The electrochemical deposition of composite poly(3,4-ethylenedioxythiophene) (PEDOT):polypyrrole (PPy)/activated carbon (AC) film is fabricated in a solution composed of 10 mM concentrations of each ...monomer (3, 4-Ethylenedioxythiophene (EDOT) and Pyrrole (Py) in (1:1)) and 0.1 M lithium perchlorate (LiClO
4
) aqueous solution as a supporting electrolyte at a potential 1.1 V which is found by obtaining Linear Sweep Voltammetry intercept point of the two monomers. AC particles (50 gL
−1
) are dispersed in this solution. The prepared composite films are analyzed by the scanning electron microscope (SEM) for surface morphology and polymer functional groups are analyzed by the Fourier transform infrared (FTIR) analysis. The SEM results have shown that PEDOT:PPy/AC composite film is porous structure which proved the deposition of AC and also, BET analysis was performed for surface area and pore size measurement. The FTIR spectra confirmed the functional group of conductive polymers (PEDOT and PPy) present in the composite film deposited on ITO (1 cm
2
) glass. The electrochemical measurements of the prepared samples are evaluated by using galvanostatic charge/discharge (GCD) and cyclic voltammetry in 2 M KCl aqueous solution in three electrodes set up. Also, electrochemical impedance spectroscopy is analyzed by using 5 mM aqueous solution of K
3
Fe (CN)
6
including 0.1 M KCl (supporting electrolyte) aqueous solution within three-electrode cell system. The value of specific capacitance of synthesized composite is evaluated from GCD and its value found to be 622 Fg
−1
by applying current density value of 1 Acm
−2
. Moreover, energy density value along with power density value of the composite PEDOT: PPy/AC are calculated and found to be 47 Whkg
−1
and 2223 Wkg
−1
, respectively. It has also been analyzed that this composite retained 87.5% cyclic stability. So, all of the above mentioned analysis reflect that PEDOT:PPy/AC composite is a potential electrode material employed in supercapacitors. It is worth mentioning that PEDOT:PPy/AC composite electrode has improved the storage capacity of the prepared device.
At present it is indispensable to develop and implement new/state-of-the-art carbon nanomaterials as electrodes in electrochemical capacitors, since conventional activated carbon based supercapacitor ...cells cannot fulfil the growing demand of high energy and power densities of electronic devices of the present era, as a result of the rapid developments in this field. Functionalized carbon nanomaterials symbolize the type of materials with huge potential for their use in energy related applications in general and as an electrode active material for electrochemical capacitors in particular. Nitrogen doping of carbons has shown promising results in the field of energy storage in electrochemical capacitors, gaining attention of researchers to evaluate the performance of new heteroatoms functionalised materials such as sulphur, phosphorus and boron lately. Literature is widely available on nitrogen doped materials research for energy storage applications; however, there has been a limited number of review works on other functional materials beyond nitrogen. This review article thus aims to provide important insights and an up-to-date analysis of the most recent developments, the directions of future research, and the techniques used for the synthesis of these functional materials. A critical review of the electrochemical performance including specific capacitance and energy/power densities is made, when these single doped or co-doped active materials are used as electrodes in electrochemical capacitors.
•Recent progress in synthesis of functionalized nanostructured carbon materials.•Heteroatoms doped carbon nanomaterials improves specific capacitance.•Heteroatoms doping results in improving energy density while maintaining the excellent power density.
Building flexible asymmetric supercapacitors (ASCs) with high-capacitance, high energy density and a super long life will contribute to the development of new energy storage devices in the future. ...Although ASCs possess a higher energy density than symmetric supercapacitors (SCs), however, lifespan is effectively degraded during the long-term cycling process. Herein, we demonstrate a high-performance all-solid-state flexible ASC based on battery-type bimetallic oxide (ZnCo2O4) nano-polyhedra supported on carbon fibre textiles (ZCO@CFT) as the cathode and capacitive-type layer structured Ti3C2Tx-MXene as the anode materials. Before assembling the ASC, both electrodes were systematically investigated in aqueous electrolyte and their performance optimized. The ZCO@CFT cathode exhibits high pseudocapacitive charge storage (∼63.22%) with a specific capacitance of 2643.66 F g−1 at 2 A g−1 and Ti3C2Tx-MXene supported on carbon fibre textile (MXene@CFT) exhibits a high specific capacitance of 474.23 F g−1 at 1.5 A g−1 with remarkable cycling stabilities >95%. Furthermore, the ASCs were fabricated using ZCO@CFT as the cathode and MXene@CFT as the anode, (denoted as ZCO‖MXene-ASC) to check the feasibility of the proposed design. The ZCO‖MXene-ASC shows excellent energy storage properties by achieving a high capacitance of 281.25 F g−1 at 0.5 A g−1, a highly competitive energy density of 99.94 W h kg−1 at an admirable power density of 800 W kg−1 with a good life-time >94% over 5000 cycles and flexibility. According to the best of our knowledge, the achieved energy density of ZCO‖MXene-ASC is very competitive, and the highest among all binary metal oxides, carbonaceous materials, and MXene-based SCs and ASCs to date. Our concept of employing 3D bimetallic-oxides and 2D Ti3C2Tx-MXene could open up a new direction in the development of high-performance flexible energy storage devices.
Perovskite based materials have become an attractive anode for fuel cell due to the significant conductivity, carbon resistivity and sulphur tolerance. Doping of Ce on B-site of the La
0.4
Sr
0.6
Ce
...x
Ti
1−
x
O
(
x
= 0.02, 0.04, 0.06, 0.08) with different dopant concentrations is prepared using sol-gel technique. The synthesized material is analyzed by numerous techniques. X-ray diffraction confirmed the cubic perovskite structure (JCPDS 01-079- 0183) with average crystallite size of 35 nm. UV–Vis spectroscopy revealed the red shift in band gap (2.76 eV) compared to LaSrTiO
. Scanning electron microscopy shows the homogeneity and porosity in the prepared material. The observed particle size is in the range of 50–60 nm. The presence of the lanthanum, strontium, cerium, titanium and oxygen ions is confirmed by EDX. The Raman spectra and XRD, confirmed that cerium ions have been diffused in the lattice structure of LSTO
. The La
0.4
Sr
0.6
Ce
0.08
Ti
0.92
O
anode showed the highest conductivity of 2.67 S cm
–1
with lower activation energy of 0.20 eV as compared to other three samples. The power density of 58 mW cm
–2
at 600°C with 0.9 V OCV is achieved for the composition La
0.4
Sr
0.6
Ce
0.08
Ti
0.92
O
using sub-bituminous fuel. The observed results show that prepared material is potential ceramic anode for direct carbon fuel cell.
Environmental contamination has been a major source of concern for the world in recent decades. Pollutants in the environment are harmful entities that can cause severe diseases and pose a serious ...threat to the ecosystem. As a result, it becomes compulsion for modern researchers to develop such remarkable sensors that are capable of detecting contaminants in aqueous environment. In order to develop a sensitive and selective sensor for the targeted determination of Bisphenol-A (BPA), an endocrine-disrupting compound, a very efficient Cd/rGO composite was synthesized through a green microwave-assisted route. The prepared Cd/rGO composite was characterized by different analytical tools, e.g. XRD, EDX, FTIR and SEM, to study phase structure, elemental composition, functionalities, and sheets morphology, respectively. To evaluate the sensing properties of fabricated sensing material glassy carbon electrode was modified and resulting Cd/rGO/GCE was initially electrochemically characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (ESI). At optimized conditions such as scan rate of 70 mV/s, PBS electrolyte of pH 7, potential window in the range of 0.0–0.9 V vs Ag/AgCl; the fabricated Cd/rGO/GCE-based sensor showed the outstanding response for BPA. Under the linear concentration range from 5 to 110 µM, the LOD and LOQ were calculated as 0.041 and 0.13 µM, respectively. Moreover, the analytical applicability of the proposed sensor was tested in different water samples, which revealed acceptable recovery values from 91.1 to 101.1%. The comprehensive experimental studies witness the reliability of the proposed method and confirm that it could be a promising electrochemical sensor to be used at the commercial level.
Graphical abstract
Electrochemical energy storage and conversion systems such as electrochemical capacitors, batteries and fuel cells are considered as the most important technologies proposing environmentally friendly ...and sustainable solutions to address rapidly growing global energy demands and environmental concerns. Their commercial applications individually or in combination of two or more devices are based on their distinguishing properties e.g., energy/power densities, cyclability and efficiencies. In this review article, we have discussed some of the major electrochemical energy storage and conversion systems and encapsulated their technological advancement in recent years. Fundamental working principles and material compositions of various components such as electrodes and electrolytes have also been discussed. Furthermore, future challenges and perspectives for the applications of these technologies are discussed.
Gadolinium doped tin oxide–iron oxide nanoparticles (Gd/Fe
1.727
Sn
0.205
O
3
) were synthesized via sol–gel method followed by hydrothermal method. Ethylene glycol played the role of directing agent ...to control surface morphology. Physical and optical properties of Gd/Fe
1.727
Sn
0.205
O
3
nanoparticles were studied as a function of calcination temperature. Characterization techniques like thermogravimetric analysis (TGA), fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), particle size analyzer (PSA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Visible spectroscopy (UV–VIS), and four-point probe technique have been used to study the thermal degradation, kinetics, thermodynamic properties, structural analysis, surface morphology, optical and electrical properties of nanoparticles. Prominent peaks in FTIR spectra at 563, 418, and 542 cm
−1
were observed for Fe–O, Sn–O, and Gd–O, respectively. The uncalcined nanoparticles follow first order kinetics and Freeman–Carrol method was applied for calculating the activation energy. It was observed that nanoparticles calcined at 700 °C have 8.9 nm particle size calculated with particle size analyzer, which is smallest among all and having band gap energy of 2.3 eV. SEM micrographs show hexagonal geometry. The dependence of electrical resistance on temperature shows that these nanoparticles possess semiconducting behavior. These nanoparticles can be used as cathode material for solid oxides fuel cells (SOFCs) application. The nanoparticles calcined at 700 °C showed highest power density of 83.27 W cm
−2
at 650 °C with open current voltage of 0.793 V.
Highlights
Novel high surface area of Gd/Fe
1.727
Sn
0.205
O
3
nanoparticles were synthesized using sol–gel and hydrothermal methods.
The smallest band gap and particle size was observed for the sample calcined at 700 °C.
Four probe dc conductivity value recoded was 0.709 mS/cm for sample calcined at 700 °C.
Solid oxides fuel cell (SOFC) demonstrates that Gd/Fe
1.727
Sn
0.205
O
3
as cathode performed better when calcined at 700 °C with high power density of 83.27 W cm
−2
.
Highlights
Ceria-based heterostructure composite for novel semiconductor-ionic fuel cells.
Superionic conduction at interfaces is associated with the crossover of band structure.
Band ...alignment/bending resultant built-in field plays a significant role in superionic conduction.
Ceria-based heterostructure composite (CHC) has become a new stream to develop advanced low-temperature (300–600 °C) solid oxide fuel cells (LTSOFCs) with excellent power outputs at 1000 mW cm
−2
level. The state-of-the-art ceria–carbonate or ceria–semiconductor heterostructure composites have made the CHC systems significantly contribute to both fundamental and applied science researches of LTSOFCs; however, a deep scientific understanding to achieve excellent fuel cell performance and high superionic conduction is still missing, which may hinder its wide application and commercialization. This review aims to establish a new fundamental strategy for superionic conduction of the CHC materials and relevant LTSOFCs. This involves energy band and built-in-field assisting superionic conduction, highlighting coupling effect among the ionic transfer, band structure and alignment impact. Furthermore, theories of ceria–carbonate, e.g., space charge and multi-ion conduction, as well as new scientific understanding are discussed and presented for functional CHC materials.
The direct carbon fuel cell (DCFC) is an efficient device that converts the carbon fuel directly into electricity with 100% theoretical efficiency contrary to practical efficiency around 60%. In this ...paper four perovskite anode materials La0.4Sr0.6M0.09Ti0.91O3-δ (M = Ni, Fe, Co, Zn) have been prepared using sol-gel technique to measure the performance of the device using solid fuel. These materials have shown reasonable stability and conductivity at 700 °C. Further structural analysis of as-prepared anode material using XRD technique reveals a single cubic perovskite structure with average crystallite size roughly 47 nm. Walnut and almond shells biochar have also been examined as a fuel in DCFC at the temperature range 400–700 °C. In addition, Elemental analysis of walnut and almond shells has shown high carbon content and low nitrogen and sulfur contents in the obtained biochar. Subsequently, the superior stability of as-prepared anode materials is evident by thermogravimetric analysis in pure N2 gas atmosphere. Conversely, the LSFT anode has shown the highest electronic conductivity of 7.53Scm−1 at 700 °C. The obtained power density for LSFTO3-δ composite anode mixed in sub-bituminous coal, walnut and almond shells biochar is of 68, 55, 48 mWcm−2 respectively. A significant improvement in performance of DCFC (78 mWcm−2) was achieved.
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•Potential titanate based anodes La0.4Sr0.6M0.09Ti0.91O3-δ for DCFC.•LSFTO3-δ anode exhibits the best electrical conductivity of 7.53Scm−1 at 700 °C.•The best performance of 78 mWcm−2 achieved with Sub-bituminous fuel.
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