The Preparation Of Carbon-based Materials From Cobalt-based Metal Organic Framework And Their Oxygen Evolution Reaction Research

The adjustable porosity and controllable structure of metal-organic framework(MOFs)has attracted the attention of scholars.The derived materials prepared by using MOFs as sacrificial template retain the physical and chemical properties of the precursors,which has high research value.In this paper,the bimetallic MOF material ZnCo-ZIF was selected as the template to prepare a series of MOF derived carbon-based nanomaterials by changing the calcination conditions,which were used as catalysts for electrocatalytic reactions.Study shows the connection for carbon-based composites and oxygen evolution.The main contents are as follows:1.Preparation of NC-CNTs-Co and its application in electrocatalysis.The composites of Co,C and carbon nanotubes(NC-CNTs-Co)were prepared by one-step calcining using ZnCo-ZIF as template.The working potential of NC-CNTs-Co-9 was 1.589 V,and the corresponding overpotential was 359 mV,which showed good electrochemical activity and durability.In this paper,pyrolysis temperature is a key factor to increase electrocatalytic activity.Controlled pyrolysis temperature to obtain unique chemical composition and structure.First,NC-CNTs-Co-9 retained the octahedral shape,with the largest number of CNTs on the octahedral surface,which significantly improved the performance.Secondly,CNTs obtained in situ can reduce internal resistance and promote electron transfer,providing a large electrochemical surface area for OER.NC-CNTs-Co-9 has good electrochemical properties and chemical stability.In addition,the porous structure of NC-CNTs-Co-9,especially the mesoporous structure,shortened the electrolyte diffusion pathway and effectively increased OER activity.2.Preparation of NC-CNTs-Co3O4 and its application in electrocatalysis.Co3O4,carbon and carbon nanotube composites(NC-CNTs-Co3O4)were prepared by two-step continuous pyrolysis(carbonization-oxidation)using ZnCo-ZIF as template.NC-CNTs-Co3O4 showed excellent electric catalytic activity can be attributed to the following:first,ZnCo-ZIF derivative of NC-CNTs-Co3O4 composite material is composed of nitrogen doped carbon frame,carbon nanotubes and uniform adhesion of Co3O4 nanoparticles,this unique carbon skeleton structure to provide a channel for the electrolyte,the catalyst-close contact between the electrode and catalyst-electrolyte,thus promotes interfacial charge transfer.Secondly,the high surface area,abundant pore structure and rough skeletal structure connected to CNTs also play a crucial role in enhancing electrocatalytic activity and stability,as they enhance rapid charge,mass transport and good electrical conductivity between materials and electrolytes.In addition,Co atoms are oxidized into active centers Co3O4/CoOOH in this catalytic reaction,which activates the CoOOH through Co3O4,providing an effective electronic pathway to accelerate OER processes.In addition,the presence of nitrogen can further promote the interaction between electrons and C/Co3O4,and introduce more defect active sites.It is because of these special physicochemical characteristics that NC-CNTs-Co3O4 shows good electrocatalytic performance in alkaline electrolyte(At 10 mA cm-2,the overpotential is only 359 mV and Tafel slope is 82 mV dec-1).3.Preparation of NPC-CNTs-CoP and its application in electrocatalysis.Using ZnCo-ZIFs as the template,CoP,C and carbon nanotube composites(NPC-CNTs-CoP)were prepared by carbonization-oxidation-phosphating pyrolysis.NPC-CNTs-CoP have lower charge transfer resistance and better durability.Due to the unique characteristics of this structure,such as the synergy between CoP and nitrogen-doped carbon nanotubes,large specific surface area,porous channels,etc.,the resulting NPC-CNTs-CoP(P2)have good performance and good cycling stability in OER.NPC-CNTs-CoP(P2)had an overpotential of 224 mV in 1.0 M KOH,reaching a current density of 10 mA cm-2.