Nano metallic particles and their applications for development of direct alkaline fuel cell electrode

Abstract

nano Ni/Graphite electrocatalyst was successfully prepared through electrodeposition of Ni from acidic and feebly acidic aqueous Ni(II) baths. The efficiency of the prepared modified electrodes was investigated through the ethanol electrooxidation response in alkaline medium. A direct proportionality between the amount of the electrodeposited Ni on the graphite surface and the electrocatalytic response was found, where the amount of the deposited Ni was recorded using the Electrochemical Quartz Crystal Microbalance eQCM. Hence, the electrode deposited from the feebly acidic bath showed a higher electrocatalytic response than its analogous deposited from the acidic bath. Moreover, the Study of the Ni electrodeposited from feebly acidic bath surface morphology indicated that the electrodeposited Ni particles exist in the nano-scale dimensions. Various electrochemical experiments were conducted to explain the influence of pH, nickel ions concentration, electrode orientation and electrode preparation parameter on the efficiency of the deposition process. The experimental results have pointed out that the electrodeposition of nickel greatly depends on the pH of the deposition medium and the surface structure rather than nickel ion concentration. However, Although The amount of the deposited Ni was below the detection limit of the XRD yet the eQCM technique was used to detect the crystalline phases of nickel as α- 81 | P a g e Ni(OH)2 / γ-NiOOH and β-Ni(OH)2 / β-NiOOH and their in-situ inter-transformations during the potentiodynamic polarization.