The Fabrication Of MOFs Derived Carbon Supported Transition Metal-based Electrode Materials And Their Performance

Energy storage,conversion and the development of new energy are the key factors to meet today’s energy demand,in which hydrogen energy and lithium-ion batteries have been widely researched and applied.It is significant to develop new electrode materials with high catalytic activity and stability to improve the performance of hydrogen and lithium storage.Metal organic frameworks（MOFs）have been widely used in biological drug loading,photoelectrocatalysis and lithium-ion batteries due to their large specific surface area,high conductivity and adjustable pore size.This paper,three novel electrode materials N-C@Co/Ni HDNCs,N-C@Co P/Ni₂P and Co O/Co Se₂-N,Se-C were stnthesized based on MOFs.The specific research contents are as follows:（1）The ZIF-8@ZIF-67 was used as precursor and dimethylglyoxime nickel as nickel source.The composites of rich nitrogen hollow nanocage carbon skeleton supported bimetallic single-atom Co/Ni were prepared by the strategies of room temperature stirring and high temperature pyrolysis.Various characterization results show that this material not only contains bimetallic single atom Co/Ni active sites,but also has large specific surface area,abundant N-doping,carbon nanotubes and defect sites.As the anode of lithium-ion battery,it possesses a high discharge specific capacity of 462.1 m Ah g^-1 after 500 cycles of charge/discharge at 0.5 A g^-1.Simultaneously,this composite also exihibit good rate performance and high lithium ion diffusion coefficient(6.32×10^-18 cm² s^-1).In addition,the theoretical calculation shows that the Co/Ni active sites with bimetallic single atom have more moderate Li affinity than single metal simgle-atom or no single-atom.,which can make the Li⁺can be quickly embedded and removed,and ultimately improves the cycle stability and rate performance of the material.（2）The ZIF-8@ZIF-67 was used as precursor and dimethylglyoxime nickel as nickel source.The multicomponent composite catalyst N-C@Co P/Ni₂P was synthesized by room temperature stirring and low temperature oxidation-phosphating strategies.When used as electrode material for electrocatalytic hydrogen evolution,the overpotential is 153 mV and 176 mV respectively at the current density of 10 m A cm^-2 in acid ang alkaline conditions.The corresponding Tafel slope values are 53.01 mV dec^-1and 85.65 mV dec^-1,and the TOF values are 8.59×10^-1 s^-1 and 8.417×10^-1 s^-1,respectively.The outstanding catalytic performance is mainly owe to the high catalytic activity of atomic Co/Ni active site and the strong synergistic effet between Co P and Ni₂P.（3）ZIF-8 was used as template,the nitrogen doped graphed carbon shell coated Co O/Co Se₂ nanoparticles electrode material Co O/Co Se₂-N,Se-C was constructed by room temperature stirring and partial surface oxidation selenization strategies.The XRD results show that the process of selenization is not only benfitical to the formation of Co Se₂ active species,but also can transform the amorphous Co O to crystalline Co O with higher catalytic activity.Co O/Co Se₂-N,Se-C shows good electrocatalytic performance for HER in acidic and alkaline media.The overpotential are 240 mV and 235 mV at 10 m A cm^-2 respectively,and the corresponding Tafel slope are 62.11 mV dec^-1 and 90.95 mV dec^-1.