Preparation Of Metal Phthalocyanine/Graphitic Carbon Nitride Composite Catalyst And Photocatalytic Reduction Of Carbon Dioxide

In recent years,with the rapid development of society,mankind’s demand for energy has increased.The global storage of fossil energy is limited and non-renewable.Its extensive use has brought about a series of environmental problems,such as increased carbon dioxide emissions,leading to the greenhouse effect.More and more serious,so there is an urgent need to develop green and renewable energy.Photocatalytic reduction of carbon dioxide using solar energy to convert carbon dioxide into more valuable chemical substances such as hydrocarbons（methane,methanol,formic acid,etc.）,not only can reduce greenhouse gases,but also provide a new energy conversion method.In recent years Widespread concern.However,most of the catalysts used for photocatalytic reduction of carbon dioxide are precious metal materials with scarce production,and expensive photosensitizers are required.Therefore,it is necessary to develop non-noble metal catalysts with high catalytic activity and low preparation cost to be used in this field.Taking this as a starting point,this paper studies two different metal phthalocyanine-based photocatalytic reduction carbon dioxide composite catalyst systems.Metal phthalocyanines（MPc,M=Fe,Co,Zn,etc.）have the advantages of highly conjugated structure,diversified coordination properties,and reversible redox activity.These characteristics give metal phthalocyanines the potential to prepare high-performance catalysts.Graphite carbon nitride（g-C₃N₄）is inexpensive and easy to prepare,has stable chemical properties and has a strong visible light response.In this paper,iron phthalocyanine（FePc）is uniformly loaded on the surface of g-C₃N₄.As a photosensitizer in the reaction system,g-C₃N₄ can effectively reduce the cost,increase the light absorption area to a certain extent,and improve the utilization rate of light energy.The successful loading of FePc was confirmed by characterization methods such as transmission electron microscope,X-ray photoelectron spectroscopy,and X-ray diffraction.The photoluminescence and transient photocurrent experiments show that the combination of FePc and g-C₃N₄ inhibits the recombination of photogenerated electron-hole pairs;the ultraviolet-visible diffuse reflection test shows that the combination of the two materials broadens the light absorption range of the catalyst.The performance of photocatalytic reduction of carbon dioxide was tested under the light of xenon lamp.The results showed that compared with g-C₃N₄,the photocatalytic activity of FePc/g-C₃N₄ composite catalyst was significantly enhanced,and it had higher performance of photocatalytic reduction of carbon dioxide.In the cyclic experiment,the catalyst can still show strong photocatalytic activity.In addition,in this paper,the FePc/g-C₃N₄ composite catalyst was loaded on polyester fiber（PET）for photocatalytic reduction of carbon dioxide experiment,which improved the powder catalyst’s shortcomings such as low light energy utilization and easy accumulation.The supported fibers were characterized by scanning electron microscopy,X-ray photoelectron spectroscopy and other methods,indicating the successful loading of the FePc/g-C₃N₄ composite catalyst.The ultraviolet-visible diffuse reflectance test is also used to confirm that the composite fiber has a wide spectral absorption range.The photocatalytic performance test results show that the supported fiber can exhibit a strong photocatalytic efficiency under the irradiation of sunlight,which indicates that the supported fiber has a high photocatalytic performance for reducing carbon dioxide.Based on the development of metal phthalocyanine and graphite phase carbon nitride composite materials,a composite catalyst based on covalent organic polymers（COPs）and g-C₃N₄was further constructed,and Co-Fe COPs/g-C₃N₄ photocatalysts were successfully prepared.Further improve the photocatalytic performance of the composite catalyst.Among them,g-C₃N₄is used as a photosensitizer,and Co-Fe COPs are used as the active center of carbon dioxide reduction.The porosity of the Co-Fe COPs/g-C₃N₄ catalyst structure significantly improves the absorption of carbon dioxide gas,and there are strong covalent bonds and periodic organic structural units inside.The special framework structure helps to fix carbon dioxide molecules.These structural features can effectively improve the performance of the catalyst for photocatalytic reduction of carbon dioxide.Using scanning electron microscope,infrared spectroscopy,X-ray photoelectron spectroscopy and other characterization methods to verify the successful preparation of Co-Fe COPs/g-C₃N₄ catalyst,and the specific surface area test showed that the catalyst under the same conditions,Co-Fe COPs/g-C₃N₄ catalyst can absorb more CO₂.Under the xenon lamp illumination,the Co-Fe COPs/g-C₃N₄ catalyst exhibits excellent photocatalytic reduction of carbon dioxide performance and cycle stability.In this paper,a photocatalytic reduction system with high catalytic activity is constructed,which provides a new idea for the development of artificial simulation of photosynthesis.