Preparation And Electrocatalytic Properties Of Two-Dimensional Material (MXene,Graphene)

Two-dimensional materials,such as MXene and graphene,are of great significance in the fields of electrocatalysis,photocatalysis and photocatalysis due to their unique structure and electronic properties with adjustable local band gap.However,the current preparation methods of two-dimensional materials are usually complicated and time-consuming,which limits their application in the field of catalysis.Therefore,taking simple and appropriate treatment methods to strip bulk materials into thin layers and increase their electrical conductivity to improve their catalytic performance is the focus of two-dimensional materials research.In this paper,we used simple two-electrode electrochemical cathodic stripping and four-electrode electrochemical cathodic stripping methods,respectively,to prepare a series of MXene and Graphene with different degrees of stripping by regulating voltages,temperatures,electrolyte concentrations electrochemical properties were alsostudied.The morphology of monolayer MXene is similar to Graphene,however,compared with the C-C monatomic structure of Graphene,the structure of MXene itself contains metal atoms,which is composed of the mixed valence bond of covalent bond-ionic bond-metal bond,so that it has excellent electrocatalytic nitrogen reduction performance.As for Graphene,we introduce copper ions on it to form graphene-based composite materials through electrolysis to improve its electrocatalytic oxygen reduction performance.In this paper,on one hand,a lot of research work has been done on the preparation of MXene and graphene matrix composites,and the preparation conditions have been optimized by using simple and novel methods.On the other hand,the electrochemical nitrogen reduction and oxygen reduction properties of the prepared materials were investigated.The specific work is divided into the following parts:1.By using strong acid etching and two electrode electrochemical cathodic stripping method,we have prepared a series of Ti₃C₂ catalysts.Through regulating preparation conditions such as concentration of hydrochloric acid,the proportion of lithium fluoride and titanium aluminium carbide and electrochemical cathodic voltage thin-layer MXene with accordion shape is successfully synthesized,Related electrochemical characterization shows catalyst processed by 30 V has relatively good nitrogen reduction performance.The Reason is that there are more titanium dioxide generated on 30 V processed MXene electrolysis,the formation of Ti O₂-Ti₃C₂ complexes is not only beneficial to the electronic transmission transformed,because of the transformed high conductivity Ti₃C₂but avoids the Ti O₂nanoparticles aggregation,At the same time,Ti O₂ nanoparticles have increased specific surface area of catalyst materials.Therefore,the excellent electrocatalytic nitrogen reduction performance of 30 V treated MXene is attributed to the synergistic effect between Ti O₂ and Ti₃C₂.2.The copper oxide/graphene composite was prepared by four-electrode electrochemical cathode stripping with graphite as cathode and copper wire as anode.The physical and chemical properties of the catalyst were controlled by adjusting the preparation conditions such as electrolysis voltage,electrolysis temperature,the proportion of electrolyte solution and the time of electrode in anode and cathode respectively.The electrocatalytic results show that the catalyst obtained at the electrolytic voltage of 30 V,the electrolytic time of 4 h and the solvothermal temperature of 160?has excellent oxygen reduction performance.The results show that the contents of Cu O and Cu₂O increase with the increase of electrolytic voltage.The Cu O_x/G-30 with the highest Cu O_x content showed higher current and lower overpotential than other samples,which was more conducive to the 2e^-oxygen reduction process and resulted in a hydrogen peroxide yield of up to 80%.