Preparation And Properties Of Modified Nano-TiO₂ And It Composite Coatings

Nano-TiO2 materials have great application values in wastewater treatment and air purification because of its high photocatalytic properties. Light absorption of nano-TiO2 powder is only limited in UV and nano-TiO2 has lower quantum yield. In this paper, rare-earth element or transistion metal element mono-doped nano-TiO2 and nonmetal element and metal element coped nano-TiO2 was prepaered to improve the properties of nano-TiO2 using sol-gel method. Catalyst is difficult to recovery and reuse when Nano-TiO2 powder were dispersed in water medium. To settle this problem, the nano-TiO2 particles were introduced into plating bath based on plating Ni-Co-P to make the nano-TiO2 particles and Ni,Co,P matrix co-deposit to obtain nano-TiO2 composite coatings. Microstructure, morphology and composition of doped nano-TiO2 and composite coatings were characterized by XRD, SEM and EDS techniques. The Micro-hardness of composite coatings was investigated as well as photocatalytic performance of doped nano-TiO2 and nano-TiO2 composite coatings.Ce-TiO2,Co-TiO2 and Zn-TiO2 powder was prepared by sol-gel method. The particle size and phase transformation process of one-element doped nano-TiO2 can be controlled by changing heat-treating temperature the one-element doped nano-TiO2 with small size and high purity were obtained. The result showed that temperature(500℃) was the best heat treatment temperature of the nano-TiO2 and the optimal concentration of the doping agent were 0.6, 0.5 and 0.8 % respectively. Correspondingly, photocatalytic decomposing rate of methyl orange solution were 67, 75 and 62% respectively.On the base of prepared Ce-TiO2, Co-TiO2 and Zn-TiO2 by sol-gel method, three kinds of powder were subjected to nitriding treatment. Doping nitrogen can improve the photocatalytic activities of TiO2. Their photocatalytic decomposing rate of methyl orange solution were up to 83, 94 and 76% respectively.The optimum process of electro-deposition of Ni-Co-P-nano-TiO2 composite coating is achieved: TiO2 content is 6g/L, bath temperature 60℃,surfactant content 200mg/L , stir speed 200r/min and current density 5A/dm2. The content of nano-TiO2 in the composite coating is up to 7.53%. The photocatalytic performance of Ni-Co-P-nano-TiO2 composite coating is slightly lower than nano-TiO2 powder.