abstract
- © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimNickel and nickel-based nanomaterials are an attractive choice to replace noble metals as electrocatalysts in alkaline direct alcohol fuel cells (ADAFCs) owing to their lower cost and suitable electrocatalytic activity. Among the different synthetic methods available for the production of nanostructured materials, galvanostatic electrodeposition offers a fast and simple means of fabricating active electrodes. Therefore, thin-layers of nickel were electrodeposited onto polycrystalline gold electrodes using constant current pulses from an electrolyte containing 50 mM NiSO4. Combined effects of current density pulse and the presence of sulfate or chloride anions in the supporting electrolyte on the electrocatalytic activity of the deposited nickel nanostructures were studied. The surface concentration of Ni(OH)2 in alkaline medium, evaluated through cyclic voltammetry in 0.5M methanol + 1M KOH, was used as a performance parameter together with the electrocatalytic intensity, EI, defined as the sum of forward and reverse currents densities in methanol electro-oxidation. It was found that highest electrocatalytic activities were obtained when using current density pulses close to 4.0 × 10¿3A cm¿2 in the presence of sulfates, which leads to a strong correlation between the electrocatalytic activity for the oxidation of methanol and the surface concentration of Ni(OH)2, displaying better properties than their chloride counterparts.