Activating bulk nickel foam for the electrochemical oxidization of ethanol by anchoring MnO2@Au nanorods

Abstract

Direct ethanol fuel cells (DEFCs) using biomass-derived fuel is a promising sustainable energy conversion system for enabling a carbon-neutral society. However, such an imperative task is impeded by the stability-deficiency of powdery catalysts and the activity-weakness of bulk non-noble metal catalyst for the ethanol oxidation reaction (EOR). In the present study, a surface-modification strategy for activating the EOR ability of bulk non-noble nickel foam is demonstrated. The anchored MnO₂@Au nanorods on nickel foam induced strong interfacial interactions between the nickel foam and MnO₂ nanorods as well as Au nanoparticles, providing not only more reactive sites but also enhanced ion transportation. Resultantly, the functionalities of the bulk nickel foam as both a current collector and catalyst were integrated into one alliance. Benefiting from such a hieratical microstructure and well-defined composition design, the MnO₂@Au-modified bulk nickel foam presented 31% increase in steady current density at 1.8 V vs. RHE, 28% decrease in the Tafel slope, and 40% more reactive sites compared with the bare nickel foam, outperforming most nickel-based candidates. Such a special surface-structure reconstruction embraced the current-collector functionality together with the catalytic functionality, which mitigates the stability-weakness puzzle for powdery catalysts and activity-deficiency for bulk nickel current collectors at the same time, providing new insights for the design of electrodes for DEFCs.