The present invention provides an adhesive comprising graphene oxide including at an epoxy group, a hydroxyl group or a carboxylic acid group; and an alkoxysilane compound including an amine group, an epoxy group, a carboxylic acid group, a hydroxyl group, or a thiol group. More specifically the adhesive may be used for bonding a polyurethane elastomer to an aluminum material, in which a silane compound and graphene oxide are applied to improve adhesive strength, compared to adhesives including the silane compound only. In addition, during a separation process for recycling after use, the aluminum material and polyurethane can be easily separated from each other by polyurethane pyrolysis through rapid heating due to microwave absorption properties of graphene oxide.