Abstract
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
2
SO
4
, respectively. Typical redox couples of PAni in 0.1 M H
2
SO
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.