygen-deficient SnO2 hollow nanospheres/graphene (r-SnO2/GN) nanocomposite with excellent performance for supercapacitors and gas sensors. The electrode r-SnO2/GN exhibits specific capacitance of 947.4 F g−1 at a current density of 2 mA cm−2 and of 640.0 F g−1 even at 20 mA cm−2, showing remarkable rate capability. For gas-sensing application, the sensor r-SnO2/GN showed good sensitivity (~13.8 under 500 ppm) and short response/recovering time toward methane gas. These performance features make r-SnO2/GN nanocomposite a promising candidate for high-performance energy storage devices and gas sensors.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jing Hu ◽  
Xiaomin Tang ◽  
Qing Dai ◽  
Zhiqiang Liu ◽  
Huamin Zhang ◽  
...  

AbstractMembranes with fast and selective ions transport are highly demanded for energy storage devices. Layered double hydroxides (LDHs), bearing uniform interlayer galleries and abundant hydroxyl groups covalently bonded within two-dimensional (2D) host layers, make them superb candidates for high-performance membranes. However, related research on LDHs for ions separation is quite rare, especially the deep-going study on ions transport behavior in LDHs. Here, we report a LDHs-based composite membrane with fast and selective ions transport for flow battery application. The hydroxide ions transport through LDHs via vehicular (standard diffusion) & Grotthuss (proton hopping) mechanisms is uncovered. The LDHs-based membrane enables an alkaline zinc-based flow battery to operate at 200 mA cm−2, along with an energy efficiency of 82.36% for 400 cycles. This study offers an in-depth understanding of ions transport in LDHs and further inspires their applications in other energy-related devices.


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