Application Of ZIF-8 Derived Nanomaterials In Electrocatalytic Oxygen Reduction Reaction

In the face of increasing environmental pollution and energy crisis,it is urgent to develop energy equipment with low energy consumption and no pollution.Fuel cells are considered to be the most promising green power generation technology.But at the same time,its cathodic oxygen reduction reaction usually requires a high overpotential due to the slow reaction kinetics and rate lag,so a catalyst is needed to accelerate its kinetics.The current electrocatalysts used in ORR are mainly Pt-based catalysts.The scarcity and high cost of such catalysts limit the large-scale commercialization of electrocatalysts.The development of cheap and efficient non-precious metal catalysts also needs to be put on the agenda as early as possible,so Better catalytic efficiency and durability with Pt-based catalysts.ZIF-8 is a three-dimensional zeolite-type imidazole framework with excellent chemical and thermal stability.Its derivative materials have been widely used in electrocatalytic ORR.In this paper,ZIF-8 is used as the precursor to explore the preparation of non-noble metal catalysts and the performance of electrocatalytic ORR.The rotating disk technology and physical characterization methods are used to study the catalyst pair.The effect of ORR catalytic activity and the active site of the catalyst.The specific research content is as follows:1.ZIF-8 was successfully prepared by hydrothermal method,and the metal-free nitrogen-doped porous carbon catalyst NC-1000 was obtained by high-temperature calcination using ZIF-8 as a precursor.The NC-1000 was used in electrocatalytic ORR to find that The catalyst has good oxygen reduction catalytic activity under alkaline conditions.Further analysis showed that the electrocatalytic activity of NC-1000 may be attributed to the synergistic effect of its high degree of graphitization and a high proportion of pyridine nitrogen atoms.2.Theoretical calculations show that copper has the highest ORR catalytic activity among transition metals.A copper isolated sites catalysts(Cu ISs/NC-1000)anchored on a nitrogen-doped porous carbon was prepared by a simple hydrothermal-high temperature calcination strategy.The high temperature pyrolysis of Cu @ ZIF-8 as a precursor effectively prevented the migration and agglomeration of Cu atoms,thereby forming a well-defined copper single active site catalyst.Under basic conditions,it exhibits better ORR catalytic activity,durability,and resistance to methanol poisoningthan commercial Pt / C.The excellent ORR catalytic performance of Cu ISs /NC-1000 catalyst can be attributed to the single active site of copper anchored on the surface of N-doped carbon material and the auxiliary effect of N-doped carbon support.3.A single transition metal-doped electrocatalyst has a single active site and insufficient catalytic activity.The design and preparation of bimetal-doped carbon material catalysts has certain research value.The Fe-Ni co-doped porous nitrogen-carbon catalyst(0.05Fe/Ni-NC)was prepared using ZIF-8 as a precursor through two high-temperature calcinations.Characterization proves that the high ORR catalytic activity is attributed to the catalyst’s high degree of graphitization,uniform microporous structure,large specific surface area,and the coordinated effect of pyridine nitrogen and graphitized nitrogen.This method provides a strategy for preparing highly efficient bimetallic ORR catalysts.