Electrochemical codeposition of nickel oxide and polyaniline

Nickel oxide (NiO _x) and polyaniline (PAni) were electrocodeposited from NiSO ₄ and aniline through cyclic voltammetric scans to afford PAni-NiO _x composite film at controlled pH environment. The electrochemical activities of the film were investigated by cyclic voltammetry in 0.1 M NaOH and 0.1 M H ₂SO ₄, respectively. Typical redox couples of PAni in 0.1 M H ₂SO ₄ appeared at approximately 0.2 and 0.4 V vs. saturated calomel electrode (SCE); Ni(II)/Ni(III) redox couple was observed at approximately 0.4 V vs. SCE in 0.1 M NaOH. The morphologies and elemental components of the films were inspected by scanning electron microscopy and energy dispersive X-ray diffraction. The stability of nickel oxide in the films was found to be enhanced against acidic environments. Electrochemical catalytic behavior of NiO _x within the composite film was conserved and demonstrated by catalytic oxidation of methanol and ethanol.