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1.
Waste Manag ; 106: 250-260, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32240941

RESUMO

Here in this work, porous carbon is prepared from waste of a traditional Chinese medicine Salvia miltiorrhiza flowers. Structures of the porous carbons are regulated by simply regulating of activation temperatures and dosages of activator. The optimized porous carbon owns a high specific surface area of 1715.3 m2 g-1 and total pore volume of 0.6392 cm3 g-1, together with a unique hierarchical architecture and ultrahigh content of 45.97 at% self-doped O and 0.49 at% of N. When used as electrode materials for supercapacitors, the prepared porous carbon exhibited excellent specific capacitance and energy density as well as fantastic cycle stability. Under a current density of 0.5 A/g, the electrode based on this material showed high specific capacitance of 530 F/g, with fantastic rate performance of 258 F/g at 20 A/g and excellent cycle stability of 91% capacitance retention for 10,000 cycles at 10 A/g in a three-electrode system in 6 M KOH. In assembled supercapacitors, the SF-PC700-3 based electrode worked under potential of 1 V and exhibited 222 F/g of specific capacitance at a current density of 0.5 A/g, and even when the current density was increased up to 30 A/g, the specific capacitance can still as high as 168 F/g, verified the excellent performance of SF-PC700-3. Symmetric supercapacitors in Na2SO4 and TEABF4/AN electrolyte showed voltage ranges of 1.8 V and 3 V respectively, and high energy density of 22.2 Wh Kg-1 at 448. W Kg-1 and 40.6 Wh Kg-1 at 755.8 W Kg-1 are obtained.


Assuntos
Carbono , Eletrólitos , Capacitância Elétrica , Eletrodos , Porosidade
2.
Waste Manag ; 105: 492-500, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-32143145

RESUMO

Sequential potassium hydroxide (KOH)-phosphoric acid (H3PO4) activation was applied to biomass waste to fabricate activated carbon microspheres (mCMs) with a controllable porous structure. Carbon microspheres (CMs) were first synthesized from xylose using a bottom-up approach of hydrothermal carbonization. Sequential KOH and H3PO4 activation was applied to the CMs in a KOH-carbon solid reaction. This created pores, which were further enlarged by adsorption of H3PO4. The KOH:carbon (C) and H3PO4:C molar ratios, and the H3PO4 heating rate and activation time, were varied to investigate the effect on average pore size and pore distribution. A uniform porous structure was formed without destruction of the spherical shape, and an almost 700-fold increase in surface area was obtained over the non-activated CMs. Following activation with H3PO4, phosphorous groups were found to be present at the surface of the carbon microspheres. The mCM was tested as a supercapacitor electrode and was shown to have a maximum specific capacitance of up to 277F g-1. A Ragone plot showed the maximum power density to be 173.88 W Kg-1. This increased specific capacitance was attributed to the increase in surface area and the presence of phosphorous-containing acid sites on the material surface.


Assuntos
Xilose , Biomassa , Capacitância Elétrica , Microesferas , Porosidade
3.
Chemosphere ; 242: 125259, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896176

RESUMO

Activated carbon (AC), prepared from dried loofah sponge, was supported on nickel foam to fabricate AC/Ni electrodes. The characteristics of ammonium electrosorption on AC/Ni electrodes was studied. Results showed that AC prepared in one-step activation (without pre-pyrolysis), i.e., OAC, had relatively low crystallinity, high mesoporosity, and high specific capacitance compared to those made in two-step carbonation followed by activation. Adsorption and desorption density of NH4+ were measured at constant potential of -1.0 V (vs. Hg/HgO) and +0.1 V (vs. Hg/HgO), respectively. Non-faradaic charging contributed to the electrochemical storage and adsorption of ammonium ions on the AC surface with a maximal charge efficiency of 80%, at an applied potential of -1.0 V (vs. Hg/HgO). Multiple-layer adsorption isotherm better described the electrosorption of ammonium ion on OAC/Ni electrodes yielding a maximum adsorption capacity of 6 mg-N g-1, which was comparable with other similar systems. Overall, results clearly demonstrated the effect of synthesis strategy on the capacitive charging behaviors of AC/Ni electrodes and its relationship to NH4+ electrosorption.


Assuntos
Compostos de Amônio/análise , Carvão Vegetal/química , Luffa/química , Níquel/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Capacitância Elétrica , Eletrodos , Íons , Modelos Teóricos , Propriedades de Superfície
4.
Waste Manag ; 102: 330-339, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31711027

RESUMO

Single-step synthesis of porous carbon (PC) from biomass is a challenge via microwave heating, because biomass rarely absorbs the microwave energy. Herein, wheat-straw-derived char, as a good microwave absorber, was used to achieve rapidly single-step synthesis of PC from an agricultural waste (wheat straw). KOH was used to generate abundant micropores in the PCs. High heating rate caused by microwave heating combined with the pyrolysis gases resulted in the formation of meso-/macropores. A series of post-oxidation reactions between active sites in the PCs and oxygen in the air led to the doping of oxygen-containing chemical groups. Consequently, the obtained PC possessed a high specific surface area of 1905 m2 g-1, a balanced pore distribution with abundant micropores (0.62 cm3 g-1), considerable content of meso-/macropores (0.53 cm3 g-1), and an oxygen-enriched structure (oxygen content up to 21.6%). These characteristics not only contributed to the achievement of a high specific capacitance of 268.5 F g-1 at 0.5 A g-1 for the resultant supercapacitor, but also resulted in an excellent rate capability with a high capacitance retention of 81.2% at 10 A g-1 in a gel electrolyte (polyvinyl alcohol/LiCl). This supercapacitor can extract a high energy density of 21.5 W h kg-1 at 0.5 A g-1 and a high power density of 7.2 kW kg-1 at 10 A g-1.


Assuntos
Carbono , Eletrólitos , Biomassa , Capacitância Elétrica , Porosidade
5.
Environ Technol ; 41(1): 36-48, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30681935

RESUMO

The pore structure, high surface area and good conductivity are the key properties for the electrochemical double layer based supercapacitors. The activated carbons were produced from the waste tea, utilising microwave pretreatment with H3PO4 and activation at 450°C. Sodium thiosulfate pentahydrate (Na2S2O3·5H2O) was used as sulphur doping agent at 800°C to enhance conductivity of the activated carbons. Supercapacitor electrodes were prepared from both the activated carbon (WTAC) and sulphur doped activated carbon (WTAC-S) samples and the electrochemical performances were tested in the presence of 6 M KOH and 1 M H2SO4 as electrolytes. The activated carbon samples were characterised by Brunauer-Emmett-Teller (BET) surface area, Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy (SEM/EDS) and Fourier Transform Infrared Spectroscopy (FTIR) analysis techniques. The electrochemical performance analyses were performed by galvanostatic charge-discharge (GCD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. The specific capacitance values of the WTAC and WTAC-S samples under the 1 A g-1 current density were found to be 89.3, 144.7 F g-1 for KOH electrolyte and 73.8 and 101.9 F g-1 for H2SO4 electrolyte, respectively. The results show that the sulphur doping process enhances the electrochemical performance of activated carbon samples.


Assuntos
Carvão Vegetal , Enxofre , Capacitância Elétrica , Eletrodos , Chá
6.
J Colloid Interface Sci ; 558: 211-219, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31586740

RESUMO

Porous interconnected carbon nanosheets (PICNs) with high electrochemical performance were prepared by doping urea and a co-hydrothermal precursor derived from soybean stalk (SS) and nickel nitrate. The specific surface area and average pore diameter of the as-synthesized PICNs are 2226.29 m2 g-1 and 1.89 nm, and their N and O contents are 5.08% and 9.4%, respectively, which is beneficial for increasing pseudocapacitance. Furthermore, the doping of the metal Ni increases the graphitization degree of the PICNs and promotes the conversion of pyridine-N to graphitized-N. Therefore, the PICNs possess a high specific capacitance of 407 F g-1 at a current density of 0.5 A g-1, a high capacitance retention of 78.62% even at 20 A g-1, and an outstanding cycling stability (over 93% retention rate after 10,000 charge/discharge cycles). Moreover, an energy density of 36.11 W h kg-1 is achieved at a power density of 517.8 W kg-1 during a two-electrode system test, and a retention rate of 87.5% is obtained after 10,000 cycles. This co-hydrothermal treatment as well as nitrogen-doping approach for preparing porous interconnected carbon from SS not only represents an alternative strategy for carbon-based supercapacitor materials but also provides a new option for the utilization of waste SS.


Assuntos
Carbono/química , Nanoestruturas/química , Níquel/química , Nitrogênio/química , Oxigênio/química , Soja/química , Capacitância Elétrica , Técnicas Eletroquímicas
7.
Water Res ; 171: 115370, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31864131

RESUMO

This study investigated the fouling and scaling behaviors in a capacitive deionization (CDI) system in the presence of iron and natural organic matter (NOM). It was found that the salt adsorption capacity (SAC) significantly decreased when treating Fe-containing brackish water, with higher Fe concentrations leading to severer SAC reduction. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis demonstrated that Fe2O3 appeared to be the predominant foulant attached on the electrode surface, which was difficult to be removed via backwashing, indicating the irreversible property of the foulant. Further characterizations (e.g., N2 sorption-desorption isotherms, electrochemical impedance spectroscopy and cyclic voltammetry) revealed that the CDI electrodes suffered from obvious deterioration such as specific surface area loss, resistance increase and capacitance decline with the occurrence of Fe scaling. While the presence of NOM alleviated the Fe scaling through NOM-Fe complexing effects, NOM itself was found to have negative impacts on CDI desalination performance due to their strong interactions with the carbon electrodes.


Assuntos
Ferro , Purificação da Água , Adsorção , Capacitância Elétrica , Eletrodos
8.
Carbohydr Polym ; 227: 115346, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31590873

RESUMO

This study reports excellent supercapacitor performance of hierarchical composite porous carbon (HPC) materials successfully fabricated by one-step carbonization and activation process derived from polysaccharides carboxymethyl cellulose, bacterial cellulose, and citric acid. The resultant HPC displayed unique porous nanosheet morphology with high specific surface area (2490 m2 g-1) and rich oxygen content (7.3%). The developed structures with macropores, mesopore walls, micropores, and high oxygen content led to excellent electrochemical performance for electrode of electric double-layer capacitors (EDLCs). In a three-electrode system, the HPC electrode showed a high specific capacitance of 350 F g-1, good rate performance, and excellent cycling stability. The energy density of supercapacitor based on HPC was comparable to or higher than that of commercially supercapacitors. More importantly, two series-wound devices were easy to light light-emitting diode (LED, 3.0 V). These results suggest that the current material is a promising candidate for low-cost and eco-friendly energy storage devices.


Assuntos
Celulose/química , Ácido Cítrico/química , Capacitância Elétrica , Polissacarídeos Bacterianos/química , Carbono/química , Fontes de Energia Elétrica , Eletrodos , Porosidade
9.
Biosens Bioelectron ; 147: 111784, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31654823

RESUMO

This paper presents a microwave sensor designed as a capacitive matrix for label-free Escherichia coli detection. The mean value of capacitances' change in the capacitive matrix sensor is an indicator of the bacteria detection. The theoretical analysis was confirmed by the realization of an exemplary sensor chip manufactured using the United Monolithic Semiconductor (UMS) PH25 process on a 100 µm thick GaAs substrate and measurements of various concentrations of Escherichia coli in the frequency range 1-3 GHz. The matrix topology of the sensor together with biofunctionalization of the sensor surface with polyclonal anti-Escherichia coli antibody allow to obtain high detection sensitivity on various concentrations of Escherichia coli reaching 103 CFU/ml. The obtained results are promising for future biomedical applications, in terms of specific bacteria presence detection.


Assuntos
Técnicas Biossensoriais , Infecções por Escherichia coli/diagnóstico , Escherichia coli/isolamento & purificação , Arsenicais/química , Capacitância Elétrica , Escherichia coli/patogenicidade , Infecções por Escherichia coli/microbiologia , Gálio/química , Humanos , Micro-Ondas
10.
Molecules ; 24(24)2019 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-31861201

RESUMO

A facile strategy, engineered for low-cost mass production, to synthesize biomass-derived activated carbon/reduced graphene oxide composite electrodes (GBPCs) by one-pot carbonization of blotting papers containing graphene oxide (GO) and zinc chloride (ZnCl2) was proposed. Benefitting from the water absorption characteristic of blotting papers in which the voids between the celluloses can easily absorb the GO/ZnCl2 solution, the chemical activation and reduction of GO can synchronously achieve via one-step carbonization process. As a result, the GBPCs deliver a large specific surface area to accumulate charge. Simultaneously, it provides high conductivity for electron transfer. The symmetric supercapacitor assembled with the optimal GBPCs in 6 M KOH electrolyte exhibits an excellent specific capacitance of 204 F g-1 (0.2 A g-1), outstanding rate capability of 100 F g-1 (20 A g-1). Meanwhile, it still keeps 90% of the initial specific capacitance over 10,000 cycles. The readily available raw material, effective chemical activation, simple rGO additive, and resulting electrochemical properties hold out the promise of hope to achieve low-cost, green, and large-scale production of practical activated carbon composite materials for high-efficiency energy storage applications.


Assuntos
Carvão Vegetal/química , Capacitância Elétrica , Eletrodos , Grafite/química , Algoritmos , Biomassa , Eletroquímica , Porosidade , Temperatura
11.
Molecules ; 24(19)2019 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-31590393

RESUMO

Coal-based porous materials for supercapacitors were successfully prepared using Taixi anthracite (TXA) by multi-stage activation. The characterization and electrochemical tests of activated carbons (ACs) prepared in different stages demonstrated that the AC from the third-stage activation (ACIII) shows good porous structures and excellent electrochemical performances. ACIII exhibited a fine specific capacitance of 199 F g-1 at a current density of 1 A g-1 in the three-electrode system, with 6 mol L-1 KOH as the electrolyte. The specific capacitance of ACIII remained 190 F g-1 even despite increasing the current density to 5 A g-1, indicating a good rate of electrochemical performance. Moreover, its specific capacitance remained at 98.1% of the initial value after 5000 galvanostatic charge-discharge (GCD) cycle tests at a current density of 1 A g-1, suggesting that the ACIII has excellent cycle performance as electrode materials for supercapacitors. This study provides a promising approach for fabricating high performance electrode materials from high-rank coals, which could facilitate efficient and clean utilization of high-rank coals.


Assuntos
Carvão Vegetal/síntese química , Carvão Mineral/análise , Carvão Vegetal/química , Capacitância Elétrica , Eletroquímica/instrumentação , Eletrodos , Microscopia de Força Atômica , Tamanho da Partícula , Porosidade , Propriedades de Superfície
12.
Molecules ; 24(20)2019 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-31614788

RESUMO

We report the synthesis of nitrogen-doped hierarchical meso/microporous carbon using renewable biomass bamboo fungus as precursor via two-step pyrolysis processes. It is found that the developed porous carbon (NHPC-800) features honeycomb-like cellular framework with well-developed porosity, huge specific surface area (1708 m2 g-1), appropriate nitrogen-doping level (3.2 at.%) and high mesopore percentage (25.5%), which are responsible for its remarkable supercapacitive performances. Electrochemical tests suggest that the NHPC-800 electrode offers the largest specific capacitance of 228 F g-1, asplendid rate capability and stable electrochemical behaviors in a traditional three-electrode system. Additionally, asymmetric supercapacitor device is built based on this product as well. An individual as-assembled supercapacitor of NHPC-800//NHPC-800 delivers the maximum energy density of 4.3 Wh kg-1; retains the majority of capacitanceat large current densities; and shows terrific cycling durability with negligible capacitance drop after long-term charge/discharge for beyond 10,000 cycles even at a high current density of 10 A g-1. These excellent supercapacitive properties of NHPC-800 in both three- and two-electrode setups outperform those of lots of biomass-derived porous carbons and thus make it a perspective candidate for producing cost-effective and high-performance supercapacitors.


Assuntos
Biomassa , Carbono/química , Fungos/química , Análise Custo-Benefício , Capacitância Elétrica , Nitrogênio/química , Porosidade , Sasa/química , Sasa/microbiologia
13.
Nanoscale ; 11(39): 18375-18381, 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31573596

RESUMO

Octacalcium phosphate (OCP) is classified as a low-temperature phase of calcium phosphate (CaPs); it is a widely used ceramic material in biomedical applications. Interestingly, this study demonstrated the capacitive behavior of OCP as an electrode material in supercapacitors, alternatively named biosupercaps, for the first time in the literature. OCP powder was synthesized by solution precipitation at pH 5.5 at 60 °C in the presence of succinic acid. X-Ray diffraction (XRD) fully confirmed the OCP phase, with a crystallite size of around 40 nm, as calculated by the Scherrer equation. The FE-SEM micrographs of the OCP powder revealed plate-like morphology with a high surface area/thickness ratio. The surface widths of these layers ranged from about 2 to 100 microns, whereas the thickness of the layers was on the nanoscale (<100 nm). Raman spectroscopy was performed to confirm the microstructural formation of the OCP powder and electrodes according to the Raman spectra. Asymmetric and symmetric capacitors were prepared by various designs using OCP powder as a potential electrode material. The electrochemical performance of each biosupercap containing OCP was analyzed by a potentiostat in terms of current-voltage (CV) curves; each sample presented a typical pseudocapacitive behaviour. The electrochemical impedance spectra (EIS) of the OPC materials confirmed their significant capacitive performance, with up to 6 mA h g-1 specific capacity (SCp); this may be valuable for future medical electronics such as biocompatible energy storage and harvesting microdevices.


Assuntos
Fosfatos de Cálcio/química , Cerâmica/química , Capacitância Elétrica , Nanopartículas/química , Eletrodos
14.
Molecules ; 24(19)2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31569650

RESUMO

In this report, a facile solution casting technique was used to fabricate polymer blend electrolytes of chitosan (CS):poly (ethylene oxide) (PEO):NH4SCN with high electrochemical stability (2.43V). Fourier transform infrared (FTIR) spectroscopy was used to investigate the polymer electrolyte formation. For the electrochemical property analysis, cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS) techniques were carried out. Referring to the FTIR spectra, a complex formation between the added salt and CS:PEO was deduced by considering the decreasing and shifting of FTIR bands intensity in terms of functional groups. The CS:PEO:NH4SCN electrolyte was found to be electrochemically stable as the applied voltage linearly swept up to 2.43V. The cyclic voltammogram has presented a wide potential window without showing any sign of redox peaks on the electrode surface. The proved mechanisms of charge storage in these fabricated systems were found to be double layer charging. The EIS analysis showed the existence of bulk resistance, wherein the semicircle diameter decreased with increasing salt concentration. The calculated maximum DC conductivity value was observed to be 2.11 × 10-4 S/cm for CS:PEO incorporated with 40 wt% of NH4SCN salt. The charged species in CS:PEO:NH4SCN electrolytes were considered to be predominantly ionic in nature. This was verified from transference number analysis (TNM), in which ion and electron transference numbers were found to be tion = 0.954 and tel = 0.045, respectively. The results obtained for both ion transference number and DC conductivity implied the possibility of fabricating electrolytes for electrochemical double layer capacitor (EDLC) device application. The specific capacitance of the fabricated EDLC was obtained from the area under the curve of the CV plot.


Assuntos
Quitosana/química , Capacitância Elétrica , Eletroquímica , Eletrólitos/química , Polímeros/química , Prótons , Impedância Elétrica , Espectroscopia de Infravermelho com Transformada de Fourier
16.
Sensors (Basel) ; 19(18)2019 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-31505727

RESUMO

With the development of wearable devices, strain sensors have attracted large interest for the detection of human motion, movement, and breathing. Various strain sensors consisting of stretchable conductive materials have been investigated based on resistance and capacitance differences according to the strain. However, this method requires multiple electrodes for multipoint detection. We propose a strain sensor capable of multipoint detection with a single electrode, based on the ultrasound pulse-echo method. It consists of several transmitters of carbon nanotubes (CNTs) and a single polyvinylidene fluoride receiver. The strain sensor was fabricated using CNTs embedded in stretchable polydimethylsiloxane. The received data are characterized by the different times of transmission from the CNTs of each point depending on the strain, i.e., the sensor can detect the positions of the CNTs. This study demonstrates the application of the multipoint strain sensor with a single electrode for measurements up to a strain of 30% (interval of 1%). We considered the optical and acoustic energy losses in the sensor design. In addition, to evaluate the utility of the sensor, finger bending with three-point CNTs and flexible phantom bending with six-point CNTs for the identification of an S-curve having mixed expansion and compression components were carried out.


Assuntos
Técnicas Biossensoriais , Entorses e Distensões/diagnóstico , Dispositivos Eletrônicos Vestíveis , Capacitância Elétrica , Humanos , Movimento (Física) , Movimento/fisiologia , Respiração , Entorses e Distensões/fisiopatologia
17.
Biosens Bioelectron ; 143: 111623, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31472413

RESUMO

For the treatment of bacteremia, early diagnosis and rapid antibiotic susceptibility tests (ASTs) are necessary because survival chances decrease significantly if the proper antibiotic administration is delayed. However, conventional methods require several days from blood collection to AST as it requires three overnight cultures, including blood culture, subculture, and AST culture. Herein, we report a more rapid method of sensing bacterial growth and AST in blood based on a vertical capacitance sensor functionalized with aptamers. Owing to their vertical structure, the influence of blood cells sunk by gravity on capacitance measurements were minimized. Thus, bacterial growth in blood at 100-103 CFU/mL was monitored in real-time by measuring changes in capacitance at f = 10 kHz. Moreover, real-time capacitance measurements at f = 0.5 kHz provided information on biofilm formation induced during blood cultures. Bacterial growth and biofilm formation are inhibited above the minimal inhibitory concentration of antibiotics; therefore, we also demonstrated that vertical capacitance aptasensors could be applied to rapid AST from positive blood cultures without a need for the subculture process.


Assuntos
Antibacterianos/sangue , Bacteriemia/sangue , Técnicas Bacteriológicas , Técnicas Biossensoriais , Aptâmeros de Nucleotídeos/química , Capacitância Elétrica , Humanos , Testes de Sensibilidade Microbiana , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
18.
Colloids Surf B Biointerfaces ; 181: 1004-1011, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31382327

RESUMO

We report the effect of ionic liquids on chemically synthesized hierarchical-like copper oxide (CuO) thin films for supercapacitor applications. Concisely, the CuO thin films were deposited via chemical bath deposition (CBD) using 2-dimethylimidazolium chloride [HPDMIM(C1)], 1-(2',3'-dihydroxypropyl)-3-methylimidazolium chloride [DHPMIM(C1)], and N-(3-methyl-2-oxopropyl)pyridine chloride [MOCPP(C1)] ionic liquid solvents. The effects of the ionic liquid solvents on the morphological evolution of the as-prepared films were analyzed, and electrochemical properties were investigated. The highest specific capacitance was achieved for the electrode with a nanosheet-like structure produced by functionalization with the HPDMIM(C1) ionic liquid. The maximum specific capacitance achieved for the HPDMIM(C1):CuO hybrid electrode was 464 F g-1 at 5 mV s-1 in a 1 M Na2SO4 electrolyte. Thus, our findings, in addition to the stability of the HPDMIM(C1):CuO, indicate that it is a candidate for energy-storage applications.


Assuntos
Cobre/química , Capacitância Elétrica , Líquidos Iônicos/química , Nanoestruturas/química , Técnicas Eletroquímicas , Eletrodos , Tamanho da Partícula , Solventes/química , Propriedades de Superfície
19.
Molecules ; 24(16)2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31416287

RESUMO

Electrochemical anodized titanium dioxide (TiO2) nanotubes are of immense significance as electrochemical energy storage devices owing to their fast electron transfer by reducing the diffusion path and paving way to fabricating binder-free and carbon-free electrodes. Besides these advantages, when nitrogen is doped into its lattice, doubles its electrochemical activity due to enhanced charge transfer induced by oxygen vacancy. Herein, we synthesized nitrogen-doped TiO2 (N-TiO2) and studied its electrochemical performances in supercapacitor and as anode for a lithium-ion battery (LIB). Nitrogen doping into TiO2 was confirmed by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) techniques. The electrochemical performance of N-TiO2 nanotubes was outstanding with a specific capacitance of 835 µF cm-2 at 100 mV s-1 scan rate as a supercapacitor electrode, and it delivered an areal discharge capacity of 975 µA h cm-2 as an anode material for LIB which is far superior to bare TiO2 nanotubes (505 µF cm-2 and 86 µA h cm-2, respectively). This tailor-made nitrogen-doped nanostructured electrode offers great promise as next-generation energy storage electrode material.


Assuntos
Capacitância Elétrica , Fontes de Energia Elétrica , Eletrodos , Íons/química , Lítio/química , Nanotubos , Nitrogênio/química , Titânio/química , Técnicas Eletroquímicas , Eletroquímica , Nanotubos/ultraestrutura , Análise Espectral
20.
ACS Appl Mater Interfaces ; 11(36): 33347-33355, 2019 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-31424908

RESUMO

Wearable sensors for smart textile applications have garnered tremendous interest in recent years and can have enormous potential for human machine interfaces and digital health monitoring. Here, we report a soft capacitive microfiber sensor that can be woven seamlessly into textiles for strain measurement. Comprising a dual-lumen elastomeric microtube and liquid metallic alloy, the microfiber sensor enables continual strain perception even after being completely severed. In addition, our microfiber sensor is highly stretchable and flexible and exhibits tunable sensitivity, excellent linearity, a fast response, and negligible hysteresis. More importantly, the microfiber sensor is minimally affected by train rate and compression during strain sensing. Even under drastic environmental changes, the microfiber sensor presents good electrical stability. By integrating the microfiber sensor imperceptibly with textiles, we devise smart textile wearables to interpret hand gestures, detect limb motion, and monitor respiration rate. We believe that this sensor presents enormous potential in unobtrusive continuous health monitoring.


Assuntos
Capacitância Elétrica , Têxteis , Dispositivos Eletrônicos Vestíveis
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