الفهرس 
ElectrocatalysisOnly 14 pages are availabe for public view
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Abstract
Graphite is a typical electrocatalyst support in alkaline energy
conversion and storage devices such as fuel cells, supercapacitors
and lithium ion batteries. The electrochemical behaviour of
graphite electrode in 0.5M NaOH was studied to elucidate its
surface structure/electrochemical activity relationship. Graphite
cyclic voltammograms were characterized by an anodic shoulder
AI and a cathodic peak CI in addition to the oxygen reduction
reaction plateaus, PI and PII. AI and CI were attributed to
oxidation and reduction of some graphite surface function groups,
respectively. Rotating ring disk electrode (RRDE) study revealed
two different oxygen types assigned as inner and outer oxygen.
The inner oxygen was reduced via the more efficient 4-electron
pathway while the outer oxygen proceeded with a lower efficient
2-electron pathway. The calculated percentages of the 4-electron
pathway were ranged from 70% to 90%. A full mechanism over the studied potential window was suggested through the
combination between the voltammetric and FT-IR results.
Part (II)
Nano nickel modified graphite (Ni/G) electrode was prepared
through the electrodeposition of Ni on graphite support as a
typical anode material for Direct Alcohol Fuel Cells. The
deposited nano nickel was found to undergo the instantaneous
nucleation at the initial stages and converted to the progressive
nucleation at the later stages of electrodeposition. The
morphology of the electrodeposited nano nickel was characterized
and found to be a nano spherulite like structure. The
electrochemical behaviour of Ni/G electrode was studied in 0.5M
NaOH without and with 1M EtOH. However, the behaviour of the
Ni/G electrode was found to be a complex combination between
the electrochemical behaviour of bare graphite (BG) and pure
bulk Ni electrodes. The cyclic voltammetry feature of Ni/G
electrode involved three anodic peaks in the forward span A1, A2
and A3 similar to bulk Ni electrode. On the reverse span reactivation peak RA3 was also appeared. Moreover, a single step
plateau (PIII) was observed in the oxygen reduction reaction
potential range. In addition, one cathodic peak CNi/G was observed
and attributed to overlapping between C1 of the BG and C2-C3 of
bulk Ni electrode. The CNi/G cathodic peak is maintained almost
constant while PIII enhanced on repetitive cycling with increasing
vertex potential. However, it was lowered by repetitive cycling
with fixing the potential window limits. The effect of the
electrodeposition bath parameters was examined towards the
electro-catalytic activity of the modified electrode for ethanol
electrooxidation. where the maximum obtained stable response
value was 162mA/cm 2. Very interesting discrepancies in the
cyclovoltammetric behaviours of the Ni/G electrode appeared
when we its surface was laterally faced with the electrolyte since
it give a higher and more stable response than that produced by
downward faced electrode surface. Although XRD was unable to
detect the deposited nano Ni on the graphite surface, EQCM
combined CV was used as an effective tool to detect the nature and phases of Ni on the surface of Ni/G electrode. The mass
profile of the electrodeposited layer revealed the formation of
mixed type of α,β and γ Ni(OH)2/NiOOH layer. The % of the β
components increase during the EtOH oxidation and also increase
as the number of successive cycles increase.