This work reported the electrochemical and photoelectrochemical (PEC) properties of a new photoelectrode based on hematite Co-Fe2O3@NiO, a photoactive semiconductor, was prepared using a process involving a combination of the co-precipitation and microwave-assisted synthesis of Fe2O3, Co-Fe2O3 and Co-Fe2O3@NiO, respectively. The obtained products were characterized by X-Ray powder Diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive X-ray analysis (EDX), Ultraviolet–Visible (UV–vis) analysis, Fourier Transform Infrared spectroscopy (FT-IR). X-ray diffraction (XRD) pattern of the sample determined the crystal structure of α-Fe2O3 nanoparticles. The SEM image shows spherical nanoparticles. FTIR spectrospy spectrum confirmed the phase purity and chemical bond for the sample. Optical studies show a variation of band gap from 2.118 to 2.07 eV. The electrochemical and photoelectrochemical (PEC) performance of the films were examined by cyclic voltammetry, linear sweep voltammetry and chronoamperometry. The electrochemical oxidation of water achieved by Cobalt-doped Fe2O3@ GCE modified electrode exhibited the current density of 21 mA/g at 0.5 V vs. SCE for 5 at% of Co and reveals enhanced specific capacitance of 352.11 F/g. The catalytic performance of urea oxidation was measured by cyclic voltammetry on Co-Fe2O3@NiO nanoparticles modified glassy carbon electrode (GCE) in alkaline medium. The electrode Co-Fe2O3@NiO without annealing showed a peak current density of 1.59 mA/cm2 at 0.1 M urea in 1.0 M NaOH, which was 3.6 fold higher than that of Co-Fe2O3@NiO with annealing. In another part, this work reported the photoelectrochemical (PEC) properties of photoanode prepared by spin coating. The highest photocurrent 0.042 mA/cm2 at 0.5 V Vs SCE was obtained for 5% Co-Fe2O3@NiO while the photocatalytic oxidation of urea.

    Abstract
    1 Introduction
    2 Experimental
        2.1 Materials
        2.2 Synthesis of pure, Co-doped α-Fe2O3 and Co-Fe2O3@NiO nanoparticles
        2.3 Preparation of α-Fe2O3, Co-Fe2O3 and Co-Fe2O3@NiO nanoparticles modified GC electrode
        2.4 Preparation of the α-Fe2O3, Co-Fe2O3 and Co-Fe2O3NiO films
        2.5 Characterization
        2.6 Electrochemical and photoelectrochemical measurements
    3 Result and discussion
        3.1 Structural analysis
        3.2 SEM observationsEDX
        3.3 Fourier Transform Infra-Red (FT-IR) spectroscopy
        3.4 Optical analysis
        3.5 Electrochemical measurement
        3.6 Electrocatalytic oxidation of urea
        3.7 Photoelectrochemical measurement
    4 Conclusion
    Acknowledgements 
    References

• Assia Karrab(Matériaux Et Environnement UREME (UR17ES45))
• Remi Bensimon(CNRS, Univ Paris Est Creteil, ICMPE)
• Diane Muller(CNRS, Univ Paris Est Creteil, ICMPE)
• Stéphane Bastide(CNRS, Univ Paris Est Creteil, ICMPE)
• Christine Cachet‑Vivier(CNRS, Univ Paris Est Creteil, ICMPE)
• Salah Ammar(Matériaux Et Environnement UREME (UR17ES45))