The Effect of Temperature and Ethanol on the Deposition of Nickel Hydroxide Films

Abstract

The objective of this work was to determine the effect of the temperature and the ethanol content of the Ni(NQ)2 solution on: (i) the efficiency of electrochemical deposition of nickel hydroxide; and (it) the molecular weight of the deposited film. An electrochemical quartz crystal nanobalance (EQCN) was used to measure the mass of films electrochemically deposited from Ni(NO3)2 solutions and constant current discharges were used to determine the electrochemical capacity of the films. The data indicates that increasing the temperature increases both the efficiency of the deposition reaction and the molecular weight of the deposited film. The increased efficiency at higher temperatures is attributed to a decrease in the concentration of a nickel complex at the surface of the electrode. The lower complex concentration decreases the diffusion rate of this species away from the electrode surface and hence increases the rate at which the complex precipitates from the solution. The increase in the molecular weight at higher temperature is attributed to a combination of increased rate of deposition and an increase in the lattice spacing of the active material. The data also indicate that increasing the ethanol content of the solution had no noticeable effect on the efficiency of deposition, when water was present. In pure ethanol, however, the chemistry of deposition seemed to change considerably. However, increasing the ethanol content of the solution resulted in an increase of the molecular weight of the film. Increase in the molecular weight with an increase in the ethanol content of the solution is due to an increase in the relative percentage of ethanol incorporated in the active material. The data also indicate that the number of electrons in the discharge reaction is approximately 1.4 electrons per nickel atom.

Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes

“…For example, Ni(OH) 2 is most commonly prepared galvanostatically or potentiostatically from an aqueous solution containing nickel nitrate. [159][160][161][162][163][164] Under such circumstances the deposition chemistry involves the direct or indirect reduction of the nitrate ion to either nitrous acid, hydroxylamine or the nitrite ion. 160,171,172 In all cases the hydroxyl ion is generated, resulting in the formation of either a-Ni(OH) 2 or b-Ni(OH) 2 according to eqn (2),…”

Perspectives on Nickel Hydroxide Electrodes Suitable for Rechargeable Batteries: Electrolytic vs. Chemical Synthesis Routes

“…Nickel hydroxide can also be prepared through electrochemical route [ 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 ]. This way of preparation provides some advantages such as purity of the product, elimination of some anions and cations in the system, better control of the process through regulation of current density, and environment friendliness of the process.…”

Electrochemical Deposited Nanoflakes Co(OH)2 Porous Films for Electrochemical Capacitors

“…28 causes to increase the layer distance between crystal lattices, improve the freeness of the ions and the reversibility of Co 2+ /Co 3+ at the charge-discharge processes. 29 Base on the above discussions, we propose that the ethanol plays a crucial role in optimizing supercapacitive performance of the Co(OH) 2 films. Therefore, further electrochemical investigations were focused on the Co(OH) 2 films electrodeposited in water-ethanol solution.…”