Ni sulfide nano-sheets as an efficient standalone electrode in direct ethanol fuel cells

Direct alcoholic fuel cells such as DEFCs “direct ethanol fuel cells” have a high energy density and can potentially replace secondary batteries in portable applications. Two main challenges of the DEFCs are the low efficiency and the precious/expensive Pt-based electrodes. In this study, a standalone nickel sulfide electrode was grown on the surface of nickel foam via hydrothermal method followed by hydrothermal ion exchange. The prepared electrodes have a highly porous nanosheet structure and demonstrated high ethanol oxidation activity. The electrode showed high stability and excellent mass transfer properties with a constant generation of current density of 100 mAcm−2 at 0.5 V, two times that of the Ni-layered double hydroxide and ten times that of nickel foam. The superior activity was due to the enhanced charge transfer of the nickel sulfide (confirmed by EIS (electrochemical impedance spectroscopy)) and the improved mass transfer of the highly porous nanosheet structure.