Performance of MOF derived spinel type NixCo3-xO4-y nanocages in efficient methanol electro-oxidation

Present study reports electrocatalytic activity towards methanol oxidation of mesoporous NixCo3-xO4-y fabricated through a Metal-Organic Framework (MOF) template route. MOF derived NixCo3-xO4-y nanocages exhibit methanol oxidation reaction (MOR) current of ~200 Ag-1 at 0.55 V vs Hg-HgO which is ~12 times higher than that from Co3O4. Improved activity for the catalyst is ascribed to its higher number of catalytic active sites and nonstoichiometry in the composition. The improved charge transfer kinetics for MOR reaction is evident from the electrochemical impedance measurements where a lower charge transfer resistance is observed for NixCo3-xO4-y nanocage and the trend is consistent with the MOR results. The potential dependent impedance measurements suggest that direct electrochemical MOR is facilitated through a surface intermediate, where the surface intermediates (CH3OH or CO) are adsorbed on low coordinated Ni and Co sites respectively.