Design and tuning functionality of rod-like titanium dioxide–nickel oxide composites via a combinational methodology

TiO₂–NiO composite nanorods were synthesized by combining hydrothermal growth of TiO₂ nanorods and sputtering deposition of NiO film. Crystalline NiO coverage films with various thicknesses were sputter coated onto TiO₂ nanorods by controlling NiO sputtering duration. The crystallographic analyses demonstrate that crystalline rutile TiO₂-cubic NiO composite nanorods were formed herein. In comparison with pristine TiO₂ and NiO, the coverage of NiO crystals on the TiO₂ nanorods led to an enhanced photodegradation activity of the TiO₂–NiO composites towards Rhodamine B dyes under irradiation. Moreover, the TiO₂–NiO composite nanorods with the adequate content of NiO coverage layer show superior gas-sensing responses to 25–200 ppm ammonia gas in comparison with those of the constituent counterparts. The experimental results herein demonstrate that decoration of NiO film on the surfaces of TiO₂ nanorods with tunable coverage sizes via sputtering deposition is a promising approach to design TiO₂–NiO composite nanorods with desirable functionalities. (paper)