Preparation method and application of bimetal organic framework composite material

The invention provides a preparation method of a bimetal organic framework composite material. According to the preparation method, the methanol solution of 2-methylimidazole is added into a zinc salt-containing solvent, and the methanol solution and the zinc salt-containing solvent are stirred uniformly, an obtained mixed solution stands still, so that ZIF-8 can be obtained; the methanol solutionof 2-methylimidazole is added into a solvent containing a proper amount of ZIF-8 and cobalt salt, and the methanol solution and the solvent are uniformly stirred, and an obtained mixed solution stands still, so that a bimetal organic framework precursor ZIF-8@ZIF-67 is obtained; the precursor is transferred into a tubular furnace so as to be subjected to high-temperature annealing, and porous carbon of a core-shell structure is obtained through derivation; the porous carbon material is mixed with PDDA, an obtained mixture is stirred, and the mixture is compounded with graphene oxide; and an obtained product is subjec