Electrodeposition of CoMo and CoMoP alloys from the weakly acidic solutions

Cesiulis, H.; Цынцару, Н.; Budreika, A.; Skridaila, N.

doi:10.3103/s1068375510050030

Cited by 26 publications

(15 citation statements)

References 28 publications

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“…[37]. Notable, in the case of Co-W alloys, the ECD for hydrogen evolution as a function of the W content denoted a minimum corresponding to a transition from polycrystalline to nanocrystalline structure, namely at around 25 at.% of W [38]. However, for similar tungsten content (~24e26 at.%) disagreeing results were obtained [39].…”

Section: Introductionmentioning

confidence: 99%

Electrodeposited tungsten-rich Ni-W, Co-W and Fe-W cathodes for efficient hydrogen evolution in alkaline medium

Vernickaite

Цынцару

Sobczak

et al. 2019

Electrochimica Acta

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The search of active, stable and cost-effective non-noble electrocatalysts for hydrogen evolution reaction (HER) is essential for sustainable energy systems. In this study, the electrodeposited Ni-W, CoW and FeW coatings having 5e30 at.% of W were examined as an alternative electrocatalysts for hydrogen evolution. The electrocatalytic efficiency of the electrodes was investigated on the basis of electrochemical data obtained from steady-state polarization technique in 30 wt% NaOH solution. It was found that with increasing of tungsten content in the deposits up to ~30 at.% a crystal-to-ultra-nanocrystalline transition takes place and the crystal grain size decreases up to 2e4 nm. The high content of W leads to course-grained coatings. These morphological and structural changes showed remarkable impact on the catalytic activity. The maximum catalytic performance was obtained for ultra-nanocrystalline W coatings. Among them the Ni-29at.%W demonstrated the highest apparent exchange current density (ECD) at the room temperature, i.e. 0.55 mA cm À2 , thus indicating more favorable hydrogen reduction. A significant improvement of catalytic activity of all tested cathodes with increasing the temperature of NaOH solution was noticed. Among investigated Co-33at.%W, Fe-30at.%W and Ni-29at.%W cathodes, the last one showed the best performance towards HER (ECD ¼ 14.5 mA cm À2 at 65 C).

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Section: Introductionmentioning

confidence: 99%

Electrodeposited tungsten-rich Ni-W, Co-W and Fe-W cathodes for efficient hydrogen evolution in alkaline medium

Vernickaite

Цынцару

Sobczak

et al. 2019

Electrochimica Acta

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“…They have found that an increase in the amount of Co and P precursors in the electrolyte increases the current density which in turn increases Co and P content in the deposit. The relative amount of tungsten in the deposit decreases because of the increased competition between P and W ions and easier transport of smaller P ion compared to W which in turn blocks the available sites for W. Similar behavior has also been observed in Co–Mo–P alloy and Ni–W–P coatings where increase in NaH 2 PO 2 concentration decreases Mo/W content and increases P content . In this context, it is worthwhile to compare our results with a similar alloy, like Co–Mo–P .…”

Section: Resultsmentioning

confidence: 99%

“…Comparison of electrodeposition of Co–Mo and Co–Mo–P alloys from weakly acidic solutions has shown that current efficiencies of the Co–Mo alloys are low while the deposition rates of the Co–Mo–P are sufficiently higher than binary Co–Mo. They have argued that NaH 2 PO 2 acts as an accelerator that changes the kinetics of Co and Mo codeposition . Prasad et al have claimed that Co–Mo–B coatings obtained from citrate based baths are found to have interesting properties such as high hardness, corrosion resistance, wear resistance and also sufficient ductility .…”

Section: Introductionmentioning

confidence: 99%

Effect of P codeposition on the structure and microhardness of Co–W coatings electrodeposited from gluconate bath

Seenivasan

Bera

2016

Surface & Interface Analysis

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Effects of addition of P to Co-W coatings from gluconate bath using direct current (DC) and pulse current (PC) methods have been investigated in this study. Co-W-P coatings with different P concentrations are prepared by varying hypophosphite concentration in the bath. Current efficiency of the Co-W-P electrodeposition is lower than that for Co-W coatings. Increase in NaH 2 PO 2 concentration increases the cobalt content significantly and decreases the tungsten content drastically. Co-W-P coatings display 'cauliflower-like' morphology and roughness of the coatings increases with increasing P content. As-deposited Co-W-P deposits are amorphous while heat treatment at different temperatures has rendered them crystalline with the precipitation of stable species like, Co 3 W, Co 2 P, etc. Unlike Co-W coatings, Co-W-P shows two-step crystallization in differential scanning calorimetry (DSC) and on heat treatment, which is similar to the behavior of Co-P electrodeposited from gluconate baths. Moreover, inclusion of phosphorous and heat treatment have led to significant increase in microhardness of the Co-W-P coatings. X-ray photoelectron spectroscopy (XPS) studies provide a detailed insight into the nature of Co, W and P species in as-deposited and sputtered coatings. Microhardness of the heat-treated coatings is higher than the as-deposited counterparts and is comparable with that of hard chromium.

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“…Co-Mo and Co-Mo-P alloys were precipitated from the citrate electrolyte at pH 4-6. Studies show that the value of hydrogen overvoltage on Co-Mo and Co-Mo-P is lower than of pure cobalt [140].…”

Section: Cobalt-based Electrodesmentioning

confidence: 89%

“…The choice of cobalt for the synthesis of cathode materials is accounted for by the interesting properties of cobalt alloys and by the easy release of hydrogen into them; the most popular are Co-Mo [132,133], Co-Cu [88], Co-Zn [89]. Co-Mo deposits were used as test objects in the electrolysis of water [134][135][136][137][138].…”

Section: Cobalt-based Electrodesmentioning

confidence: 99%

Electrocatalysts for Water Electrolysis

Aliyev¹,

Guseynova²,

Gurbanova³

et al. 2018

Chemical Problems

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The review paper accumulates the latest information on the analysis of catalyst synthesis for the electrolysis of water in alkaline and partially in acidic media. Literature data on the production of electro-catalysts based on noble, refractory, transition and pure metals, as well as metals doped with molybdenum, phosphorus, and other elements, are presented. Given the different methods of synthesis of electro-catalyst, the advantage of the electrochemical method is emphasized as easy, accessible method enabling to regulate the composition of synthesized electrodes by changing the content of an electrolyte and the conditions of electrolysis, controlling the properties of synthesized materials.

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Electrodeposition of CoMo and CoMoP alloys from the weakly acidic solutions

Cited by 26 publications

References 28 publications

Electrodeposited tungsten-rich Ni-W, Co-W and Fe-W cathodes for efficient hydrogen evolution in alkaline medium

Electrodeposited tungsten-rich Ni-W, Co-W and Fe-W cathodes for efficient hydrogen evolution in alkaline medium

Effect of P codeposition on the structure and microhardness of Co–W coatings electrodeposited from gluconate bath

Electrocatalysts for Water Electrolysis

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