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.