Research On Performance Of Zeolite Imidazloe Frameworks Derivative Structure In Electrocatalytic Oxygen Evolution And Reduction Reactions

Since the first industrial revolution in the 18th century,the productive forces of human society have developed rapidly,and material civilization has been highly proseperous.However,after entering the 21th century,the rough development model has given rise to two major problems,environmental pollution and energy crisis,and has launched a severe challenge to the living space of mankind.In view of this,it is necessary to develop new types of energy storage and conversion equipment.Technologies such as Electrochemical Water Splitting and Metal-Air batteries have received widespread attention due to their low environmental pollution and high energy conversion efficiency.It is necessary to find a catalyst that can accelerate the reacyion of the corresponding electrode.At present,the commercial catalysts for Oxygen Evolution Reaction（OER）and Oxygen Reduction Reaction（ORR）are noble metal ruthenium（Ru）and platinum（Pt）,but ruthenium and platinum are scarce.And high costs severely limit their commercial development.Therefore,it is necessary to develop low-cost and high-acticity electrochemical catalysts.Metal-Organic Frameworks（MOFs）are a kind of three-dimensional porous crystalline materials formed by the interconnection of metal units and organic ligands.As an important branch of MOFs,Zeolite Imidazole Frameworks（ZIFs）are the preparation of high activity,high an ideal precursor for non-noble metal electrocatalysts with specific surface area and thermal stability.This article takes ZIFs as a starting point to study the application of its derivative materials in electrocatalysis,specifically in the following aspects:（1）Grow ZIF-67 polyhedrons in-situ on the cluster-shaped MnO₂ nanotubes synthesized in advance,and use this as the precursor,through high-temperature oxidation,phosphating and vulcanization,etc.,to obtain a series of Co-based compounds modify the composite structure of MnO₂ nanotubes.This series of composite structures inherited the cluster-like substrate of MnO₂ and the morphology of the three-dimensional framework of ZIF-67.After studying their OER performance,it is found that compared with the MnO₂ substrate alone,the performance of the composite structure has been significantly imporved.Among them,the performance of CoSx@MnO₂ is the best,with an overpotential of only 334mV at 10mA cm^-2.Futher study the electrochemical stability of CoSx@MnO₂,after 16 hours of cycles in alkaline solution,the current intensity of the initial current density of 85% or more can still be maintained,and after 1000 cycles of cyclic voltammetry scanning in the working voltage window,there is almost no change in electrochemical activity.（2）A large number of experimental and theoretical adta prove that carbon materials co-doped with transition metal species and nitrogen are a kind of potential ORR catalyst.In the process of synthesizing ZIF-8 crystal,after high temperature carbonization in an inert atmosphere,a carbon framenwork material Fe-NC@Co-GC with internal iron sites and external cobalt particles doped with carbon nanotubes is obtained.In alkaline solution,the limiting diffusion current can reach 6.37mA cm^-2 and the half-wave potential is 0.836V.Futher studying the catalytic reaction mechanism shows that Fe-NC@Co-GC can achieve an electron transfer efficiency close to 100%.The stability of the study found that the current density has almost no weakening after continuous working for 20000s and the 1000 cycle test also has no attenuation of the limiting diffusion current and half-wave potential.Fe-NC@Co-GC also shows excellent performance.Methanol tolerance,a series of test showed that Fe-NC@Co-GC has comparable activity to commercial Pt/C.Expanding such methods is expected to design more highly active and economical ORR catalysts.