Carbon Doped Metal Oxide Composite Structures For Photothermal Catalytic CO₂ Reduction

Photothermal catalysis is capable of converting CO2 into high value-added products(e.g.,carbon oxides,hydrocarbons,etc.),which is expected to alleviate environmental problems such as global warming and ocean acidification caused by excessive burning of fossil fuels.Metal oxides are abundant in source and inexpensive,and have broad application prospects.However,their high carrier complexation rate,weak photothermal conversion ability,and lack of high active sites on the surface(poor adsorption affinity)lead to their poor photothermal catalytic performance.To address this problem,this thesis enhances the photothermal catalytic performance by introducing carbon materials(CDs)into metal oxides and deeply investigates the photothermal catalytic mechanism.and the following studies were carried out:(1)To investigate the photothermal synergistic mechanism and its quantitative distinction between light and heat,we prepared a metal oxide photothermal catalyst,i.e.CDs-TiO2-x,and explored its light-thermal coupling mechanism by using it as a model.This photothermal catalyst consists of carbon dots(CDs)and TiO2.CDs can simultaneously emit light and heat under the action of infrared light,and TiO2 plays the role of stabilizing carbon dots,and through this stable coupling of light and heat to achieve super high photothermal catalytic performance.Compared with the undoped CDs TiO2 catalyst,the photothermal catalytic performance of CDs-TiO2-x can be improved by a factor of 1000,which is the highest value of the catalytic performance for metal-free semiconductor photothermal catalysts.(2)To investigate the mechanism of light-assisted thermal catalysis,we further synthesized a photothermal catalyst,i.e.C-ZnO,for infrared photocatalytic CO2 reduction.the doping of C makes this material highly capable of photothermal conversion.Under the irradiation of 10 W cm-2 IR light,the surface temperature of CZnO was 711℃,and the photothermal catalytic performance was 110.95 mmol g-1 h-1 with the product CO.This work lays the foundation for the development of IR lightresponsive photothermal catalysts.