Dynamic impedance studies of oxidation of nickel and glycerol at nickel electrodes.

Date

2019-04-29

Authors

Alikarami, Mohammad

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Abstract

This thesis uses dynamic electrochemical impedance spectroscopy (dEIS) to study how nickel undergoes electrooxidation. An electropolishing step is used to make a clean surface, and then the transformation of nickel to α-Ni(OH)2 is studied, including how a holding potential affects the double layer capacitance, surface structure and charge transfer resistance. Also, NiOOH is grown on the surface by sweeping to more positive potentials, and the activity of NiOOH toward glycerol electrooxidation is studied. It is shown that the free water content decreases on the surface (all or some portions of the surface, or possibly one or two monolayers close to the nickel surface) during the potential hold as determined by the decrease in measured capacitance. Oxidation of glycerol to glyceraldehyde is found to be the main reaction and the reaction mechanism is discussed.

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Keywords

Electrochemistry, fuel cell, Impedance spectroscopy, electrocatalyst, Reaction mechanism, Double layer, Surface science

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