Na doped CuO as a new Day- Night (Photo) Catalyst

Oxide semi-conductors such as TiO 2 , ZnO, CuO have been extensively studied for long time for its photocatalytic activity and its application in waste water treatment. These semiconductors on excitation with UV or visible light generate e − -h + pairs that react with O 2 / H 2 O respectively to produce Reactive Oxygen Species (ROS) such as O 2 −• , • OH radicals. These ROS degrade the contaminants in water. There is a need for catalysts that produce these ROS even in absence of light (dark) and such Day-Night catalysts are significant from the point of view of 24 × 7 operation. Towards this objective, Na doped CuO , Cu 1 −x Na x O (x = 0 to 0.1) has been synthesized, characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), X-Ray photoelectron spectroscopy (XPS) and Ultra violet visible-diffuse reflectance spectroscopy (UV-DRS). The particle size of Cu 1 −x Na x O is in the range of 25 to 75 nm. Its photocatalytic activity has been reported for the first time. These compositions exhibit Photocatalytic activity in dark (in absence of light) too and is attributed to super oxide species generated due to vacancies created esp in Na doped compositions. Hence, the Na doped CuO acts as Day-Night catalysts and the rates of degradation are higher than those reported earlier for CuO. Reactive Oxygen Species (ROS) liberated from its aqueous suspensions have been estimated and correlated to its activity.