| Compared to the traditional preparation process of thin film, atomic layer deposition（ALD） is an excellent coating technology which can deposit extremely conformal thin films with atomic-scale control. It can also achieve excellent uniformity and precise thickness control at a lower deposition temperature. TiO2 as a semiconductor material is rarely used alone apart from used as pigment because of its brightness,high refractive index and resistance to discoloration. However, many TiO2-based modified materials have been widely used in energy and environmental areas including optoelectronics,photovoltaics, batteries, microwave absorption materials, catalysis, sensors and medical implants. Their performances in such applications depend largely on their structure,morphology, electronics, size, optics as well as surface properties.In this paper, we employed ALD technology to design and fabricate the TiO2-based nanocomposites and investigated their applications as microwave absorption material,photocatalyst and peroxidase-like enzyme. The main contents are as follows:1. Preparation and microwave absorption properties of TiO2/Ni-CF hierarchical nanostructuresBased on the research of the microwave absorption performance of ZnO@Ni, ALD used as a surface treatment technology to deposite various thickness of NiO coating layer on the surface of TiO2 nanowires, and the final TiO2/Ni-CF hierarchical nanostructures were obtained by using the TiO2/NiO composites as catalysts to grow carbon fiber （CF）through an insitu growth method. The density and morphology of CF can be easily controlled by changing the cycle numbers of ALD NiO. We investigated the microwave absorption properties of TiO2/Ni-CF composites by mixing 15% of the sample with paraffin and found that the CF contents and morphologies could obiously influence the absorbing performance of nanocomposites. The TiO2/Ni-CF prepared with 200 cycles of NiO as catalysts showed superior characteristics among all the samples. The effective absorption bandwidth below -10 dB reached 5.44 GHz with a thickness of only 1.8 mm.Moreover, when the match thickness is 1.6 mm, the minimum RL -32.26 dB can be achieved.2. The preparation of Au@TiO2 yolk-shell nanostructure and its application as photocatalyst and peroxidase-like enzymeA novel Au@TiO2 yolk-shell nanostructure was synthesized by integrating ion sputtering and ALD technology. By appropriately controlling the time of ion sputtering, the Au nanoparticles with controllable size and narrow size distribution confined in TiO2 nanotubes can be obtained. Their applications as visible photocatalyst and peroxidase-like enzyme were investigated. Au@TiO2 composites exhibited visible light photocatalytic properties towards the degradation of MB and the composite with the Au nanoparticles sputtering time of 80 s showed the highest photocatalytic performance. The investigation of peroxidase-like activity of Au@TiO2 nanocomposites showed that the Au-50@TiO2 possessed the highest peroxidase-like catalytic ability among all the samples. In addition, a method for colorimetric detection of H2O2 and glucose was established based on the peroxidase-like characteristics of Au-50@TiO2. The results indicated that the detection limits of 4.0 × 10-6 M for H2O2 and 3.5 ×10-6 M for glucose were achieved. |
