Electrocatalytic Activities of Nano-Sized Spinel-Type CuxCo3-xO4 (0≤ x ≤1) for Methanol Oxidation in Alkaline Solutions

Nano-sized spinel-type CuxCo3-xO4 (x = 0, 0.3, and 1.0) have been prepared by the hydroxide-carbonate co-precipitation method at 3500C and investigated their electrocatalytic activities towards methanol oxidation in alkaline solutions at 250C using cyclic voltammetry, chronoamperometry, impedance spectroscopy and anodic Tafel polarization techniques. The reaction indicated a Tafel slope of ~ 2.303RT/F and order w.r. to [OH-] and [CH3OH] ~ 1 and ~ 0.5, respectively. The rate of electro-oxidation of methanol was found to increase with increasing substitution of Cu for Co in the oxide matrix. The apparent methanol oxidation current densities found on these oxide anodes at E = 0.5V versus Hg / HgO in a mixture of 1M KOH and 1M CH3OH were ~26, ~39 and ~45 mAcm-2mg-1 for x = 0, x = 0.3 and x = 1.0, respectively. The oxide electrodes did not show any surface poisoning by methanol oxidation intermediates / products during chronoamperometry experiments. Based on results, a suitable mechanism for the oxidation reaction has been suggested.