Semiconducting and photoelectrochemical characterizations of CuCrO2 powder synthesized by sol-gel method
The delafossite CuCrO2 elaborated by sol gel (SG) route using ethylene glycol as solvent, is p-type semiconductor characterized by a direct band gap of 1.93 eV and activation energy of 0.22 eV. The semi-logarithmic plot gives an exchange current density of 1.8 μA cm−2 in KOH (0.5 M) electrolyte, indicating a good electrochemical stability with a small hysteresis loop and high oxygen over-potential. The structure is highly anisotropic and the electrochemical study is confined in the (a, b) plane with a reversible oxygen intercalation. The capacitance measurement (C−2 - E) exhibits a linear behavior from which a flat band potential of − 0.045 ESCE and a hole density of 8.19 × 1019 cm−3 are determined. The Nyquist diagram shows a small semicircle in the high frequency domain, assigned to the faradic charge transfer, the large semicircle in the medium region is due to grain boundaries while the straight line at low frequencies is attributed to a disparity from pure impedance diffusion.
KeywordsCuCrO2 Semiconductor Sol-gel Photoelectrochemical Electrochemical impedance spectroscopy
The work was financially supported by the Faculty of Chemistry (U.S.T.H.B) (Algiers).
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