Decoupling interfacial kinetics in ternary ZnO-CuOx-NiO electrocatalysts for ethanol oxidation via distribution of relaxation times analysis

Direct ethanol fuel cells (DEFCs) are emerging as viable alternatives for sustainable power generation, yet their deployment remains constrained by the reliance on noble-metal electrocatalysts. Herein, a ZnO-CuO x -NiO ternary composite was synthesized via a modified multistep polyol method, using a water/ethylene glycol medium. Electrochemical performance was systematically evaluated in alkaline media using cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS), both in the absence and presence of ethanol in 0.5 mol L −1 NaOH. The composite exhibits well-defined redox features associated with the Cu and Ni oxyhydroxide, accompanied by high peak current densities. Upon addition of 0.5 mol L −1 ethanol, the electrocatalytic response was markedly enhanced, reaching a peak current density of 32 mA cm −2 at 1.65 V vs RHE. Moreover, the distribution of relaxation time (DRT) analysis reveals accelerated charge-transfer kinetics in the aged sample compared to the untreated counterpart.