Preparation And Photocatalytic Properties Of NiO/TiO₂ Nanobelts Heterostructure

Inorganic nanocrystals with designed structure have attracted much recent research activity due to their unique properties and potential applications in a wide range of areas including optical, electrical, magnetic, chemical, and catalytic devices. Since the discovery of carbon nanotubes in 1991, much interest has been focused on the one-dimensional nanostructures due to their exceptional electric, mechanical, and chemical properties. TiO₂ has been widely investigated as a photocatalyst due to its low cost, non-toxic nature, long-term stability and considerably high photocatalytic activity. As is well known, TiO₂ nanoparticles used as photocatalytic materials are difficult and costly to recycle. Numerous studies have been reported on the heterostructures of a multilayer thin film, a typical two-dimensional (2-D) nanostructure, zero-D (quantum dots) and one-D heterostructures have demonstrated several unusual optical and structural properties.In this work, nano-p-n junctions consisting of NiO NP/TiO₂ NBs and NiO NP/TiO₂ coarsened NBs, which comprise a typical heterostucture were synthesized with the goal of improving the photocatalytic properties of TiO₂ nanobelts based on a nano-p-n junction design containing NiO and TiO₂. This simple and efficient approach can be considered to be a facile, controllable and generic way for preparing advanced nano-p-n junction composite photocatalysts.The main contents and conclusions are as followings:(1) H₂Ti₃O₇ nanobelts and TiO₂ nanobelts were prepared via an alkaline hydrothermal process in concentrated NaOH aqueous solution.(2) Surface-coarsened H₂Ti₃O₇ nanobelts were prepared by an acid-assisted hydrothermal approach.(3) The photocatalytic activity of TiO₂ nanobelts and the surface-coarsened TiO₂ nanobelts was investigated by means of the photodegradation of MO. The pristine TiO₂ nanobelts exhibit poor photocatalytic activity.(4)Based on the preparation of TiO₂ nanobelts, NiO NP/TiO₂ NB and NiO NP/TiO₂ SC NB were prepared through a chemical precipatation method. Compared with the other photocatalysts studied in this work, NiO NP/TiO₂ SC NB proves to be a maximum photocatalytic material with high MO degradation activity driven by ultraviolet light. (5) NiO NP/TiO₂ NBs and NiO NP/TiO₂ coarsened NBs were prepared through a chemical-solution-deposition-decomposition process. NiO nanoparticles were assembled on the surface of TiO₂ nanobelts or surface-coarsened TiO₂ nanobelts, to form a large number of NiO/TiO₂ nano-p-n junction heterostrucutures.(6) The novel photocatalytic activity of NiO NP/TiO₂ coarsened NBs is attributable to the large surface area and plentiful photolysis-active planes produced by the acid-hydrothermal process and the nano-p-n junction heterostructure.