Novel Ni foam based nickel oxalate derived porous NiO nanostructures as highly efficient electrodes for the electrooxidation of methanol/ethanol and urea

In this paper, porous NiO with three-dimensional (3D) nanostructures are prepared by a chemical bath deposition (CBD) process in oxalic acid solution at a fixed temperature using Ni foam (NF) as the substrate and Ni source, and followed by an electrochemical activation treatment in an alkaline medium. The special 3D porous structure of the as-prepared NF based NiO (NiO/NF) electrode is benefit for the diffusion of fuels (CH3OH/C2H5OH and urea) during the electrochemical reaction. Besides, the obtained NiO may combine with the remained nickel oxalate (NiC2O4) to further enhance the catalytic performance due to its synergistic effect. At 0.60 V, the electrooxidation current density reached 257 mA cm−2 in 1.0 mol dm−3 NaOH and 0.40 mol dm−3 CH3OH, and a high performance of 120 mA cm−2 was achieved in 1.0 mol dm−3 NaOH and 0.10 mol dm−3 C2H5OH. The oxidation current density reached 222 mA cm−2 in 0.1 mol dm−3 urea with the NaOH concentration of 8.0 mol dm−3 at around 0.48 V. The facile preparation method, high electrocatalytic activity, low cost and various applications make the NiO/NF be a promising electrode material. •NiO porous nanostructures are prepared by the electrochemical activation of NiC2O4.•NiO/NF owns super electrocatalytic activity towards CH3OH/C2H5OH and urea oxidation.•Remaining NiC2O4 may combine with NiO to form a composite to improve the activity.