Transition metal oxides synthesized by self-sustaining combustion method as an accelerator to desorb produced intermediates during ethanol oxidation

Abstract

One of the leading parts of electrocatalyst design is selecting a proper support material. On the one hand, metal oxides like Cerium (IV) oxide (CeO2) and Nickel (II) oxide (NiO) enhance the concentration of adsorbed Hydroxyl (OHads) species and considerably decrease the onset potential in the electrochemical oxidation of ethanol. On the other hand, these oxides have excellent oxygen storage capacity due to altering their Nickel (III)/Nickel (II) (Ni3+/Ni2+) and Cerium (IV)/Cerium (III) (Ce4+/Ce3+) redox pair. So, CeO2 and NiO were synthesized with a porous structure as one part of the support materials. In addition, Carbon-based materials have been considered notable support components for ethanol oxidation. So, graphene oxide (GO) was synthesized as the second part of support materials because of the anti-poisoning effect and excellent electrical conductivity. The electrochemical active surface area of Pd loaded on NiO-CeO2 two phases’ porous oxides and GO was highly improved by synergic effects of CeO2, NiO and GO. In evaluating ethanol oxidation, the anodic current and long-term stability of the Pd-NiO-CeO2-GO electrocatalyst were much higher than other modified electrocatalysts. Finally, to estimate the ethanol adsorption pattern on the Pd-NiO-CeO2-GO surface electrocatalyst, the experimental data were fitted to notable isotherms; which had the better fitting with Frumkin isotherm.