Hardness and structure of nickel electrodeposited from its sulphate and acetate salts in a 5mol.%N-methylformamide-water mixture

Sultan, S.; Tikoo, P. K.

doi:10.1016/0376-4583(84)90109-2

Cited by 5 publications

(3 citation statements)

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“…18,19 Organic solvents, pure as well as in a mixture, are increasingly used in electrodeposition processes. 20,21 The use of organic solvents as additives in the electrolytes results in changing the mechanism of the electrodeposition process, which makes it possible to develop films with greater thickness, e.g., 200-500 µm. In this paper, we report on the fabrication of nanostructured thick films of bismuth telluride by an electrodeposition technique.…”

Section: Introductionmentioning

confidence: 99%

“…Various organic additives in relatively small addition amounts have been shown to have large effects on the physical properties of electrodeposited films, such as brightness, smoothness, hardness, and ductility. , Organic solvents, pure as well as in a mixture, are increasingly used in electrodeposition processes. , The use of organic solvents as additives in the electrolytes results in changing the mechanism of the electrodeposition process, which makes it possible to develop films with greater thickness, e.g., 200−500 μm. In this paper, we report on the fabrication of nanostructured thick films of bismuth telluride by an electrodeposition technique.…”

Section: Introductionmentioning

confidence: 99%

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Fabrication of Nanostructured Thermoelectric Bismuth Telluride Thick Films by Electrochemical Deposition

et al. 2006

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Bismuth telluride (Bi 2 Te 3 )-based solid solutions are state-of-the-art thermoelectric (TE) materials for cooling applications at room temperature with a high figure of merit ZT. Nanostructured TE bismuth telluride thick films have been fabricated by electrodeposition from a solution containing bismuth nitrate and tellurium dioxide in 1 M nitric acid onto gold-sputtered aluminum substrates. A conventional threeelectrode cell was used with a platinum sheet as the counter electrode and a saturated calomel electrode (SCE) as the reference electrode. Ethylene glycol (EG) was added to the electrolyte in order to increase the thickness of the deposited films, and its effect on the structure, morphology, and compositional stoichiometry of the deposited film was investigated. SEM and XRD were used for structural and compositional characterization. Bismuth telluride films with thicknesses of ca. 350 µm, a stoichiometric composition of Bi 2 Te 3 , and a hexagonal crystal structure were obtained. A microprobe technique was used to measure the lateral Seebeck coefficient in several samples. The free-standing films were shown to be of high homogeneity, where the abundance distribution of the Seebeck coefficient showed a half width of less than 1 µV K -1 and a high electrical conductivity of around 450 S cm -1 at room temperature.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fabrication of Nanostructured Thermoelectric Bismuth Telluride Thick Films by Electrochemical Deposition

et al. 2006

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“…The reduction of hydronium ions at the catholyte leads to the codeposition of Ni(OH) 2 along with Ni. The origin of Ni(OH) 2 generation has been explained earlier (25,29,31). Compared with direct current deposition (DP), cycling potentiostatic and galvanostatic pulses in PP changes the morphology of nickel deposits from pure nickel to layered Ni/colloidal Ni(OH) 2 deposits on the graphite substrate to a greater extent (Fig.…”

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Electrocatalytic hydrogen evolution reaction activity comparable to platinum exhibited by the Ni/Ni(OH) ₂ /graphite electrode

Chhetri

Sultan

Rao

2017

Proc. Natl. Acad. Sci. U.S.A.

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Electrochemical dual-pulse plating with sequential galvanostatic and potentiostatic pulses has been used to fabricate an electrocatalytically active Ni/Ni(OH) 2 /graphite electrode. This electrode design strategy to generate the Ni/Ni(OH) 2 interface on graphite from Ni deposits is promising for electrochemical applications and has been used by us for hydrogen generation. The synergetic effect of nickel, colloidal nickel hydroxide islands, and the enhanced surface area of the graphite substrate facilitating HO-H cleavage followed by H(ad) recombination, results in the high current density [200 mA/cm 2 at an overpotential of 0.3 V comparable to platinum (0.44 V)]. The easy method of fabrication of the electrode, which is also inexpensive, prompts us to explore its use in fabrication of solar-driven electrolysis.hydrogen evolution reaction | dual-pulse plating | nickel/nickel hydroxide interface | graphite rod electrode T o render electrochemical generation of H 2 from water ecofriendly, we could use electricity from solar photovoltaic devices. A major limitation would still be the use of Pt as the catalyst. In the last few years, there has been great interest in replacing Pt by inexpensive, readily available catalysts. Several catalysts have been studied in recent times for the electrochemical hydrogen evolution reaction (HER) including transition metal-based heterostructures (1-6) and certain metal-free catalysts (7-11). Of these, Ni-based catalysts such as Ni 2 P (12, 13), NiFeP (14), NiFe layered double hydroxide (15-17), and Ni/ NiO/carbon nanotube (18) seem to be more promising for water splitting. It has been shown recently that activation of a Nicarbon-based catalyst through the application of an electrochemical potential results in HER activity comparable to Pt in acidic medium (6). We have been investigating the use of Ni along with Ni(OH) 2 as a potential catalyst for the purpose, since Ni(OH) 2 clusters with Pt and other transition metals (19-23) generally exhibit good HER activity and Ni itself is only next to Pt in activity. With this purpose, we have used the dualpulse-plating (PP) method (24) to generate the Ni/Ni(OH) 2 interface embedded in graphene sheets on a graphite electrode. Amazingly, the Ni/Ni(OH) 2 /graphite electrode prepared by us gives a current density of ∼200 mA/cm 2 [at −0.30 V vs. reversible hydrogen electrode (RHE)] and an overpotential of ∼190 mV required to sustain a current density of 20 mA/cm 2 over long periods. For a current density of 200 mA/cm 2 , this electrode beats the activity of the Pt wire by a factor of ∼1.5 in terms of the overpotential.The outstanding performance of the Ni/Ni(OH) 2 /graphite electrode is due to the dual-PP method adopted by us to give rise to colloidal hydroxide inclusions in the electrodeposits (25-30) (Methods). While fabricating the Ni/Ni(OH) 2 interface, the galvanostatic pulses shift the cathodic potential in the negative direction to such an extent that the ensuing water splitting yielding hydrogen is followed by the simultaneous incorporati...

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Utilization of microhardness impressions to determine physical state of nickel electrodeposits

Sultan¹

2007

Metal Finishing

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Hardness and structure of nickel electrodeposited from its sulphate and acetate salts in a 5mol.%N-methylformamide-water mixture

Cited by 5 publications

References 2 publications

Fabrication of Nanostructured Thermoelectric Bismuth Telluride Thick Films by Electrochemical Deposition

Fabrication of Nanostructured Thermoelectric Bismuth Telluride Thick Films by Electrochemical Deposition

Electrocatalytic hydrogen evolution reaction activity comparable to platinum exhibited by the Ni/Ni(OH) ₂ /graphite electrode

Utilization of microhardness impressions to determine physical state of nickel electrodeposits

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Hardness and structure of nickel electrodeposited from its sulphate and acetate salts in a 5mol.%N-methylformamide-water mixture

Cited by 5 publications

References 2 publications

Fabrication of Nanostructured Thermoelectric Bismuth Telluride Thick Films by Electrochemical Deposition

Fabrication of Nanostructured Thermoelectric Bismuth Telluride Thick Films by Electrochemical Deposition

Electrocatalytic hydrogen evolution reaction activity comparable to platinum exhibited by the Ni/Ni(OH) 2 /graphite electrode

Utilization of microhardness impressions to determine physical state of nickel electrodeposits

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Electrocatalytic hydrogen evolution reaction activity comparable to platinum exhibited by the Ni/Ni(OH) ₂ /graphite electrode