In the current work, we have developed a new composite catalyst for methanol oxidation based on Ni and/or NiO incorporated in activated carbon (AC) derived from agricultural wastes (Rice straw). The new electrocatalysts based on nickel-activated carbon (Ni/AC) and nickel oxide-activated carbon (NiO/AC) composites were prepared by electroless plating technique. Physico-chemical characteristics of the composites such as structure, composition and morphology were studied by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and particle size analyzer. The electrochemical activity of the prepared composites towards methanol electrooxidation reaction (MOR) has been evaluated under alkaline conditions by cyclic voltammetry, linear sweep voltammetry, and chronoamperometry. Among the examined electrodes, the electrochemical performance of NiO/AC preceded either Ni/ AC or Ni free AC and showed better stability. The dispersion of different forms of Ni in activated carbon in case of NiO/AC electrode is predicted to give rise to the increase in electrocatalytic activity in the potential range under study and makes it more resistant to poisoning by the byproduct of methanol oxidation. The effect of changing methanol concentrations and scan rates on the electrochemical characteristics of the modified electrode was studied and it was found that the diffusion process is controlled by methanol rather than OH− ions.

    Abstract
    1 Introduction
    2 Experimental
        2.1 Preparation of AC derived from rice straw
        2.2 Preparation of NiAC and NiOAC
        2.3 Characterization of prepared AC, NiAC and NiOAC
        2.4 Electrochemical measurements
    3 Results and discussions
        3.1 Characterization of AC, NiAC and NiOAC
        3.2 Electrochemical behavior of the composites
    4 Conclusion
    References

• Ahlam M. Fathi(Physical Chemistry Department, National Research Centre)
• Hala T. Handal(Inorganic Chemistry Department, National Research Centre)
• Ahmed A. El‑Kady(Food Toxicology and Contaminants Department, National Research Centre)