Photo electrochemical properties of co-doped ZnO nanoparticles. Application to the degradation of OII under solar light

The Zn1-xCoxO system (x = 0 and 0.1) were prepared by nitrate route. The diffractogram are indexed in the hexagonal Wurtzite structure. The scanning electron microscopy exhibits well-developed nano-particles homogeneously dispersed. The electrical conductivity (sigma(300K) = 1.43 x 10(-4) and 2.08 x 10(-4) Omega(-1) m(-1) for x = 0 and 0.1 resp.) increases the photo oxidation of Orange II (OII) upon sunlight through the extension of the depletion width. At pH similar to 7, the capacitance(-2) - potential (C-sc(-2) - E) graph indicated n type conduction due to vacancies with a flat band potentials (E-fb) equal to -0.55 and -0.57 V-SCE respectively for x = 0 and 0.1. The semicircle in the complex impedance, measured between 1 mHz and 10(5) Hz, is due mainly to the bulk material with a depletion, assigned to a deviation from a capacitive character. The improved photoactivity of Zn1-xCoxO for the Orange II degradation under sunlight demonstrates the electrical energy consumption. The elaborated oxides remain stable after five cycles. Zn1-xCoxO was found to remove OII (10 ppm), efficiently on Zn0.9Co0.1O under sunlight with an abatement of 80 %.