Constructing Ni(OH)₂ nanosheets on a nickel foam electrode for efficient electrocatalytic ethanol oxidation

The main bottleneck faced by traditional hydrogen production technology through water electrolysis lies in the high energy consumption of the anodic oxygen evolution reaction (OER). Combining the thermodynamically favorable ethanol oxidation reaction (EOR) with the hydrogen evolution reaction provides a promising route to reduce the energy consumption of hydrogen production and generate high value-added products. In this study, a facile method was developed for nickel oxyhydroxide (NiOOH) fabrication. Diverse carboxylic acids were utilized to adjust the surface structure of nickel foam. A self-supporting nickel foam electrode with Ni(OH)₂ nanosheets (FU-NF) was obtained by reacting fumaric acid and nickel foam in DMF through solvothermal treatment. The interconnected Ni(OH)₂ nanosheets form a uniform 3D skeleton network architecture that exposes abundant active sites toward the EOR. Electrochemical studies in the EOR showed that the Ni(OH)₂ nanosheets were oxidized into a higher valence state to form NiOOH species, which is evidenced by <i>in situ</i> Raman spectroscopy. The reconstructed NiOOH served as an active species, thereby enhancing the EOR electrocatalytic activity of FU-NF. The FU-NF electrode exhibited remarkable EOR catalytic activity with current densities of 10 and 100 mA cm^-2 at 1.314 and 1.353 V_RHE, respectively, and achieved a high faradaic efficiency of 99.84% and maintained outstanding stability for over 100 h. This work provides a new strategy to prepare Ni-based catalysts to convert ethanol into high value-added products.