Design And Exploration Of Photothermal Catalytic CO₂ Reduction Performance And Selective Control

At present,the rapid development of the chemical industry is heavily dependent on fossil fuels,a traditional energy source.However,fossil fuels are typical non-renewable resources,and their use will release toxic gases and large amounts of carbon dioxide,which in turn leads to a series of ecological and environmental problems including the "greenhouse effect".Artificial carbon dioxide reduction is a green technology that converts carbon dioxide into high-calorie fuels,which not only reduces dependence on non-renewable energy sources,but also minimizes the impact of fossil fuels on the environment.In recent years,photocatalysis and thermal catalytic carbon dioxide reduction have attracted widespread attention from researchers,and they are an important research frontier in the field of carbon dioxide reduction.However,this technology usually has some restrictive factors,such as harsh reaction conditions,low catalytic efficiency,difficult to control selectivity,poor catalyst stability,and unclear reaction mechanism.Therefore,there is an urgent need to develop an efficient and controllable carbon dioxide reduction method.As an organic combination of photochemical and thermal catalytic pathways,photothermal catalysis is a promising carbon dioxide reduction technology.For a long time,people’s research in the field of photothermal catalytic carbon dioxide reduction has mainly focused on the catalyst itself,including size adjustment,structure improvement,morphology optimization,etc.However,the improvement of reaction conditions,the interaction mechanism of multiple components in the composite system,the regulation of photothermal properties and selectivity,and the photothermal mechanism are less studied.Therefore,in view of the current problems faced by photothermal catalytic carbon dioxide reduction,this thesis conducts scientific and systematic research from the perspectives of improving reaction conditions,enhancing photothermal efficiency and regulating selectivity,and discusses and discusses the related mechanisms involved.Elaboration.The specific research content is as follows:The first chapter systematically introduces the research background,basic principles and current technical routes of carbon dioxide reduction,points out the key problems faced by traditional photocatalysis and thermal catalytic carbon dioxide reduction,and expounds the research of new photothermal technology in the field of carbon dioxide reduction Progress,discussed the main factors restricting the efficiency of photothermal catalysis at this stage.Then put forward the method and strategy,research content and topic meaning of this thesis.The second chapter explores the synthesis of Cu/ZnO composite material and its photothermal catalytic carbon dioxide reduction activity,and discusses its photothermal synergy mechanism in depth.A simple precipitation method was used to synthesize a Cu/ZnO nanoparticle.The experimental results show that the plasmon resonance effect of Cu effectively improves the light absorption capacity of the material after the combination of the two,and exhibits excellent photothermal carbon dioxide hydrogenation under normal pressure.Performance,CO selectivity is as high as 100%.At the same time,the photothermal performance of the catalyst is 12.5 times that of pure heat.Further experimental exploration shows that this performance improvement is due to the photothermal synergistic effect of Cu/ZnO.After ZnO and Cu are co-excited,the photogenerated electrons generated enhance the adsorption of CO2 and H2,improve the stability of the reaction intermediates,and thereby improve the overall light energy utilization rate and photothermal carbon dioxide reduction efficiency of the catalyst.Chapter 3 mainly explores the effects of light intensity,light-heat temperature,copper-zinc molar ratio and Ar/H2 reduction temperature on Cu/ZnO light-thermal carbon dioxide reduction performance and selectivity.The study found that changing the external factors such as light intensity and photothermal temperature only affects the Cu/ZnO photothermal CO2 reduction efficiency without changing the reaction product selectivity,and as the light intensity and photothermal temperature increase,the CO2 reduction efficiency gradually increases.Changing the copper-zinc molar ratio and Ar/H2 reduction temperature will simultaneously affect the catalytic efficiency and the selectivity of the reaction products.The experimental results show that when the reduction temperature is 300℃ and the copper-zinc molar ratio is 1:1,Cu/ZnO exhibits a negative effect.The high selectivity of CO.When the reduction temperature is 300℃and the molar ratio of copper to zinc is 1:2,Cu/ZnO shows high selectivity to CH4.Further tests show that the reason for the difference in performance is the difference in the combination of copper and zinc in each sample and the difference in the degree of copper reduction.Chapter 4,based on the idea of adjusting the crystal plane,mainly explores the difference in the photothermal carbon dioxide reduction performance of TiO2 with different crystal phases.The experimental results show that anatase phase TiO2(A-TiO2)and rutile phase TiO2(R-TiO2)have a significant photothermal synergistic effect.The specific performance is that the performance of A-TiO2 photothermal CO2 reduction is 18.87 times that of thermal catalysis.R-TiO2 does not have the ability to reduce CO2 under light or thermal catalysis alone,but exhibits high selectivity to CO under light and thermal conditions.The introduction of light energy has little effect on the reduction ability of brookite-phase TiO2(B-TiO2)CO2.Further tests showed that A-TiO2 and R-TiO2 produced oxygen vacancies during the heating process,which not only broadened the absorption band edge and improved the utilization of light energy,but also enhanced the adsorption and activation of CO2 molecules,thereby greatly improving the catalysis effectiveness.The fifth chapter summarizes the research content of this paper,focuses on the analysis of the innovations and shortcomings of this paper,and looks forward to the next step.