Electrochemical reduction of oxygen on nanoparticulate gold electrodeposited on a molecular template

The reduction of oxygen on gold electrodeposited on an organic template has been investigated. The template consisted of reduced 4-nitrophenyl groups attached to glassy carbon (GC) by the electrochemical reduction of the corresponding diazonium compound. The electrode modified by this Au nanostructured film shows electrocatalytic properties for the oxygen reduction reaction (ORR) different from those of bulk Au, GC or GC grafted with 4-nitrophenyl groups. The reduced nitrophenyl film inhibits the O2 reduction reaction. A two-step reduction mechanism with production of hydrogen peroxide in the first step and water in the second was observed in alkaline solutions. The standard heterogeneous rate constants for this two-electron transfer sequential reaction (EE reduction mechanism) have been calculated using non-linear regression analysis (NLR).