Optical properties of SxZnO and their effect toward the photoacativity

Abstract

SxZnO has been prepared at different S-content using a simple Sol-Gel method at 450 °C. The structural analysis showed the formation of pure wurtzite phase without secondary impurities. According to XPS analysis, S atoms occupy partially the oxygen sites leading to believe on the possible insertion of the dopant. The optical properties that include the band gap (Eg), reflective index (n), extinction coefficient (k), complex dielectric constants (ε), optical conductivity (σopt), dissipation factor (tan δ) and relaxation time (τ) were studied. The overall characteristics indicate that S-doping induced an improvement of the transparency, an accentuation of the insulating character and an important loss of energy under UV irradiation. However, the charges life-times are largely improved. The best photocatalytic activity toward the eosin degradation observed for the sample S0.2ZnO (k = 3.58 × 10−3 min−1) is attributed to the lowest σopt (3.4 × 107), a dissipation factor (1.66 × 10−7), and a higher relaxation time (1.22 × 10−15 s).