| After coming into the 21st century, current energy shortages and environmental pollution have become the worldwide focus problems. The large amount of CO2 emission impacts climate change causing global-threatening greenhouse effect. Using solar-powered photocatalytic technology to convert CO2 into hydrocarbons has both theoretical and practical significances, which is considered as the most promising methods for the fixation and transformation of CO2. TiO2 nanomaterials plays a crucial role in the field of photocatalysis research, investigates as the promising and prospective candidate for photocatalysis technique owing to its advantages, such as strong oxidized ability, stable chemical properties, environmentally benign, inexpensive and obtained easily, bringing no secondary pollution.In this paper, we employd different synthesis methods to obtain porous TiO2 film, Ag/Pt-TiO2 nanorods film. Various material characterization methods such as SEM-EDS, AFM, XRD, XPS, UV-vis and PL were used to characterize the structure, crystallinity morphology and chemical state of the fabricated photocatalysts. The photocatalytic activities were investigated by the photoreduction of CO2 using gas chromatograph analysis under different conditions and explored its mechanism primarily. What is more, the electrostatic field within the CO2 photoreduction system was proposed for highly efficiency CO2 photoreduction. The main contents of the dissertation are as follows:1)、The TiO2 films with unique porous structures have been successfully obtained on Ti plates by a simple hydrothermal treatment using H2O2 solution. The porous TiO2 thin film with excellent appearance exhibit extremely high photocatalytic activity and stability. The samples were used as photocatalysts to reduce CO2 under simulated sunlight irradiation at room temperature in the presence of H2O. The films have excellent grid-like structures, providing more active photocatalysis sites and exhibiting extremely high CO2 photoreduction efficiency with favourable selective formation of CO and CH4 with the highest production rates of 115μmol/g h and 12μmol/g h, respectively. The substantial Ti3+ and oxygen vacancies is the critical factor for the excellent photocatalytic performance.2)、The oriented TiO2 nanorods were synthesized by a hydrothermal method. Ag/Pt nanoparticles were then deposited on the TiO2 by photocatalytic reduction method. The Ag/Pt nanoparticles highly distributed on the TiO2 nanorods with good shape and less than 20nm in the diameter dimension. The oriented TiO2 nanorods with Ag or Pt nanoparticles exhibited higher CO2 photoreduction efficiency compared with the pure TiO2 nanorods, with maximum CH4 yield rates up to 1.0μmol/g h. The improvement in the CH4 yield was attributed to the formation of the Schottky barrier and surface plasmon resonance.3).. Adopting a simple hydrothermal method to synthesize TiO2 nanorods, which were direct epitaxial on FTO glass surface. Subjecting an applied electrostatic force of various strengths to the photoreduction of CO2. The maximum CH4 yield rates up to 184.44nmol/g h and the highest CO2 photoreduction quantum yield achieves 6.26%. The promoting effect of electrostatic force for the photoreduction of CO2 is getting better and better with the increasing voltage in the range of 25KV-45KV. |
PDF Full Text Request