الفهرس 
Introduction and Literature surveyOnly 14 pages are availabe for public view
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Abstract
The present study includes the fabrication of carbon xerogel (CX) samples via sol–gel polycondensation of resorcinol and formaldehyde with various operating pyrolysis temperatures, 600, 750, 900 and 1100 °C. Analyzing the CX samples reveal that the thermal treatment temperature affects the surface texture, functional groups, and consequently the final performance toward oxygen evolution reaction (OER) and oxygen reduction reactions (ORR). The specific surface area (SBET) parallel with the microporous character of the studied samples increases gradually by increasing the pyrolysis temperature to 900 °C and subsequently decreases at higher temperatures. The prepared CX samples were DROP casted over bare graphite electrode (G) surface and tested as electrocatalysts on their own for both OER, may be for the first time, and ORR. Our obtained results demonstrate that the more efficient electrode among studied ones was that prepared at 900 oC pyrolysis temperature (CX-9/G). Moreover, the CX-9/G electrode exhibits an overpotential required to achieve a current density of 10 mA. cm− 2 (ηt=0) value of 0.38 V for OER, and E onset @ -0.1 mA.cm-2 of 0.93 V vs RHE with half-wave potential (E ½) of 0.64 V vs RHE for ORR. Also, CX-9/G shows signs of excellent stability as a low-cost material when compared with the other published works.
Part (B):
Different Nickel/carbon xerogel composites with various Ni mass ratios, Ni-x/CX, are prepared. Their surface characterization reveals that introducing Ni into the CX network increases the specific surface area with simultaneous development of the pores from the mesoporous to the microporous range. XRD study indicates the formation of a mixture of nano particles of cubic bunsenite NiO and metallic Ni phases. XRD, SEM images and FTIR spectra confirm the presence of topmost Ni/NiO particles covering the CX network at relatively high percentage of Ni doping. The prepared Ni-x/CX are suspended in Nafion solution and drop-casted on supporting surfaces and their electrochemical activity towards ethanol oxidation reaction (EOR) are tested by cyclic voltammetry (CV) as anodes in direct alkaline ethanol fuel cell in 1 M NaOH + 1 M Ethanol solutions. Au, Pt, glassy carbon and graphite substrates were tested. The optimum electrode is made of 6% weight of Ni doped in CX matrix and drop-casted on a graphite surface, Ni-6/CX/G. This electrode has an oxidation peak current density value of 833 A.g-1 (or 5925 A.g_Ni^(-1)) with considerable stability. Rotating Ring Disk Electrode (RRDE) study emphasizes the delay of the OER to potentials more anodic than the EOR peak potential.
Part (C):
The linear sweep voltammetry (LSV) study shows that α-Ni(OH)2 could be obtained chronoamperometricaly over bare graphite surface in potential range starts from -0.5 reaching its maximum amount at -0.9 V then starts to decrease at more cathodic potentials. However, when the time of deposition exceeds 150 s, the β-Ni(OH)2 is more predominate. Ni(OH)2/G(opt) electrode is chronoamperometricaly deposited on G electrode from 0.01 M NiCl2 solution with an optimum potential of −0.9 V for 150 s. This optimum electrode yields an ethanol oxidation peak with a maximum current density of 325.35 mA.cm−2. Furthermore, Ni(OH)2/G(opt) electrode displays remarkable activity and stability for OER in 1 M NaOH. The overpotential required to achieve 10 mA.cm−2 is 0.37 V; whereas, after 24 h, (ηt=24h) is 0.39 V. When compared to the previously published work. The above-described values represent notable results for our simple and straightforward fabrication method for such an effective EOR and OER electrocatalysts using low-cost materials.