Synthesis Of Covalent Organic Frameworks For Electrocatalytic Hydrogen Evolution

Electrolytic hydrogen evolution is an ideal and clean method for hydrogen evolution.In recent years,the scientific community around the world has focused on the development of new cheap and sustainable electrocatalysts to achieve electrolytic hydrogen evolution large-scale application.Covalent organic frameworks（COFs）are a kind of excellent electrocatalysts with high superiority.Mainly include the following advantages:high porosity,which is conducive to proton transport;high specific surface area;a crystal with long range order promotes charge transport and separation;building blocks can be modified at the molecular level,with a high degree of tunability;high stability;metal sites can be reserved for later modification.Inspired by the above,COFs were selected for structural design and post-modification and applied to electrolytic water hydrogen evolution,the main research contents are as follows:1)Synthesis of COFs/metal ion doped for electrocatalytic hydrogen evolution.In this paper,a kind of COFs（ILCOF-1）with high crystallinity connected by imine bond was synthesized by solvothermal method and ILCOF-1 was used as a’platform’to synthesize a series of ILCOF-1-M²⁺containing metal ions.The results of electrochemical hydrogen evolution experiments show that the overpotential of ILCOF-1-Pd²⁺containing metal Pd²⁺is 117 m V,the slope of Tafel is 40 m V·dec^-1,it has excellent electrocatalytic hydrogen evolution activity.2)Synthesis of CTF-1 supported C₆₀ composites for electrocatalytic hydrogen evolution.In this paper,CTF-1 was synthesized by superacid catalysis and C₆₀ was loaded onto the surface of CTF-1 to solve the inherent problem of poor conductivity of CTF-1 and reduce the mass transfer resistance.The results of electrochemical hydrogen evolution experiments show that the impedance of the material decreases after doping with C₆₀.When the current density is 10 m A·cm^-2,CTF-1@C₆₀-3 has an overpotential of 62 m V,the electrocatalytic activity has been greatly improved.3)Synthesis of CTFs with different stacking modes for electrocatalytic hydrogen evolution.In this paper,highly crystalline CTFs with two stacking modes of AA and AB were synthesized in two steps by super acid catalysis and this method was extended to synthesis fluorinated CTFs.The results of electrochemical hydrogen evolution experiments show that F-CTF-1-AA has high catalytic activity,the overpotential is 200 m V when the current density is 10 m A·cm^-2,which has a great progress compared with the previously reported activity of non-metallic intrinsic COFs in electrocatalytic hydrogen evolution.