| Titanium dioxide (TiO2) as non-toxic, stable, low cost and high efficient photocatalyst has attracted much attention in photocatalysis chemistry over past several decades. But the band gap of TiO2 is so wide that it only absorbs ultraviolet light, which accounts for just 4% of solar irradiation, and the light electrons and holes is easy to compound, leading to a lower utilization of sunlight and quantum conversion efficiency. To overcome this problem, versatile strategies based on physical or chemical methods have been applied to harvest more light irradiations and extend the optical response range of TiO2. This thesis mainly focuses on doping and physical structure optimization to expand the response of the light, and improve the photocatalytic activity and the photocurrent intensity.Porous structure materials are often used as catalytic materials, especially for the three-dimensional orderly porous structure of photonic crystal. In photonic crystal, slow light effect can be observed, which means the light near its photonic stop band edges undergoes multiple scattering and travel with very low group velocity. As a result, the light near the photonic stop band is largely absorbed due to the slow light effect which has been widely applied to improve the intrinsic optical response of the material for improving its photochemical performance. Therefore, inverse opal structures have great advantages in improving the photo catalytic activity.The main content and results of the work are as follows:1. The PS photonic crystal was used as template to successfully prepare photoelectric CuO-TiO2 three-dimensional inverse opal structure (IOS). The designed photocatalysts exhibit not only a very high surface area but also photonic behavior and multiple light scattering, which significantly increased visible-light absorption. Thus the corresponding photocurrent density and photocatalytic efficiency of CuO-TiO2 inverse opals prepared at the optimized condition for the degradation of organic dye (methylene blue) show highly enhanced values by 5.1 and 3.25 times compared with the nanoparticle TiO2. It is a valuable method to prepare new kinds of photoelectric materials applied in clean energy, water treatment and so on.2. We have used PtOEP to sensitize TiO2 IOS for enhancing light harvesting. This is the first demonstration of PtOEP modified on porous photonic crystals. The results show that PtOEP sensitization and unique inverse opal structure are responsible for the observed expanded photo response of PtOEP/TiO2 inverse opal. The corresponding photocurrent density and photocatalytic efficiency of PtOEP-sensitized TiO2 inverse opals prepared at the optimized condition for the degradation of methylene blue showed highly enhanced values by 6.3 and 3.9 times compared with the TiO2 nanoparticles. Our work suggests that the coupling of photonic band gap structure with PtOEP sensitization is a promising approach to achieve maximum improvement for various photocurrent and photocatalytic materials, especially for environmental applications and solar cell devices. 3. The porous TiO2 was prepared as the electrode material of lithium battery for increasing specific surface area and decreasing volume expansion phenomenon in the process of charging and discharging. At the same time, because TiO2 is low electrical conductivity, we carry on the further doping metal compounds (FeCl3) for reducing the impedance. The combination of these two methods can improve the effect of the charge and discharge capacity of the TiO2 materials, as well as cycling stability. The porous structure design of TiO2 make the specific surface area increased from 16.67 m2/g to 61.63 m2/g. After doping of iron ion the impedance values decreased from 330Ω to 95H. As anode materials, the as-obtained Fe-TiO2 shows a reversible capacity as high as 142 mAh/g increased by 1.35 times compared with pure TiO2 nanoparticles at the current density of 100 mA/g for 100 cycles, which is potential for practical application in lithium-ion batteries. Besides, the sample also exhibit high rate performance. |
PDF Full Text Request