scholarly journals Enhancing Activity of Pd-Based/rGO Catalysts by Al-Si-Na Addition in Ethanol Electrooxidation in Alkaline Medium

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Minh Dang Nguyen ◽  
Lien Thi Tran ◽  
Quang Minh Nguyen ◽  
Thao Thi Nguyen ◽  
Thu Ha Thi Vu
Keyword(s):  
Alkaline Medium ◽  
Current Density ◽  
Active Phase ◽  
Pd Nanoparticles ◽  
Electrochemical Stability ◽  
Ethanol Electrooxidation ◽  
Peak Current Density ◽  
Direct Ethanol Fuel Cell ◽  
Reduced Graphene ◽  
The Stability

The article presents modified Pd-based catalysts supported on reduced graphene oxide (rGO), used in the electrooxidation reaction of ethanol in alkaline medium. When NaBH4 reducing agent was used, the random presence of Na was found out. According to this result, Na was used as a promoter of Pd-based catalyst. Consequently, the Al-Si-Na addition not only assisted active phase Pd nanoparticles to disperse homogenously on graphene surport, but also contributed to increase catalytic activity in the reaction. This value, 16138 mA·mg−1Pd, is about 1.5 times higer than that of the catalyst modified by Al-Si. Moreover, the stability of the catalyst is enhanced more. The electrochemical stability of PASGN.N catalyst was relatively good: after 500 scanning cycles, the current density diminished 32% compared with the highest peak current density of the 15th cycle, which was chosen as a reference. These significant improvement results in electrooxidation of ethanol have opened up the high potential application of these catalysts in direct-ethanol fuel cell.

Research on Junction Termination Protection Technology for 3.3 kV Power Devices

2013 ◽  
Vol 433-435 ◽  
pp. 1486-1491
Author(s):  
Hai Long Bao ◽  
Yue Yang Liu ◽  
Wen Yu Gao ◽  
Yao Hua Wang ◽  
Rui Jin ◽  
...  
Keyword(s):  
Electric Field ◽  
Breakdown Voltage ◽  
Current Density ◽  
Impact Ionization ◽  
Necessary Condition ◽  
Power Devices ◽  
Peak Current Density ◽  
Protection Technology ◽  
The Stability ◽  
Peak Electric Field

The necessary condition for power devices with enough blocking properties is Junction termination technology. In this paper, starting with the dose of rings, 3.3 kV Floating Filed Rings was investigated, and the influence of electric field and current density on the breakdown characteristic is also described. The results show that the dose of field rings directly affects the stability of breakdown voltage, this impact is relevant to the location of the peak electric field and the peak current density when breakdown was occurred. When the peak electric field appears in the middle of the field rings, the breakdown voltage is not sensitive to the dose of rings; however, when the peak electric field and strongest current density appeared on the edge of termination at the same time, breakdown voltage become very sensitive to the dose of rings because of the highest impact ionization in this position. Simulations and experiments indicate that the junction termination has better withstand voltage stability , when electric field distributes uniformly, the position of breakdown is in the middle of the termination, and the strongest current density appears in the main junction.

scholarly journals NiOOH/FeOOH Supported on Reduced Graphene Oxide Composite Electrodes for Ethanol Electrooxidation

2020 ◽  
Vol 2 (1) ◽  
pp. 17
Author(s):  
João Pedro Jenson de Oliveira ◽  
Acelino Cardoso de Sá ◽  
Leonardo Lataro Paim
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Alkaline Medium ◽  
Potential Range ◽  
Composite Electrodes ◽  
Ethanol Electrooxidation ◽  
Reduction Potentials ◽  
Reduced Graphene ◽  
Surface Modified ◽  
Electrodeposition Of Metals

In this work, nickel (Ni) and Ni-Fe bimetallic microparticles were electrosynthesized at reduction potentials in the range from −0.70 V to −1.20 V (50 mV s−1) by cyclic voltammetry (CV) onto graphite/paraffin electrode surface modified with nanosheets of reduced graphene oxide (RGO). Previously, the RGO was electrodeposited by CV from a suspension of 1 mg mL−1 of graphene oxide in PBS solution with pH 9.18, in the potential range from −1.50 V to 0.50 V (10 mV s−1). After electrodeposition of metals, the oxyhydroxides were formed by CV in an alkaline medium of 0.10 mol L−1 of NaOH in the potential range from −0.20 V to 1.0 V (100 mV s−1) with successive scans until stabilization of currents. In order to characterize the developed electrodes composites, the surfaces were investigated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Electrochemical performance of the developed electrodes composites to ethanol electrooxidation was carried out in an alkaline medium of 0.10 mol L−1 of NaOH in the potential range from −0.20 V to 1.0 V (100 mV s−1) by CV. The electrodes were able to induce the electrooxidation of ethanol at a potential of 0.55 V for the electrode made of NiOOH/FeOOH and around of 0.60 V for the electrode modified with NiOOH.

Pd Nanoparticles-Supported Carbon Nanotube-Encapsulated NiO/MgO Composite as an Enhanced Electrocatalyst for Ethanol Electrooxidation in Alkaline Medium

2017 ◽  
Vol 2 (35) ◽  
pp. 11438-11444 ◽  
Author(s):  
Chinnathambi Mahendiran ◽  
Dhanushkotti Rajesh ◽  
Thandavarayan Maiyalagan ◽  
Kadirvelayutham Prasanna
Keyword(s):  
Carbon Nanotube ◽  
Alkaline Medium ◽  
Pd Nanoparticles ◽  
Ethanol Electrooxidation

The Effect of Ternary Catalyst Atomic Ratios (PtRuSn/C and PtRuNi/C) on Ethanol Electrooxidation for Direct Ethanol Fuel Cell

2015 ◽  
Vol 659 ◽  
pp. 247-251 ◽  
Author(s):  
Napha Sudachom ◽  
Chompunuch Warakulwit ◽  
Paweena Prapainainar
Keyword(s):  
Current Density ◽  
Bond Breaking ◽  
Ethanol Electrooxidation ◽  
Direct Ethanol Fuel Cell ◽  
Maximum Current Density ◽  
Maximum Current ◽  
High Maximum ◽  
Ternary Catalysts ◽  
Ternary Catalyst ◽  
Catalyst Dispersion

The effect of the different metal atomic ratios deposited on Vulcan XC-72R on ethanol electrooxidation reaction were investigated by producing of the ternary catalysts (PtRuSn/C and PtRuNi/C) in various atomic ratios (75:20:5, 75:15:10, 75:10:15, 75:5:20). All catalysts were prepared via polyol process. The nominal atomic ratios of the metals on the support were confirmed by EDX-SEM. The cyclic voltammetry was used to investigate the electrocatalytic activity of the catalysts. It was found that PtRuSn/C (75:10:15) showed the highest maximum current density of 3.25 mA/cm2 among all Sn containing catalysts. However, PtRuNi/C (75:5:20) also exhibited the high maximum current density of 2.66 mA/cm2 which was the maximum current density for Ni containing catalysts. Moreover, PtRuNi/C (75:5:20) exhibited the best activity and stability for ethanol electrooxidation reaction as showed in chronoamperometry tests. The current density at 3000 s was 0.54 mA/cm2. The size of the catalysts was about 1.9-3 nm measured by TEM. The catalyst also presented smaller particle size and better catalyst dispersion among all ternary catalysts. The addition of Sn facilitated the C-C bond breaking in molecule of ethanol while the addition of Ni facilitated better stability.

Binding of calcium and lead ions to carboxystarch prepared by action of nitrogen dioxide on native starch and its 2,3-dialdehyde derivatives

1986 ◽  
Vol 51 (6) ◽  
pp. 1340-1351 ◽  
Author(s):  
Rudolf Kohn ◽  
Karol Tihlárik
Keyword(s):  
Nitrogen Dioxide ◽  
Alkaline Medium ◽  
Binding Capacity ◽  
Lead Ions ◽  
Carbonyl Groups ◽  
Weakly Alkaline ◽  
Exchange Cations ◽  
Counter Ions ◽  
The Stability ◽  
Derivatives Of

The binding of calcium and lead ions to carboxy derivatives of starch prepared by allowing nitrogen dioxide to act on native maize starch (procedure A) and on starch 2,3-dialdehyde derivatives of degrees of oxidation DO(d.a.) ≥ 0.94 (procedure B) was studied. The carboxy group content of the samples in the H+ form was 4.6 - 12.1 mmol g-1. The effect of alkaline medium on the stability of the carboxy derivatives and on their ability to bind and exchange cations was examined. The Ca2+ → 2K+ exchange was evaluated in terms of the decrease in the electrostatic free enthalpy Δ(Gel/N)KCa, determined by alkalimetric potentiometric titrations, and the binding of Pb2+ ions was evaluated in terms of the activity of the Pb2+ counter-ions determined in suspensions of Pb salts of the carboxy derivatives by means of an ion specific electrode. The IR and CD spectra revealed that the carboxystarch preparations obtained by procedure A contained, in addition to free carboxy groups, a considerable amount of carbonyl groups. During the conversion of the latter groups to the former, even in a weakly alkaline medium, the carboxy derivatives undergo an appreciable degradation and lose, to a great extent, their ability to bind and exchange cations. Procedure B, on the other hand, leads to highly selective starch and amylose carboxy derivatives, exhibiting a small amount of carbonyl groups and featuring a relative stability towards alkaline medium; their binding capacity is as high as 12 milliequivalents of cations per g of sample.

scholarly journals Superior FexN electrocatalyst derived from 1,1′-diacetylferrocene for oxygen reduction reaction in alkaline and acidic media

2020 ◽  
Vol 9 (1) ◽  
pp. 843-852
Author(s):  
Hunan Jiang ◽  
Jinyang Li ◽  
Mengni Liang ◽  
Hanpeng Deng ◽  
Zuowan Zhou
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Current Density ◽  
Active Sites ◽  
Reduction Reaction ◽  
Alkaline Media ◽  
Acidic Media ◽  
Onset Potential ◽  
Acidic And Alkaline Media ◽  
The Stability

AbstractAlthough Fe–N/C catalysts have received increasing attention in recent years for oxygen reduction reaction (ORR), it is still challenging to precisely control the active sites during the preparation. Herein, we report FexN@RGO catalysts with the size of 2–6 nm derived from the pyrolysis of graphene oxide and 1,1′-diacetylferrocene as C and Fe precursors under the NH3/Ar atmosphere as N source. The 1,1′-diacetylferrocene transforms to Fe3O4 at 600°C and transforms to Fe3N and Fe2N at 700°C and 800°C, respectively. The as-prepared FexN@RGO catalysts exhibited superior electrocatalytic activities in acidic and alkaline media compared with the commercial 10% Pt/C, in terms of electrochemical surface area, onset potential, half-wave potential, number of electrons transferred, kinetic current density, and exchange current density. In addition, the stability of FGN-8 also outperformed commercial 10% Pt/C after 10000 cycles, which demonstrates the as-prepared FexN@RGO as durable and active ORR catalysts in acidic media.

B, N-codoped graphene nanoribbons supported Pd nanoparticles for ethanol electrooxidation enhancement

2016 ◽  
Vol 4 (13) ◽  
pp. 4929-4933 ◽  
Author(s):  
Qi Liu ◽  
Jinchen Fan ◽  
Yulin Min ◽  
Tong Wu ◽  
Yan Lin ◽  
...  
Keyword(s):  
Hydrothermal Method ◽  
Large Scale ◽  
Graphene Nanoribbons ◽  
Pd Nanoparticles ◽  
Ethanol Electrooxidation ◽  
One Pot ◽  
Supported Pd

In this study, B, N-codoped graphene nanoribbons (BN-GNRs) were prepared on a large scale via a one-pot hydrothermal method with GNRs and an ammonium fluoroborate (NH4BF4) mixture and served as the support for Pd loading targeted for efficient ethanol electrooxidation.

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