Performance of MOF-Derived Spinel Type NixCo3-xO4-y Nanocages in Efficient Methanol Electro-Oxidation

The 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 a methanol oxidation reaction (MOR) current of approximately 200 Ag-1 at 0.55 V versus Hg-HgOx which is around 12 times higher than that from Co3O4. Improve(d) activity for the catalyst is ascribed to its higher number of catalytic active sites and non-stoichiometry in the composition. The improved charge-transfer kinetics for the MOR is evident from the electrochemical impedance measurements, where a lower charge-transfer resistance is observed for NixCo3-xO4-y nanocages 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.