Electrochemical studies of a nickel electrode for the hydrogen evolution reaction (original) (raw)
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Hydrogen evolution on nickel electrode in synthetic tap water – alkaline solution
Fuel and Energy Abstracts, 2011
The effect of tap water contaminants on the kinetics of the hydrogen evolution reaction on a nickel electrode in 1 mol dm−3 KOH was investigated by galvanostatic polarization and electrochemical impedance spectroscopy techniques. It was found that the tap water contaminants lead to an increase in the overpotential of the hydrogen evolution reaction, especially at low temperatures. The combination of electrochemical techniques, as well as physicochemicals such as SEM and EDAX ones, confirmed that the contaminants are specifically adsorbed and blocked the available electrode surface for the reaction. It was concluded that they do not participate in an electrochemical reaction in the potential region where HER occurs. Besides the short term negative impact on the rate of hydrogen evolution, a 55 h test revealed that the overpotential shows a steady increase over time in presence of tap water contaminants, while in absence of these contaminants the overpotential is constant.► Influence of the contaminants in simulated tap water on the hydrogen evolution. ► The mechanism of the reaction is the same as in purified water. ► Contaminants do not take place in the electrochemical reaction. ► Adsorption of anions on the electrode surface leads to increase of the overpotential. ► Gas phase product is the same as the one obtained from purified water.
Kinetics of hydrogen evolution on nickel electrodes
Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 1990
The mechanism and kinetics of the hydrogen evolution reaction (HER) was studied in 1 M N aOH on polycrystalline nickel electrodes using potential step charging, open circuit potential decay and ac impedance techniques. It was shown that the potential step charging technique cannot give correct kinetic results because of the experimental limitations. It was found that the experimental curves may be explained assuming the Volmer-Heyrovsky mechanism. New methods of data analysis for the open circuit potential relaxation and ac impedance are proposed. , process.
Tikrit Journal of Pure Science
This work investigated experimentally and theoretically the I-V output change, the hydrogen production, and the efficiency of Ti and Ni metals as substrates for water electrolysis systems. To make optimization between the candidate electrodes, seven configurations of Ni-Ti, Ti-Ti, and Ti-Ni with three KOH solutions of 10, 20, and 30 % wt (weight KOH gm/weight water gm) as an electrolyte were conducted as a cathode-anode system. The selected electrodes were examined by scanning electron microscopy (SEM) and energy dispersive (EDX) to study their surface morphology and element composition. According to experimental findings, when the cell voltage of 5 V is applied, the hydrogen production from the Ti-Ti (20%KOH) and Ni-Ti (20% and 30% KOH) electrodes reach an optimal value of 6331 cm3, which is significantly higher than the hydrogen production from the other electrodes at the same voltage. The Ni-Ti electrode with a 10% KOH content had the maximum efficiency (72%), and the Ni-Ti elect...
The hydrogen evolution reaction in acid medium on nickel electrodeposited with PW12O3−40
International Journal of Hydrogen Energy, 1989
Al~traet--The hydrogen evolution reaction (h.e.r.) was performed in acid medium at room temperature on nickel electrodeposited cathodes with and without PW~20~0 -(the later electrodes are named here by NiPWj2). An important increase of the exchange current density (io) and a significant decrease of the overvoltage (r/) was obtained for NiPW12. These results were attributed to an activation of the electrodes due to the active species of the reduction of PW~20~-. A model involving these reduced species for the h.e.r, was proposed. These species sensitized the proton reduction for the h.e.r. It has been shown that the exchange current density can effectively be used as an electrochemical parameter for the h.e.r, rate due to the electrocatalytic properties of different interfaces involving these electrodes. The NiPW~2 cathodes showed stable overpotentials during electrolysis of water in acid medium more than 1500h, and were not adversely affected by extended open circuit exposure. They showed high resistance to common electrocatalyst poisons. Scanning electron microscopy showed that this was due to a good resistance of the material to electrochemical decomposition.
Journal of Applied Electrochemistry, 1991
The electrocatalytic activity of nickel black electrodes for the hydrogen evolution reaction (HER) in alkaline solutions was studied. Three types of electrode were obtained through electrodeposition from different plating baths and their electrocatalytic properties were evaluated through slow potentiodynamic sweeps. The apparent and real exchange current densities and the Tafel slopes were calculated and compared to those of Raney nickel electrodes. The importance of the superficial topography on the apparent electrocatalytic characteristics was emphasized and some evidence was given to demonstrate that, when the electrode is previously aged in alkaline solution, the HER is produced on a thin nickel hydroxide overlayer.
The hydrogen evolution reaction in acid medium on nickel electrodeposited with PW12O403−
International Journal of Hydrogen Energy, 1989
Al~traet--The hydrogen evolution reaction (h.e.r.) was performed in acid medium at room temperature on nickel electrodeposited cathodes with and without PW~20~0 -(the later electrodes are named here by NiPWj2). An important increase of the exchange current density (io) and a significant decrease of the overvoltage (r/) was obtained for NiPW12. These results were attributed to an activation of the electrodes due to the active species of the reduction of PW~20~-. A model involving these reduced species for the h.e.r, was proposed. These species sensitized the proton reduction for the h.e.r. It has been shown that the exchange current density can effectively be used as an electrochemical parameter for the h.e.r, rate due to the electrocatalytic properties of different interfaces involving these electrodes. The NiPW~2 cathodes showed stable overpotentials during electrolysis of water in acid medium more than 1500h, and were not adversely affected by extended open circuit exposure. They showed high resistance to common electrocatalyst poisons. Scanning electron microscopy showed that this was due to a good resistance of the material to electrochemical decomposition.
2011
The electrolysis is a technology for production of hydrogen from renewable sources. Modern commercial electrolyzers focus on hydrogen as a chemical, and not as an energy carrier. For the future large-scale production for automotive applications, electrolyzer energy efficiency and the resulting hydrogen quality and cost are important factors that need more attention. The need of ultrapure water in the novel generation of electrolyzers also increases the cost, and therefore hinders their widespread introduction. The use of seawater could prove to be an economically viable solution. The current research investigates the influence of the contaminants in seawater on the hydrogen evolution reaction on Ni electrode in the temperature range of 25-80ºС. The electrochemical kinetic parameters of the reaction-Tafel slope, charge transfer coefficient and exchange current density were evaluated by galvanostatic polarization and electrochemical impedance spectroscopy. Long-term stability test results are also described. All results were compared with the results, obtained in KOH prepared with ultrapure water.