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

Abstract

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 (σ300K = 1.43 × 10−4 and 2.08 × 10-4 Ω−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 ∼ 7, the capacitance-2 - potential (Csc-2 - E) graph indicated n type conduction due to vacancies with a flat band potentials (Efb) equal to −0.55 and −0.57 VSCE respectively for x = 0 and 0.1. The semicircle in the complex impedance, measured between 1 mHz and 105 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 %.