Synthesis and study of TiO2/CuO core shell nanoparticles for photovoltaic applications

Abstract Metal oxide nanomaterials have a great importance in the science and industrial world today. Titanium dioxide (TiO2) is a well-known oxide material and used in photovoltaic devices due to its high porosity, high stability and stable energy band gap. TiO2 can be doped with different materials such as gold and silver to enhance its structural and optical properties. In this work, we report the synthesis of TiO2/CuO core shell by sol-gel technique using titanium butoxide, zinc nitrate and copper nitrate as precursors. TiO2 is doped with CuO due to its good absorption efficiency and electrical properties. Moreover Fermi level of copper is 4.65 eV which is between gold (5.1 eV) and silver (4.26 eV) making copper suitable and cheap candidate to replace noble metals. Its atomic radius is approximately same as that of TiO2. The structure and optical properties of prepared samples are characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Fourier Transform Infrared (FTIR) and Ultraviolet/visible (UV–Vis) techniques. XRD data indicates an increase in the crystalline size from 4 to 7 nm on increasing the concentration of copper from 0.5 to 1.5 at% in sample 1–3 (TiO2: Cu (0.5–1.5 at%)). XRD and FTIR analysis confirms that Cu existed in TiO2 nanoparticles in the form of CuO. TEM images have shown that the nanoparticles of TiO2: Cu exists in spherical shape and exhibit core–shell structure. UV–Visible results reveal the decrease in TiO2 band gap energy with increase in doping concentration of Cu in TiO2. UV–Visible results also show high absorption in Cu-doped TiO2 as compared toundoped TiO2.