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1 – 10 of 36The purpose of this paper is to introduce bio-inspired FeN4-S-C black nano-electrocatalyst for the oxygen reduction reaction (ORR) in an alkaline medium. The FeN4-S-C derived…
Abstract
Purpose
The purpose of this paper is to introduce bio-inspired FeN4-S-C black nano-electrocatalyst for the oxygen reduction reaction (ORR) in an alkaline medium. The FeN4-S-C derived without pyrolysis of precursors in high temperature is recognized as a new electrocatalyst for the ORR in an alkaline electrolyte. For the proper design of bio-inspired nano-electrocatalyst for the ORR performance, chlorinated iron (II) phthalocyanine nanoparticles were used as templates for achieving the active sites in aqueous KOH by rotating disk electrode methods. The most active FeN4-S-C catalyst exhibited a remarkable ORR activity in the alkaline medium. The objectives of this paper are to investigate the possibility of nanoscale particles size (˜5nm) of electrocatalyst, to achieve four-electron transfer mechanism and to exhibit much superior catalytic stability in measurements. This paper will shed light on bio-inspired FeN4-S-C materials for the ORR catalysis in alkaline fuel cells.
Design/methodology/approach
The paper presents a new bio-inspired nano-electrocatalyst for the ORR, which has activity nearby platinum/carbon electrocatalyst. Chlorinated iron phthalocyanine nanoparticles have been used as FeN4 template, which is the key point for the ORR. Bio-inspired nano-electrocatalyst has been fabricated using chlorinated iron phthalocyanine, sodium sulphide and carbon black.
Findings
The particles’ size was 5 nm and electron transfer number was 4.
Research limitations/implications
The catalyst that is used in this method should be weighed carefully. In addition, the solvent should be a saturated solution of NaCl in water.
Practical implications
The method provides a simple and practical solution to improving the synthesis of iron-based catalyst for ORR.
Originality/value
The method for the synthesis of bio-inspired electrocatalyst was novel and can find numerous applications in industries, especially as ORR non-precious metal catalyst.
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Ibrahim A. Amar and Mohammed M. Ahwidi
This paper aims to investigate the electrocatalytic activity of CoFe1.9Mo0.1O4-Ce0.8Gd0.18Ca0.02O2-δ composite (CFMo-CGDC) for the direct synthesis of ammonia from H2O and N2…
Abstract
Purpose
This paper aims to investigate the electrocatalytic activity of CoFe1.9Mo0.1O4-Ce0.8Gd0.18Ca0.02O2-δ composite (CFMo-CGDC) for the direct synthesis of ammonia from H2O and N2 under atmospheric pressure.
Designs
CoFe1.9Mo0.1O4 nanoparticles (CFMo NPs) were synthesized via a sol-gel method. CFMo NPs were characterized using X-ray diffraction (XRD), Brunauer–Emmet–Teller (BET) specific surface area measurement and scanning electron microscope (SEM). Double-chamber reactor was used to synthesize ammonia using H2O and N2 as precursors. The factors affecting the ammonia formation rate (applied voltage and temperature) were studied.
Findings
CoFe1.9Mo0.1O4 nanoparticles (CFMo NPs) were synthesized via a sol-gel method. CFMo NPs were characterized using XRD, Brunauer–Emmet–Teller (BET) specific surface area measurement and SEM. Double-chamber reactor was used to synthesize ammonia using H2O and N2 as precursors. The factors affecting the ammonia formation rate (applied voltage and temperature) were studied.
Originality/value
The usage of CFMo-CGDC composite as an electrocatalyst for the synthesis of ammonia directly from H2O and N2.
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Zeinab Abdel Hamid, H.B. Hassan and Mohamed Sultan
The improvement of the hydrogen evolution reaction (HER) performance requires more efficient and inexpensive electrocatalysts. The purpose of this study is to prepare Ni-W and…
Abstract
Purpose
The improvement of the hydrogen evolution reaction (HER) performance requires more efficient and inexpensive electrocatalysts. The purpose of this study is to prepare Ni-W and Ni-W-P thin films using the electrodeposition technique using a pulse current and investigate their behaviors toward HER in an acidic solution.
Design/methodology/approach
The aim is to prepare Ni-W and Ni-W-P films by the electrodeposition technique using a pulse current and estimate their performance for the HER. The surface morphologies and chemical compositions of the deposited films were assessed using scanning electron microscopy, energy-dispersive X-ray analysis and X-ray diffraction. Linear sweep voltammetry, chronoamperometry, Tafel plots and electrochemical impedance spectroscopy were used to evaluate the prepared electrodes toward the hydrogen evolution process.
Findings
The main conclusion is that the surface morphology of Ni–W deposited film is a crystalline structure, while that of Ni-W-P deposit is an amorphous structure. HER activity on Ni-W electrodes increases with decreasing the Wt.% of W to 7.83 Wt.% in the prepared electrodes. In addition, the presence of P enhances HER activity, which increases with increasing the Wt.% of P in the prepared Ni-W-P electrodes. Both Ni-W (7.83 Wt.% W) and Ni-W-P (20.34 Wt.% P), which have been prepared at 8 A dm−2 display the best performance toward HER compared to the other prepared electrodes. They exhibit high catalytic activities toward HER, which is evidenced by high hydrogen evolution current density values of 9.52 and 33.98 mA cm−2, low onset potentials of −0.73 and −0.63 V, low Tafel slopes of −125 mV/dec, high exchange current densities of 0.058 and 0.20 mA cm−2, low charge transfer resistances (Rct) of 226.28 and 75.8 ohm·cm2 for Ni-W (7.83 Wt.% W) and Ni-W-P (20.34 Wt.% P), respectively; moreover, they exhibited considerable stabilities too.
Originality/value
The results presented in this work are an insight into understanding the performance of the prepared Cu electrodes coated by Ni-W and Ni-W-P films toward HER. In this work, a consistent assessment of the results achieved on laboratory scale has been conducted.
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Abstract
Purpose
The purpose of this paper was to provide a simple method for the preparation of carbon nanotubes (CNTs) by pyrolysing sunflower seed hulls and sago and to evaluate the application of such CNTs in supercapacitors.
Design/methodology/approach
The CNTs were obtained by pyrolysing sunflower seed hulls and sago at 800°C. The prepared CNTs were studied by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, cyclic voltammograms, galvanostatic charge and discharge and electrochemical impedance spectra methods.
Findings
The CNTs had large surface areas as determined by the methylene blue method and the Brunauer – Emmett – Teller method. And the CNTs that were prepared by pyrolysing the natural sunflower seed hulls (denoted as CNTs-1) and sago (denoted as CNTs-2) had capacitances of 86.9 F/g and 26.7 F/g, respectively.
Research limitations/implications
The capacitances of CNTs can be further improved.
Practical implications
The exceptional electronic and mechanical properties of CNTs prepared lend the CNTs to diverse applications including electrocatalysts, hydrogen storage, photovoltaic devices actuators, energy storage, field-emitting flat panel displays and composites.
Originality/value
Currently, CNTs have not yet been used in the industry at a mass production scale due to high costs associated. The outcomes of the study reported in this article could provide a convenient method in aid of industrialisation of the production of CNTs.
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Sajad Pirsa and Fahime Purghorbani
In this study, an attempt has been made to collect the research that has been done on the construction and design of the H2O2 sensor. So far, many efforts have been made to…
Abstract
Purpose
In this study, an attempt has been made to collect the research that has been done on the construction and design of the H2O2 sensor. So far, many efforts have been made to quickly and sensitively determine H2O2 concentration based on different analytical principles. In this study, the importance of H2O2, its applications in various industries, especially the food industry, and the importance of measuring it with different techniques, especially portable sensors and on-site analysis, have been investigated and studied.
Design/methodology/approach
Hydrogen peroxide (H2O2) is a very simple molecule in nature, but due to its strong oxidizing and reducing properties, it has been widely used in the pharmaceutical, medical, environmental, mining, textile, paper, food production and chemical industries. Sensitive, rapid and continuous detection of H2O2 is of great importance in many systems for product quality control, health care, medical diagnostics, food safety and environmental protection.
Findings
Various methods have been developed and applied for the analysis of H2O2, such as fluorescence, colorimetry and electrochemistry, among them, the electrochemical technique due to its advantages in simple instrumentation, easy miniaturization, sensitivity and selectivity.
Originality/value
Monitoring the H2O2 concentration level is of practical importance for academic and industrial purposes. Edible oils are prone to oxidation during processing and storage, which may adversely affect oil quality and human health. Determination of peroxide value (PV) of edible oils is essential because PV is one of the most common quality parameters for monitoring lipid oxidation and oil quality control. The development of cheap, simple, fast, sensitive and selective H2O2 sensors is essential.
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The paper introduces a microwave and electrochemical-assisted method for synthesis of chlorine-derived iron phthalocyanine pigment and oxygen reduction reaction catalyst…
Abstract
Purpose
The paper introduces a microwave and electrochemical-assisted method for synthesis of chlorine-derived iron phthalocyanine pigment and oxygen reduction reaction catalyst nanoparticles. The aims of this study are to investigate the possibility of nano-scale particle size (<35 nm), high-efficiency product reaction, remove acidic wastewater, time optimization and maximize number of chlorine on aromatic rings.
Design/methodology/approach
The paper presents a combined synthesis technique, which does not have the problems of the conventional methods. Chlorinated iron phthalocyanine nanoparticles have been fabricated using phthalic anhydride, urea (high purity), electrochemical-generated iron (II) cations and microwave irradiation as promoter. The approach yields a product of high quality, uniform particle size distribution and high efficiency and that was environment-friendly.
Findings
The particle size and time needed for the production of chlorinated iron phthalocyanine were about 35 nm and 7 min, respectively.
Research limitations/implications
The catalyst, that is used in this method, should be weighed carefully. In addition, the solvent should be a saturated solution of NaCl in water.
Practical implications
The method provides a simple and practical solution to improving the synthesis of an iron-based catalyst for oxygen reduction reaction.
Originality/value
The combined method for synthesis of chlorinated iron phthalocyanine was novel and can find numerous applications in the industry, especially as an oxygen reduction reaction non-precious metal catalyst.
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City Technology is one company that seems to know how to run a sensor manufacturing business, as Stephen McClelland explains.
Kaushik Alayavalli and David L. Bourell
The purpose of this paper is to produce electrically conductive, fluid impermeable graphite bipolar plates for a direct methanol fuel cell, using indirect selective laser…
Abstract
Purpose
The purpose of this paper is to produce electrically conductive, fluid impermeable graphite bipolar plates for a direct methanol fuel cell, using indirect selective laser sintering (SLS) and suitable post processing techniques.
Design/methodology/approach
Bipolar plates are made by the indirect SLS of graphite powder and phenolic resin mixture. The phenolic resin binder is then burnt off at a high temperature in a vacuum furnace to produce a 100 per cent carbon part. This brown part is then infiltrated using a low‐viscosity (∼5‐10 cps) cyanoacrylate to seal up the open pores, rendering the plates fluid impermeable.
Findings
It has been found that the electrical conductivity increases significantly (> 220 S/cm) with a corresponding increase in pyrolyzing temperature which correlates well with literature on the carbonization of phenol formaldehyde resins. The cyanoacrylate infiltrated parts tested under fluid pressure demonstrated no leakage through the plate, indicating full closure of open porosity.
Originality/value
This work demonstrates the capability of the SLS process to produce working bipolar plates with complex flow field designs that can be tested to verify its efficacy in a working fuel cell, thereby saving time and cost in machining natural graphite.
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Reetu Yadav, Mamta Kushwah, Anna Nikolaevna Berlina and Mulayam Singh Gaur
The purpose of this study is determination of cadmium using silver-gold bimetallic nanoparticles (Ag-Au BMNPs) and an aptamer modified glassy carbon electrode.
Abstract
Purpose
The purpose of this study is determination of cadmium using silver-gold bimetallic nanoparticles (Ag-Au BMNPs) and an aptamer modified glassy carbon electrode.
Design/methodology/approach
The maximum response of modified electrode was obtained with, 50 mV pulse amplitude, 20 mV/s scan rate in phosphate buffer of pH 4.0. Ag-Au BMNPs, as the mediators improved electron transmit during the entire electron transfer process and the aptasensor response. Herein, the authors used aptamer as the capture probe to prepare an aptasensor with enhanced stability.
Findings
The proposed aptasensor exhibited a wide linearity to cadmium in the range of 0.001–0.100 µg/L with a low detection limit of 0.005×10−3 µg/L. The glassy carbon electrodes with Ag-Au BMNPs showed a lower detection limit.
Originality/value
This aptasensor has good reproducibility, stability and repeatability and is cost-effective to regenerate. The specificity and selectivity of the novel modified electrode is tested in the presence of other interfering metal ions such as Fe2+, Mn2+, Mg2+, Sb3+ and Bi3+. The aptasensor shows 10 times more sensitivity and selectivity for Cd2+ ions.
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Hadeel Alhazimeh, Mohamed Ghazi Al-Fandi and Lina M.K. Al-Ebbini
Ascorbic acid (AA) is an essential vitamin for human health. Therefore, fast and cost-effective detecting of AA is essential, whether in human or food samples. The purpose of this…
Abstract
Purpose
Ascorbic acid (AA) is an essential vitamin for human health. Therefore, fast and cost-effective detecting of AA is essential, whether in human or food samples. The purpose of this paper is to develop an electrochemical nanosensor for AA detection.
Design/methodology/approach
The proposed nanosensor was developed by printing carbon nanoparticles ink and silver nanoparticles ink on a polydimethylsiloxane (PDMS) substrate. The surface of the PDMS substrate was first treated by corona plasma. Then, the nanomaterials printer was used to deposit both inks on the substrate. The working electrode surface was modified by drop-casting of carbon nanotubes. Morphological evaluation was applied using scanning electron microscopy and cyclic voltammetry. Also, a potentiostat was used to detect AA by differential pulse voltammetry.
Findings
It has been shown that the developed nanosensor linearly worked at a range of (0–5 mM), with a limit of detection lower than 0.8 mM and a relative standard deviation of 6.6%.
Originality/value
The developed nanosensor is characterized by a simple and cost-effective sensing tool for AA. In particular, the nanomaterials enhanced the nanosensor’s sensitivity due to the high catalytic activity.
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