Electrochemical intercalation of O2− in CuAlO2 single crystal and photoelectrochemical properties

• Published in: Journal of solid state electrochemistry 2010-07, Vol.14 (7), p.1333-1338
• Main Authors: Brahimi, Razika, Trari, Mohamed, Bouguelia, Aïssa, Bessekhouad, Yassine
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Electrochemistry; Energy Storage; Original Paper; Physical Chemistry
• ISSN: 1432-8488; 1433-0768
• DOI: 10.1007/s10008-009-0935-x

The delafossite CuAlO 2 single crystal, prepared by the flux method, is a low mobility p-type semiconductor with a hole mobility of 1.2 × 10 −5  cm −2  V −1  s −1 . The chronoamperometry showed an electrochemical O 2− insertion with a diffusion coefficient D 303K of 3.3 × 10 −18  cm 2  s −1 . The thermal variation of D in the range 293–353 K gave an enthalpy of diffusion (Δ H ) of 44.7 kJ mol −1 . CuAlO 2 is photoactive, and the Mott–Schottky plot indicates a flat band potential of +0.42 V vs saturated calomel electrode and a holes density ( N A ) of 10 16  cm −3 . The photocurrent spectra have been analyzed by using the Gartner model from which the absorption coefficients and diffusion lengths were determined. An optical transition at 1.66 eV, indirectly allowed, has been obtained. The spectral photoresponse provides a high absorption at 480 nm. The low quantum yield ( η ) is attributed to a small depletion length (440 nm) and a hole diffusion width (271 nm) compared to a very large penetration depth (12 µm).