scholarly journals ELECTROCATALYSIS OF THE HYDROGEN EVOLUTION REACTION ON CoRe, CoWRe SUPERALLOYS DEPOSITED FROM CITRATE ELECTROLYTE

2020 ◽  
Vol 86 (9) ◽  
pp. 28-38
Author(s):  
Yuliya Yapontseva ◽  
Tetiana Maltseva ◽  
Valeriy Kublanovsky
Keyword(s):  
Hydrogen Evolution Reaction ◽  
Alkaline Solution ◽  
Current Density ◽  
Hydrogen Reduction ◽  
Ternary Alloys ◽  
Hydrogen Ions ◽  
Citrate Electrolyte ◽  
Order Of Magnitude ◽  
Rhenium Content ◽  
Deposition Current Density

The reaction of electroreduction of hydrogen ions on binary CoRe and ternary CoWRe alloys electrodeposited from a citrate electrolyte with different amount of potassium perrhenate (0.01 and 0.05 mol·L-1) depending on the deposition current density (5–40 A·cm-2) has been investigated by the method of stationary voltammetry. The kinetic parameters of the reaction have been calculated, and it is shown that the use of ternary alloys allows one to increase the value of exchange current density by almost an order of magnitude and significantly reduce the overvoltage of hydrogen reduction in comparison with cobalt. It is shown that the best electrocatalysts for the reduction of hydrogen in alkaline solution can be ternary CoWRe alloys with a rhenium content of 15–20 at. %.

scholarly journals PECULIARITIES OF ELECTRODEPOSITION OF COBALT—WOLFRAM—RENIUM ALLOY

2019 ◽  
Vol 85 (2) ◽  
pp. 80-87
Author(s):  
Yuliya Yapontseva ◽  
Valeriy Kublanovsky ◽  
Tetiana Maltseva
Keyword(s):  
Corrosion Resistance ◽  
Current Density ◽  
Hydrogen Reduction ◽  
Reduction Reaction ◽  
Neutral Medium ◽  
Limiting Stage ◽  
Deposition Processes ◽  
Hydrogen Overpotential ◽  
Rhenium Content ◽  
Deposition Current Density

The methods of stationary voltammetry and chronovoltammetry have been used to study deposition processes of ternary CoWRe alloys at different rhenium content of the electrolyte and deposition current density. It has been found that the limiting currents have a diffusive nature and are proportional to the concentration of perrhenate ions in the electrolyte.  The CoWRe alloys should be formed by the discharge of bimetallic citrate complexes of the following composition [(Co)(WO4)(H)(Cit)]2- and rhenium electrodeposition. Rhenium does not form complexes with citrate ions and deposits better in an alloy with iron group metals than in the form of an individual metal from a perrhenate solution. It can be assumed that the discharge of rhenium into the alloy occurs from a surface complex, the nature of which has not yet been established. The alloy current efficiency reaches 93% due to the high overpotential of hydrogen evolution on the alloy surface. According to the results of investigations of the catalytic properties of alloys in the hydrogen reduction reaction, it has been found that with increasing the rhenium content of the electrolyte and alloy, an increase in hydrogen overpotential is observed. Based on the Tafel coefficients found, it was found that in an acidic and neutral medium, the limiting stage of the cathodic and anodic reaction is the transfer of the first electron. In an alkaline medium, the anode process is complicated by the simultaneous transport of two electrons. The found values of corrosion resistance are 1-2 kOm·cm-2 in solutions of 0.01 M H2SO4; 20-110 kOm·cm-2 in 2.5% NaCl; 10-30 kOm·cm-2 in 1.0 M KOH. Based on the dependence of corrosion resistance on the refractory metals content of the alloy and the electrodeposition conditions, the optimum deposition current density of 10 mA·cm-2 has been found.

scholarly journals Facile Synthesis of PdCuRu Porous Nanoplates as Highly Efficient Electrocatalysts for Hydrogen Evolution Reaction in Alkaline Medium

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1451
Author(s):  
Changhong Chen ◽  
Ningkang Qian ◽  
Junjie Li ◽  
Xiao Li ◽  
Deren Yang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Alkaline Solution ◽  
Current Density ◽  
Alkaline Media ◽  
Water Dissociation ◽  
Galvanic Replacement ◽  
Facile Synthesis ◽  
Better Than

Ru is a key component of electrocatalysts for hydrogen evolution reaction (HER), especially in alkaline media. However, the catalytic activity and durability of Ru-based HER electrocatalysts are still far from satisfactory. Here we report a solvothermal approach for the synthesis of PdCuRu porous nanoplates with different Ru compositions by using Pd nanoplates as the seeds. The PdCuRu porous nanoplates were formed through underpotential deposition (UPD) of Cu on Pd, followed by alloying Cu with Pd through interdiffusion and galvanic replacement between Cu atoms and Ru precursor simultaneously. When evaluated as HER electrocatalysts, the PdCuRu porous nanoplates exhibited excellent catalytic activity and durability. Of them, the Pd24Cu29Ru47/C achieved the lowest overpotential (40.7 mV) and smallest Tafel slope (37.5 mV dec−1) in an alkaline solution (much better than commercial Pt/C). In addition, the Pd24Cu29Ru47/C only lost 17% of its current density during a stability test for 10 h, while commercial Pt/C had a 59.5% drop under the same conditions. We believe that the electron coupling between three metals, unique porous structure, and strong capability of Ru for water dissociation are responsible for such an enhancement in HER performance.

scholarly journals ELECTROCATALYTIC COBALT-VANADIUM COATINGS FOR THE HYDROGEN EVOLUTION REACTION

2021 ◽  
pp. 67-71
Author(s):  
Mykola Sakhnenko ◽  
Yulia Zhelavska ◽  
Svitlana Zyubanova ◽  
Valeriia Proskurina
Keyword(s):  
Catalytic Activity ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Hydrogen Reduction ◽  
Alloy Coating ◽  
Vanadium Content ◽  
Hydrogen Energy ◽  
Vanadium Alloy ◽  
Citrate Electrolyte ◽  
Steel 20

The study of existing energy-saving materials and obtaining the new ones for reducing the cost of the hydrogen production, is relevant for modern hydrogen energy industry. Such properties can be predicted for materials containing vanadium, molybdenum, tungsten and exhibiting catalytic activity for the hydrogen evolution reaction Aforementioned metals can be co-deposited from aqueous solutions with iron subgroup metal-catalysts through the formation of cluster intermetallic compounds with Me-V bond adsorbed on the cathode surface.  The induced co-deposition of cobalt with vanadium from the complex citrate electrolyte was investigated in the current work. As a result of the research, it was found that the uniform microcrystalline light-gray high-quality cobalt-vanadium alloy coating is possible to precipitate from a citrate electrolyte with content of 20 g/dm3 vanadium (in terms of metal) as a citrate complex The process was carried out at a current density of 5–10 A/dm2, at a temperature of 30–40°С, pH = 2,8–3,2. The content of vanadium in the coating is 0,37–0,53 % by weight. The maximum vanadium content in the coating is observed at current densities 8–9 А/dm2. The catalytic activity study of the coating that was obtained using cobalt-vanadium alloy in the reaction of hydrogen reduction at the cathode was performed in solution of 2,5М NaOH + 0,02 M NaCl. By increasing the vanadium content in the coating from 0,37 to 0,53% the hydrogen evolution overvoltage is reduced by 0,5 V. It was found that the overvoltage of the hydrogen ion evolution reaction on cathodes from steel 20 with cobalt-vanadium coating is 0.08–0,1 V lower, and the exchange current is higher than on electrodes made of steel 20, which are used in industrial water-alkali electrolysis. This indicates the electrocatalytic activity of the investigated materials for the hydrogen evolution reaction. Electrodes with coating, obtained by cobalt-vanadium alloy can be recommended as a cathode material for the hydrogen electrochemical production. Hydrogen evolution overvoltage reduction also decrease the energy consumption for this process by 15–20 %.

The Influence of Temperature of Electrodeposition on the Electrochemical Properties of Ni Coatings

2015 ◽  
Vol 228 ◽  
pp. 242-245
Author(s):  
Magdalena Popczyk ◽  
Bożena Łosiewicz
Keyword(s):  
Electrochemical Properties ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Current Density ◽  
Room Temperature ◽  
Steel Substrate ◽  
Influence Of Temperature ◽  
Surface Development ◽  
Deposition Current Density

Porous Ni coatings were prepared by galvanostatic electrodeposition on the steel substrate from the Watts type bath at the deposition current densityjdep= -250 mA cm2at the temperature 40, 50 and 60°C. Investigations of hydrogen evolution reaction (HER) on the obtained Ni electrodes were carried out in 5 M KOH solution at room temperature. It was found that with the increase in the electrodeposition temperature of the coatings, the activity of the Ni electrocatalysts towards the HER decreased due to diminishing surface development of the Ni coatings.

A CoMoO4–Co2Mo3O8 heterostructure with valence-rich molybdenum for a high-performance hydrogen evolution reaction in alkaline solution

2019 ◽  
Vol 7 (28) ◽  
pp. 16761-16769 ◽  
Author(s):  
Zheng Liu ◽  
Changhong Zhan ◽  
Linkai Peng ◽  
Yang Cao ◽  
Yong Chen ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Alkaline Solution ◽  
High Performance ◽  
Hydrogen Reduction ◽  
Intrinsic Activity ◽  
Step Method ◽  
Hierarchical Nanostructures ◽  
Reduction Treatment

The heterostructure CoMoO4–Co2Mo3O8 was prepared by a two-step method, including hydrothermal synthesis of CoMoO4 nanowire and subsequent hydrogen reduction treatment of CoMoO4. Due to hierarchical nanostructures of CoMoO4–Co2Mo3O8 facilitated intrinsic activity and conductivity, the outstanding performance for HER, surpassing most cobalt–molybdenum bimetal oxide.

scholarly journals Microwave-Assisted vs. Conventional Hydrothermal Synthesis of MoS2 Nanosheets: Application towards Hydrogen Evolution Reaction

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1040 ◽  
Author(s):  
Getachew Solomon ◽  
Raffaello Mazzaro ◽  
Vittorio Morandi ◽  
Isabella Concina ◽  
Alberto Vomiero
Keyword(s):  
Hydrothermal Synthesis ◽  
Hydrothermal Method ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Current Density ◽  
Crystal Morphology ◽  
Synthesis Method ◽  
Synthesis Methods ◽  
Mos2 Nanosheets ◽  
Microwave Assisted

Molybdenum sulfide (MoS2) has emerged as a promising catalyst for hydrogen evolution applications. The synthesis method mainly employed is a conventional hydrothermal method. This method requires a longer time compared to other methods such as microwave synthesis methods. There is a lack of comparison of the two synthesis methods in terms of crystal morphology and its electrochemical activities. In this work, MoS2 nanosheets are synthesized using both hydrothermal (HT-MoS2) and advanced microwave methods (MW-MoS2), their crystal morphology, and catalytical efficiency towards hydrogen evolution reaction (HER) were compared. MoS2 nanosheet is obtained using microwave-assisted synthesis in a very short time (30 min) compared to the 24 h hydrothermal synthesis method. Both methods produce thin and aggregated nanosheets. However, the nanosheets synthesized by the microwave method have a less crumpled structure and smoother edges compared to the hydrothermal method. The as-prepared nanosheets are tested and used as a catalyst for hydrogen evolution results in nearly similar electrocatalytic performance. Experimental results showed that: HT-MoS2 displays a current density of 10 mA/cm2 at overpotential (−280 mV) compared to MW-MoS2 which requires −320 mV to produce a similar current density, suggesting that the HT-MoS2 more active towards hydrogen evolutions reaction.

Critical current density and microstructure variations in YBa2Cu3O7−x + BaSnO3 films with different concentrations of BaSnO3

2008 ◽  
Vol 23 (12) ◽  
pp. 3363-3369 ◽  
Author(s):  
C.V. Varanasi ◽  
J. Burke ◽  
L. Brunke ◽  
H. Wang ◽  
J.H. Lee ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Gradual Increase ◽  
Critical Transition ◽  
Critical Transition Temperature ◽  
Transmission Electron ◽  
Order Of Magnitude ◽  
High Fields ◽  
Magnitude Increase

Previous work on YBa2Cu3O7−x (YBCO) + BaSnO3 (BSO) films with a single composition showed significant critical current density (Jc) improvements at higher fields but lowered Jc in low fields. A detailed study on BSO concentrations provided here demonstrates that significant Jc enhancement can occur even up to 20 mol% BSO inclusion, where typical particulate inclusions in these concentrations degrade the YBCO performance. YBCO + BSO films were processed on (100) LaAlO3 substrates using premixed targets of YBa2Cu3O7-x (YBCO) with additions of 2, 4, 10, and 20 mol% BSO. The critical transition temperature Tc of the films remained high (>87 K), even with large amounts (20 mol%) of BSO. YBCO + BSO films showed a gradual increase in Jc at high fields as the amount of BSO was increased. More than an order of magnitude increase in Jc was measured in YBCO + BSO samples as compared to regular YBCO at 4 T. YBCO + 10 mol% BSO films showed overall improvement at all the field ranges while YBCO + 20 mol% BSO was better only at high fields. Transmission electron microscopy revealed the presence of ∼7–8-nm-diameter BSO nanocolumns, the density of which increased with increasing BSO content correlating well with the observed improvements in Jc.

Iron phosphide nanoparticles as an efficient electrocatalyst for the OER in alkaline solution

2016 ◽  
Vol 4 (25) ◽  
pp. 9750-9754 ◽  
Author(s):  
J. Masud ◽  
S. Umapathi ◽  
N. Ashokaan ◽  
M. Nath
Keyword(s):  
Oxygen Evolution ◽  
Alkaline Medium ◽  
Alkaline Solution ◽  
Current Density ◽  
Exchange Current ◽  
Exchange Current Density ◽  
Iron Phosphide ◽  
Onset Potential ◽  
Low Overpotential

Ultrasmall FeP nanoparticles have been reported as an efficient oxygen evolution electrocatalyst in alkaline medium with low onset potential for oxygen evolution and require low overpotential to reach 10 mA cm−2 exchange current density.

Sign in / Sign up

Export Citation Format

Share Document