الفهرس 
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Abstract
Electrochemical science and technology can play a vital
role for the indirect storing of extra renewable energy through
converting the electricity into chemical energy. This may
participate in solving the global problem of consuming the
irrecoverable fossil fuels.For instance, water splitting into
hydrogen and oxygen by electrolysis is considered as a hopeful
substitute to electricity storage systems using batteries.
Recently, many intensive studies focused on
constructing high efficient and low cost electrocatalysts mostly
for water splitting reactions: oxygen evolution reaction (OER)
and hydrogen evolution reaction (HER).
This work involves the following:
1. Many cobalt/graphite electrodes were successfully prepared
via chronoamperometry deposition of cobalt from bath
containing Co+2 ions in the absence and presence of
equimolar concentration of citrate ions on graphite
substrate. As graphite is considered as a typical
electrocatalyst support in various energy conversion and
storage devices such as fuel cells, supercapacitors, lithium
ion batteries and water splitting reactions (OER and HER).2. The electrodepostion processe was studied using eQCM
technique, and the morphology of all prepared electrodes
was evidenced using XRD and FESEM techniques.
3. All prepared electrodes were electrochemical charctrised
using cyclic voltammetry (CV), chronopotniometry and
electrochemical impedance spectroscopy (EIS) techniques.
4. The electrochemical behaviour of the prepared electrodes
were investigated as electrocatalyst toward OER in 1M
NaOH solution and the corelation between their surface
structure and electrochemical activity has been extensively
discussed.
5. It has been concluded that the presence of citrate ions in the
electrodeposition bath favors the instantaneous nucleation of
Co speceis deposition rather than the progressive nucleation,
leading to form a more uniform cobalt speceis film on the
graphite substrate. This was confirmed by XRD, FESEM
and EIS techniques. Therefore, the Cobalt/graphite electrode
prepared from citrate bath displayed an enhanced
electrocatalytic activity toward OER.
6. Extra catalytic activity were gained by Co-Cit/G electrode
via successive potentiodynamic polarization in 1M NaOH
solution.
7. Moreover, the chronopotentiometry (potential-time), at
constant current density stability test for 2 h, as recommended in the literature benchmark, showed a
superior stability of Co-Cit/G electrode toward OER in
alkaline medium.