Transition metal oxides are nowadays one of the most important materials in the manufacture of capacitive electrodes. The most important problems with these materials for applied energy storage ...devices are low specific energy and poor electrical conductivity. In this research nickel ferrite nanoparticles (NiFe2O4) and also hybrid of NiFe2O4/rGO are synthesized by hydrothermal method and characterized by XRD, Raman, and XPS analysis. The amount of porosity and specific surface area is studied by BET analysis as and surface morphology is studied by SEM and TEM. To investigate the effect of adding rGO to NiFe2O4 nanoparticles, from a hybrid electrode superconducting electrochemical tests are performed, including CV, EIS, and charge-discharge. This electrode with a capacitance of 584.63 F/g and capacitance retention of 91% after 2000 consecutive cycles can be a tempting option for supercapacitor applications.
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•Synthesis of NiFe2O4/rGO by the hydrothermal method.•Electrochemical reactions occur during a diffusion-controlled process.•NiFe2O4/rGO shows a great capacitance retention of 91% after 2000 cycles.
A new sulfonated aromatic diamine monomer containing nitrogen heterocycles was synthesized and employed to prepare a novel sulfonated polyimide (SPI). To develop proton exchange membranes, new ...nanocomposite blend membranes consist of the prepared SPI and polybenzimidazole (PBI) were fabricated with incorporation of SrCe0.9Yb0.1O3-δ (SCYb) doped-perovskite nanoparticles with a solution-casting method. The goal of this work is to study the effect of SPI and SCYb doped-perovskite nanoparticles on the important parameters of the PBI membrane specially proton conductivity and fuel cell performance. The proton conductivity and phosphoric acid doping level of the PBI-SPI-SCYb nanocomposite blend membranes improved due to an interaction of –SO3H group and thiazole rings of SPI and N–H groups of PBI in the oxygen vacancies of SCYb doped-perovskite nanoparticles. Substitution of Ce4+ by Yb3+ in the SCYb doped-perovskite nanoparticles produce oxygen vacancies and decrease the columbic repulsion between protons and positive ions. Furthermore at highest phosphoric acid doping level of 14 mol phosphoric acid per monomer unit, the nanocomposite blend membranes displayed proton conductivity of 131 mS/cm at 180 °C and 8% relative humidity. The increase in power density from 0.31 W/cm2 in PBI-SPI blend membranes (SPI/PBI: 25 wt%) to 0.59 W/cm2 in PBI-SPI-SCYb nanocomposite blend membranes (SPI/PBI: 25 wt% and 7 wt% of SCYb) was achieved at 0.5 V, 8% RH and 180 °C, which demonstrates that these developed nanocomposite blend membranes have a high potential to be regarded as the most promising candidates for high-temperature fuel cell with improved proton conductivity.
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•SrCe0.9Yb0.1O3-δ (SCYb) doped-perovskite nanoparticles acted as one of the fastest available proton conductors.•Substitution of Ce4+ by Yb3+ in the SCYb nanoparticles produce oxygen vacancies.•The oxygen vacancies in the SCYb nanoparticles act as hydrogen traps.•Interaction of sulfonated polyimide (SPI) and PBI in the oxygen vacancies increase the proton conductivity.•The SPI/PBI/SCYb nanocomposite blend membranes show a power density of 0.59 W/cm2.
Transition metal oxides can be performant electrode materials for supercapacitors and alcohol oxidation if their conductivity and capacity are improved. Herein, an advanced nanocomposite material ...made of NiO‐Co3O4 on reduced graphene oxide (rGO) is synthesized by a one‐step hydrothermal method for supercapacitors and methanol/ethanol oxidation. It is demonstrated that the nanocomposite is a promising material for energy storage as NiO‐Co3O4‐rGO supercapacitor electrodes achieve a specific capacity of 149 mAh g−1 (894 F g−1) at a current density of 0.5 A g−1, the discharge time of 689 s, and excellent stability of 95% after 6000 cycles. Moreover, NiO‐Co3O4‐rGO shows a current density of 15 and 10 mA cm−2 in methanol and ethanol oxidation reactions, respectively, along with excellent stability.
NiO‐Co3O4 and NiO‐Co3O4/rGO multicomponent nanocomposites are used for supercapacitors and alcohol oxidation. The synergistic effects between the two metal oxides and the hybridization with reduced graphene oxide lead to supercapacitors with high specific capacity and long discharge time as well as methanol and ethanol oxidation processes with high current density and reduced overvoltage.
Abstract
In this study, new nanocomposite membranes from sulfonated poly (ether ether ketone) (SPEEK) and proton-conducting Fe
2
TiO
5
nanoparticles are prepared by the solution casting method. ...Sulfonated core–shell Fe
2
TiO
5
nanoparticles are synthesized by redox polymerization. Therefore, 4-Vinyl benzene sulfonate (VBS) and 2-acrylamide-2-methyl-1-propane sulfonic acid (AMPS) are grafted on the surface of nanoparticles through radical polymerization. The different amounts of hybrid nanoparticles (PAMPS@Fe
2
TiO
5
and PVBS@Fe
2
TiO
5
) are incorporated into the SPEEK matrix. The results show higher proton conductivity for all prepared nanocomposites than that of the SPEEK membrane. Embedding the sulfonated Fe
2
TiO
5
nanoparticles into the SPEEK membrane improves proton conductivity by creating the new proton conducting sites. Besides, the nanocomposite membranes showed improved mechanical and dimensional stability in comparison with that of the SPEEK membrane. Also, the membranes including 2 wt% of PAMPS@Fe
2
TiO
5
and PVBS@Fe
2
TiO
5
nanoparticles indicate the maximum power density of 247 mW cm
−2
and 226 mW cm
−2
at 80 °C, respectively, which is higher than that of for the pristine membrane. Our prepared membranes have the potential for application in polymer electrolyte fuel cells.
Nanocomposite membranes based on the poly(vinyl alcohol) (PVA)/poly(sulfonic acid)-grafted silica nanoparticles (PSA-g-SN) were prepared via solvent casting of PVA cross linked by glutardialdehyde in ...the presence of various amounts (0–20 wt%) of silica nanoparticles (SN), poly(styrene sulfonic acid)- (PSSA-g-SN) and poly (2-acrylamido-2-methyl-1-propane sulfonic acid)-grafted silica nanoparticles (PAMPS-g-SN) as hydrophilic inorganic modifiers. PSA-g-SN nanoparticles were synthesized by surface-initiated redox grafting of SSA and AMPS monomers from the surface of the aminopropylated silica nanoparticles. Membranes were then characterized by FTIR, impedance spectroscopy, thermogravimetric analysis (TGA), water uptake, tensile strength test and SEM. The best proton conductivity was observed for membranes containing 5 wt% of nanoparticles. Among three nanoparticles used, the highest proton conductivity (10.4 mS/cm) was observed for PVA membrane prepared in the presence of 5 wt% PAMPS-g-SN nanoparticles. Results showed that grafting of sulfonated monomer onto the silica nanoparticles enhances various properties, for example proton conductivity, of the polymer electrolyte membranes (PEMs).
► New proton conducting nanocomposite membrane was prepared. ► Grafting of poly (sulfonic acid) onto the silica enhances proton conductivity. ► The membranes with 5 wt% of nanoparticles showed the best conductivity.
The potential of metal oxides in electrochemical energy storage encouraged our research team to synthesize molybdenum oxide/tungsten oxide nanocomposites (MoO3/WO3) and their hybrid with reduced ...graphene oxide (rGO), in the form of MoO3/WO3/rGO as a substrate with relatively good electrical conductivity and suitable electrochemical active surface. In this context, we presented the electrochemical behavior of these nanocomposites as an electrode for supercapacitors and as a catalyst in the oxidation process of methanol/ethanol. Our engineered samples were characterized by X-ray diffraction pattern and scanning electron microscopy. As a result, MoO3/WO3 and MoO3/WO3/rGO indicated specific capacitances of 452 and 583 F/g and stability of 88.9% and 92.6% after 2000 consecutive GCD cycles, respectively. Also, MoO3/WO3 and MoO3/WO3/rGO nanocatalysts showed oxidation current densities of 117 and 170 mA/cm2 at scan rate of 50 mV/s, and stability of 71 and 89%, respectively in chronoamperometry analysis, in the MOR process. Interestingly, in the ethanol oxidation process, corresponding oxidation current densities of 42 and 106 mA/cm2 and stability values of 70 and 82% were achieved. MoO3/WO3 and MoO3/WO3/rGO can be attractive options paving the way for prospective alcohol-based fuel cells.
The present study aims to assess the proton conductivities of the most investigated proton exchange membranes (PEMs) used in PEM fuel cells (PEMFCs). Specifically, PEMs are analyzed for their use in ...anhydrous fuel cells and proton conductivity upper bounds were provided for them. Considering the direct relationship between proton conductivity and temperature, an upper bound is presented. Based on the obtained upper bounds, suitable membranes for high-temperature performance are determined, and the average range of proton conductivity for each polymer group is discussed. By comparing the available proton conductivity data with upper bound, it was demonstrated that some of poly (ionic liquid)s have provided the highest proton conductivities, however aromatic polymers such as polybenzimidazole (PBI) are found more suitable choices for application at anhydrous conditions and high temperatures. The proton conductivity upper bound for anhydrous PEMs demonstrates the availability of promising polymer options for the deployment of anhydrous fuel cells.
•The proton conductivity of the most investigated PEMs used in anhydrous fuel cells was investigated.•The proton conductivity upper bound for anhydrous PEMs was presented.•Nafion, polybenzimidazole and polyetheretherketone are the most investigated polymers for anhydrous fuel cells.
A carbon paste electrode modified with ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) and MoO
3
/WO
3
nanocomposite (MoO
3
/WO
3
/ILCPE) as an electrochemical sensor was developed for ...co-detection of tartrazine and carmoisine. Differential pulse voltammetry (DPV) method was applied to evaluate the electrochemical responses of tartrazine and carmoisine, the results of which confirmed a significant improvement of electrochemical behaviors on the modified electrode surface. High peak separation of oxidation (800 mV) made possible the co-detection of tartrazine and carmoisine. The DPV data in 0.1 M phosphate buffer solution at a pH value of 7.0 made it possible to develop a method for determining carmoisine in the dynamic range of 0.5–100 µM with the limit of detection of 0.15 µM. Also, the fabricated sensor showed good stability and selectivity. Our modified sensor could successfully detect these compounds in the real fruit specimens.
Today, finding low-cost electro-catalysts for methanol and ethanol oxidation with high performance and stability is one of the new research topics. A nanocatalyst based on metal oxides in the form of ...MnMoO4 was synthesized by a hydrothermal method for methanol (MOR) and ethanol (EOR) oxidation reactions. Adding reduced graphene oxide (rGO) to the catalyst structure improved the electrocatalytic activity of MnMoO4 for the oxidation processes. The crystal structure and morphology of the MnMoO4 and MnMoO4-rGO nanocatalysts were investigated by physical analyses such as scanning electron microscopy and X-ray diffraction. Their abilities for MOR and EOR processes in an alkaline medium were evaluated by performing electrochemical tests such as cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. MnMoO4-rGO showed oxidation current densities of 60.59 and 25.39 mA/cm2 and peak potentials of 0.62 and 0.67 V in MOR and EOR processes (at a scan rate of 40 mV/s), respectively. Moreover, stabilities of 91.7% in MOR and 88.6% in EOR processes were obtained from the chronoamperometry analysis within 6 h. All these features make MnMoO4-rGO a promising electrochemical catalyst for the oxidation of alcohols.
This research constructed and utilized a screen-printed electrode (SPE) modified with V
2
O
5
nanoparticles (NPs) (V
2
O
5
/SPE) employed in order to sensitively and selectively quantify ...ciprofloxacin with exceptional accuracy in the phosphate buffer solution (PBS) with the use of differential pulse voltammetry (DPV). Moreover, electrochemical properties of this new V
2
O
5
/SPE sensor have been examined using diverse characterization procedures. Very good V
2
O
5
/SPE electrochemical features offered sensitive ciprofloxacin voltammetric determination with the reduced limit of detection (LOD = 0.01 µM) toward electrocatalytic oxidation of ciprofloxacin in comparison with the bare SPE. Finally, this new disposable sensor exhibited higher sensitivity and thus has been efficiently utilized to determine ciprofloxacin in the real samples.
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