Research On The Regulation And Mechanism Of Electrocatalytic Properties Of Carbon Nanotubes

Carbon nanotubes are composed of coaxial tubes of nanoscale carbon molecules and have a graphite-like laminar structure.Due to the excellent mechanical properties,electrical properties and good chemical stability of carbon nanotubes,this paper takes carbon nanotubes as the research object,the preparation of a variety of carbon catalyst,studied the electric catalytic performance,discusses the relationship between the structure and electrochemical properties of materials,put forward two kinds of different oxygen catalytic mechanism,analysis of the metal nanoparticles and the synergistic effect between the carbon materials,and carry out such materials in research and application of the zinc air battery and water splitting,which have become the most promising research hotspot in the field of nanomaterials.The details are as follows:First,the active sites of electrocatalysis of carbon nanotubes?CNTs?are not clear yet and highly debated in literatures.In this work,we proposed a novel strategy,taking advantage of the nature differences of electron structures between s-and m-SWCNTs,to explore the effect of density of electronic states?DOS?of SWCNTs on the electron transfer,and found that the DOS play a dominant role on their electrocatalytic activities for oxygen reduction and evolution reactions.In SWCNTs,the DOS was hovering over the carbon atoms,thus the carbon atoms in the?-?conjugated system of SWCNTs,as carriers of DOS,are the electrocatalytic active sites.This result could be a fundamental theoretical basis for developing SWCNTs based metal-free electrocatalysts.Second,to explore the activity of low metal content,stability,cost-effective acidic OER catalyst for sustainable water oxidation is of great significance,in this paper,through a simple thermal oxidation and oxygen protection were prepared under the condition of hydrothermal method with carboxyl of multi-walled carbon nanotubes?ce-MWCNTs?after different levels of oxidation,with the change of the hydrophilic and electric conductivity,we study the performance and conditions of the optimal?3.9-ce-MWCNTs?with superior OER the performance in acid system,when the current density of 10 mA cm^-2,Its overpotential is 265mV,higher than commercial RuO₂,and has a low tafel slope(80 mV dec^-1).The introduction of carboxyl group can not only guarantee the hydrophilic and electrocatalytic stability of carbon nanotubes.Moreover,the carboxyl group with strong electron absorption reduces the electron state density near Fermi energy level,making adjacent carbon the target of charge transfer for H₂O molecular adsorption.Third,exploration of cost-effective,high-performance and durable multifunctional electrocatalysts is of significant importance for renewable energy conversion and storage,such as metal-air batteries and water splitting.In this work,a simple strategy is developed to tailor the nickel metal with the collaboration of nitrogen-doped graphene and single-walled carbon nanotubes.The resulted nickel catalyst exhibits superior trifunctional activities for oxygen evolution?OER?,hydrogen evolution?HER?,and oxygen reduction reactions?ORR?,in the same electrolyte,even comparable to commercial Pt/C and RuO₂ respectively,which can be attributed to the synergistic advantages between nickel,nitrogen and carbon,mainly including abundant integrated active sites achieved by the irregular charge distribution among C-N and Ni-N coupling centers.In addition,the collaborative functional bonds also boost the effective adsorption and desorption,and single-walled carbon nanotubes enhanced the surface area and the electron mobility with the superior dispersive capacity and electrical conductivity.Such remarkable effects on trifunctional catalysis elicit the efficient overall water splitting,and endow the assembled zinc-air battery with a good performance.Therefore,it is necessary to select two different carbon nanomaterials to promote nickel as an advanced multi-functional electrocatalyst.