Incorporation effect of nanosized perovskite LaFe0.7Co0.3O3 on the electrochemical activity of Pt nanoparticles-multi walled carbon nanotube composite toward methanol oxidation

Enhanced electrocatalytic activity of Pt-SnO2 nanoparticles supported on natural bentonite-functionalized reduced graphene oxide-extracted chitosan from shrimp wastes for methanol electro-oxidation

In this work, tin (IV) oxide (SnO₂) nanoparticles were synthesized based on Amaranthus spinosus plant. The produced graphene oxide by a modified Hummers' method was functionalized with melamine (mRGO) and used accompanied by natural bentonite (Bnt) and extracted chitosan from shrimp wastes to prepare Bnt-mRGO-CH. This was utilized as novel support for anchoring Pt and SnO₂ nanoparticles to prepare the novel Pt-SnO₂/Bnt-mRGO-CH catalyst. The crystalline structure, morphology and uniform dispersion of nanoparticles in the prepared catalyst were determined by TEM images and XRD technique. The electrocatalytic performance of the Pt-SnO₂/Bnt-mRGO-CH catalyst was evaluated for methanol electro-oxidation through electrochemical investigations including cyclic voltammetry, electrochemical impedance spectroscopy, and chronoamperometry techniques. Pt-SnO₂/Bnt-mRGO-CH showed enhanced catalytic activity compared to Pt/Bnt-mRGO-CH and Pt/Bnt-CH catalysts considering its higher electrochemically active surface area, higher mass activity, and better stability for methanol oxidation. SnO₂/Bnt-mRGO and Bnt-mRGO nanocomposites were also synthesized and did not show any significant activity for methanol oxidation. The results showed that Pt-SnO₂/Bnt-mRGO-CH could be a promising catalyst as anode material in direct methanol fuel cells.

Sonochemical synthesis of high-performance Pd@CuNWs/MWCNTs-CH electrocatalyst by galvanic replacement toward ethanol oxidation in alkaline media

In this paper, a fast and effective method for the palladium (Pd) wire nanostructures synthesis with the great surface area through galvanic replacement reaction utilizing copper nanowires (CuNWS) as a template by the assistance of ultrasound under room temperature condition is proposed. A multifunctional catalyst with the mentioned nanostructure, Pd@CuNWs, and multi walled carbon nanotubes (MWCNTs) and chitosan (CH) as a binder was fabricated. To investigate the morphology and bulk composition of the prepared catalyst, Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Powder Diffraction (XRD), and Inductively Coupled Plasma atomic Emission Spectroscopy (ICP-AES) were utilized. Various electrochemical techniques including chronoamperometry and cyclic voltammetry were employed for the electrocatalytic activity of ethanol electrooxidation and durability in basic solution. Electrochemical catalytic activity and durability evaluation results proved that the as-synthesized Pd@CuNWs/MWCNTs-CH has a super electrocatalytic activity compared to Pd/MWCNTs and Pd/C electrocatalysts for ethanol electrooxidation. Pd@CuNWs/MWCNTs-CH catalyst demonstrated substantially enhanced performance and long-term stability for ethanol electrooxidation in the basic solution in comparison to Pd/MWCNTs and commercial Pd/C demonstrated the potential in utilizing Pd@CuNWs/MWCNTs-CH as an efficient catalyst for ethanol oxidation. Additionally, thermodynamic and kinetic evaluations revealed that the Pd@CuNWs/MWCNTs-CH catalyst has lower activation energy compared to Pd/MWCNTs and Pd/C which leads to a lower energy barrier and an excellent charge transfer rate towards ethanol oxidation. Noticeably, the Pd@CuNWs/MWCNTs-CH presented excellent catalytic activities with high peak current density which was 9.5 times more than Pd/C, and more negative onset potential in comparison to Pd/C is acquired for ethanol electrooxidation denoting synergistic effect between CuNWs/MWCNs-CH and Pd. The Pd@CuNWs/MWCNTs-CH can be considered as a valid candidate among available electrocatalysts in direct ethanol fuel cells (DEFCs).

New synthesis of poly ortho-methoxyaniline nanostructures and its application to construct modified multi-wall carbon nanotube/graphite paste electrode for simultaneous determination of uric acid and folic acid

Uric acid (UA) and folic acid (FA) are compounds of biomedical interest. In humans, about 70% of daily uric acid disposal occurs via the kidneys, and in 5–25% of humans, impaired renal (kidney) excretion leads to hyperuricemia. Folate is another form folic acid of which is known as, is one of the B vitamins. It is used as a supplement by women to prevent neural tube defects developing during pregnancy. Polyortho-methoxyaniline nanostructures (POMANS) was synthesized with a new two phase (organic-water) synthesis method. The POMANS was characterized using transmission electron microscopy (TEM) and Fourier transform IR (FTIR). This polymer was used to construct a modified multi-wall carbon nanotube, graphite paste electrode (POMANS-MWCNT/GPE). Linear sweep voltammograms (LSV), cyclic voltammetry (CV) and chronoamperometry were used to investigate the suitability of polyortho-methoxyaniline with multi-wall carbon nanotubes paste electrode as a modifier for the electrocatalytic oxidation of UA and FA in aqueous solutions with various pHs. The results showed that POMANS-MWCNT/GPE had high anodic peak currents for the electrooxidation of UA and FA in pH 6.0.Under the optimized conditions, The catalytic peak currents obtained, was linearly dependent on the UA and FA concentrations in the range of 0.6–52 and 0.5–68 μM with two segments and the detection limits 0.157 and 0.113 μM for UA and FA were, respectively. Finally, the proposed method was also examined as a sensitive, simple and inexpensive electrochemical sensor for the simultaneous determination of UA and FA in real samples such as urine and serum.

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For the first time, POMANS was synthesized with a new method of two-phase organic & water.

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POMANS-MWCNT/GPE was used for simultaneous determination of UA and FA at optimum pH 6.0.

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Parameters n and α were also determined for UA and FA.

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Electrochemical simultaneous determination of UA and FA with modified electrode real samples.

Fabrication and performance evaluation of a novel membrane electrode assembly for DMFCs

In this study, a new GDL was prepared using graphene–PVC–PANI and teflonated carbon cloth. PdNPs and nanosized LaNi_0.5Fe_0.5O₃NPs-CH was synthesized. A DMFC were designed, assembled and tested with the suggested nanoparticles and GDL.