TiO2形貌調(diào)控及其對光催化CO2還原活性的研究.pdf

1、With the rapid increasing of enormous challenges in energy demands and environmental pollution ignited by fossil fuels consumption, developing of renewable and green technologies for energy production has aroused widespr

2、ead concern in the past few decades. Among various proposed technologies, semiconductor-based photocatalysis for CO2 reduction have been known as one of the most perspective strategies because of its potential in renewab

3、le energy creation and environmental remedies. In details, photocatalysis CO2 reduction can transform the green-house gas (CO2) into the valuable solar fuels such as CH4, HCO2H, CH2O and CH3OH. This outstanding ability o

4、f the photocatalysis CO2 reduction is the main motivation for the searching of efficient and visible-light active photocatalyst. After years of research and development, many semiconductors have been assayed and explored

5、 to be used as an effective photocatalyst for photocatalysis C02 reduction, such as TiO2, CdS, g-C3N4, ZnO and Bi2WO6. However, the practical application of photocatalysis CO2 reduction is still limited by its low CO2 co

6、nversion efficiency due to the fast charge carriers recombination and low light utilization. Among these semiconductors, TiO2 has regarded as the most promising photocatalyst because of its low cost, environmentally frie

7、ndliness and excellent photostability. However, TiO2 owns low photoconversion efficiency even in the UV-region due to its large bandgap, less photocatalytic reaction site, low electron mobility and short minority carrier

8、 diffusion length. Several strategies have been carried out to improve the photoconversion efficiency of the TiO2, such as extending the TiO2 absorption to visible light, boosting electron and hole lifetimes through dopi

9、ng and loading metals, and increasing the surface area by building a porous structure.
　　Morphology tuning is an effective way to enhance the photocatalytic activity of the photocatalyst. Nowadays, there is an enormou

10、s interest in controlling TiO2 morphology due to their fascinating shape-dependent physicochemical properties The advancements of the nano-sized semiconductor has arisen much attention from the scientific community. Due

11、to the rapid growth of the nano-materials, researches on the nano-sized TiO2 for photocatalysis applications are also under fast-paced evolution, and a lot ofinteresting and stunning finding have been made in the past fe

12、w years. It is apparent that the smaller size of the TiO2 can lead to the enhancement of specific surface area, which is beneficial for creating more reaction site for the photocatalysis reaction. Moreover, with the prop

13、er morphological tuning, the photoinduced charge carriers can be migrated to the surface of the TiO2 rapidly, resulting in fast photocatalytic reaction. Therefore, much studies and researches have been carried out in the

14、 shape-controlled synthesis of TiO2 for enhancing photocatalytic activity. In addition, synthesis of complex and hierarchical hetero-nanostructures has been introduced to boost the photoinduced electron-hole pair's separ

15、ation and enhance light absorption efficiency of the TiO2 for enhancing photocatalytic activity.
　　Herein, we report for the first time the photocatalytic reduction of CO2 0ver anatase TiO2 with truncated octahedral b

16、i-pyramid morphology prepared by hydrothermal method were examined. Moreover, the effect of the ratio of co-exposed {001} and {101} facets on the aforementioned reduction process. Further, a new"surface heterojunction" c

17、oncept is proposed on the basis of the DFT calculations to explain the difference in the photocatalytic activity of anatase Ti02 with co-exposed {001} and {101} facets.
　　Thereafter, Ag loaded TiO2 nanotube arrays (TN

18、TAs) were prepared by simple electrochemical anodization of Ti foil in fluoride-based electrolytes, followed by electrochemical deposition of Ag into the TNTAs, overcoming the serious limitations of the conventional powd

19、er nanomaterials, the need for post-treatment separation in a slurry system. Moreover, the electrochemical deposition of Ag is expected to overcome the capillary effect of TNTAs and Ag NPs can be directly deposited into

20、the interior of Ti02 nanotubes. The evenly distribution of Ag NPs can enhance the SPR effect, which is beneficial for enhancing the photocatalytic activity of the photocatalyst.
　　Then, a simple and novel anodization

21、and calcination method was implemented to prepare reusable TiO2 photonic crystals. Then, a novel method was prepared to evaluate the photocatalytic CO2 reduction activity of the samples. Through this method, the PBG of t

22、he TiO2 photonic crystal could be varied either into or out of the electronic absorption band of the TiO2 during the photocatalytic CO2 reduction. In order to determine the superior properties of the Ti02 PCs, Ti02 nanot