N-functionalization Of Carbon Nanotubes And Their Application In Electrocatalytic Reduction Of CO₂

In recent years,the massive exploitation and utilization of fossil fuels has led to a sharp rise in the content of CO2 in the atmosphere,causing serious environmental problems.Electrocatalytic reduction of CO2 is one of the promising methods of fixing and converting CO2,which has great significance in solving environmental and energy problems.In many studies,the N heterocyclic molecules such as pyridine and its derivatives and thiophosphate have some catalytic activity on CO2.However,there is a clear defect in this homogeneous system,which is that the catalyst molecules need to be added to the electrolyte every time,and the catalyst molecules are difficult to recover.In order to solve the above problems,organically doped metals have been developed(trapping catalyst molecules in the metal frame)and made into an electrode applied to catalysis to obtain a significant catalytic activity.However,the steps for synthesizing catalyst molecules are complicated and have great limitations.Carbon nanotubes as one-dimensional nanomaterials with special properties that are not found in many metal materials,such as good conductivity,larger specific surface area and the particularity of its surface(which can be modified by groups),were widely used in the field of catalysis.Therefore,this paper mainly focuses on the N-functionalization of carbon nanotubes and their application in electrocatalytic reduction of CO2.(1)synthesis of Pt/MWCNTs-Py material and its application in electroreduction of CO2.The MWCNTs-Py material was prepared by modifying the molecule of pyridine catalyst on the surface of carbon nanotubes through simple diazotization reaction.The microstructure of materials was characterized by SEM and TEM.Using TGA,XPS and Raman spectroscopy to test the surface structure.Through these characterization methods,the successful functionalization of the modified group was studied,and the amount of the modified group and the metal load were investigated.The prepared electrode was used as the cathode.In the H-type electrolytic cell,the constant current electrolysis was carried out in the saturated CO2 atmosphere.The electrode materialsand current density were investigated accordingly.Through the detection of electrolyte,ethanol is the main product,with a small amount of acetone.The preparation method of N-functionalized carbon nanotubes is simple and it has good catalytic activity in electroreduction of CO2.(3)synthesis of MWCNTs-PTE materials and its application in electroreduction CO2.In the homogeneous catalytic system,the mercaptobutyl molecules with N heterocycles have been proved to have electrocatalytic activity on CO2 without metal.However,it is necessary to add the mercaptodiazine catalyst molecule in each electrolysis.The prepared materials were characterized accordingly.The material was prepared as electrode for electrocatalytic reduction,and it was found that the reduction product was mainly acetone.In the process of electrolysis,it was not necessary to add mercaptobutyl in the solution.The electrochemical properties of a series of composites were investigated,and it was found that the presence of metal in the electrode material was not conducive to the reduction of CO2.