Research On The Application Of Modified TiO₂ In The Photocatalytic Reduction Of CO₂

In the present era of energy supply dominated by fossil fuels,the significant emission of CO₂ into the atmosphere has resulted in severe environmental issues.Photocatalytic reduction process can achieve the transform of CO₂ into valuable chemical products and the conversion of solar energy to chemical energy,which contributes to achieve green carbon circulation.Among various photocatalysts,TiO₂exhibits numerous advantages,such as low cost,stability,and non-toxicity making it a hot topic in catalyst research and showing great potential in research of photocatalytic reduction of CO₂.While the catalytic performance of TiO₂ was limited by its poor light absorption and charge separation.In this paper,based on the core topic of CO₂photocatalytic reduction reaction,TiO₂ was modified at the atomic level,interface level and overall level to enhance catalytic efficiency.And the relationship between photocatalytic activity and light absorption,charge separation,and surface reactions was discussed,and different catalysts were constrcuted to obtain higher catalytic efficiency.The modification at the atomic level improved the absorption and charge separation properties of TiO₂,thus higher catalytic activity in the CO₂ reduction reaction were obtained.Among the heat treatment conditions,the catalyst prepared at250℃in N₂ atmosphere showed the highest catalytic activity.In Chapter 3,Ni O and Pd were modified on TiO₂ nanosheets,and higher activity and selectivity of CH₄ were obtained because of improvement of charge separation and introduction of active species.Higher charge separation efficiency were obtained because of the construction of heterojunction,And higher electron density on Pd drived the multi-electron reduction process of CO₂ to obtain CH₄ with high selectivity.Pd_1.0-Ni O_0.5/TiO₂ performed highest activity and selectivity of CH₄ in CO₂ photoreduction reaction.Compared to single-component modification,the synergistic effect between the dual co-catalysts is more beneficial for achieving efficient charge separation and improving product selectivity,which provides example for designing efficient photocatalyst.In Chapter 4,self-doped blue TiO₂ were prepared through reductive treatment and Cu₂O were further modified after a simple reduction reaction.Higher activity were obtained because the enhancement in light absorption and charge separation.Reductive treatment altered the electronic structure of TiO₂,resulting in bandgap narrowing and redshift in the absorption edge,at the same time,the defective sites generated by the thermal reduction facilitated charge separation.Z-scheme heterojunction were formed between Cu₂O and TiO₂ after the introduction of Cu₂O,enabling directional migration of electrons and holes and thereby improving charge separation efficiency.Cu₂O/BT exhibited 10 times higher activity than P25 because of the modification on atomic level and interface level,providing a case study for future photocatalytic design.In Chapter 5,photonic crystals with unique optical properties were combined with blue TiO₂ to enhance the light utilization efficiency of TiO₂.Secondary absorption of light by TiO₂ is achieved by exploiting the photonic crystal’s property of reflecting light at specific wavelengths.In this composite catalyst,the light absorption of TiO₂ was affected by the reflection intensity and photonic band width of the photonic crystal.The amount of TiO₂ loading determines the catalytic efficiency per unit mass and per unit area.Efficient utilization of light energy can be achieved by properly constructing multilayer reaction system.This work provides a strong basis for the application of photonic crystal supported catalyst in the photocatalytic reaction of CO₂.