Electrooxidation of ethylene glycol coupled with hydrogen production on porous NiO/Ni@NF nanosheet electrocatalysts†

Abstract

Electrooxidation of small organic compounds plays a crucial role in clean and efficient energy. This technology has the potential to transform waste materials into useful fuels and chemicals for renewable energy applications. Recently, ethylene glycol (EG) has gained considerable attention due to its high energy density, making it a great fuel for direct alcohol fuel cells. EG electrooxidation has attracted significant interest as an alternative hydrogen energy source to water splitting due to its sustainability and cost effectiveness. In this study, porous NiO/Ni_x@NF nanostructured catalysts were synthesized to enhance alkaline EG electrooxidation reactions. Electrodeposition was employed to grow these NiO/Ni_x structures on nickel foam (NF). The electrochemical characterization results indicate that the porous NiO/Ni_x@NF catalyst exhibits an onset potential of 1.3 V vs. RHE for the electrochemical oxidation of EG in a 1.0 M KOH solution. Additionally, this electrocatalyst has a maximum electrocatalytic activity of 121.6 mA cm⁻², 4.5 times greater than that of the bare Ni@NF catalyst (27.2 mA cm⁻²). Moreover, Ni/NiO@NF demonstrated excellent electrocatalytic performance for both cathodic and anodic reactions, including EG electrooxidation and hydrogen evolution reaction (HER). The developed NiO/Ni_x@NF materials catalyzed EG electrolysis with a faradaic efficiency of 45.5%, demonstrating their ability to facilitate electrolysis. The electrocatalytic activity of NiO/Ni_x@NF porous catalyst toward EG is adequate and stable. Therefore, it appears to be a promising option for using EG in fuel cells.