Structure-property relationship of graphene coupled metal (Ni, Co, Fe) (oxy)hydroxides for efficient electrochemical evolution of oxygen

•A series of 16 graphene coupled mixed-metal (oxy)hydroxides (Ni, Co, Fe) were prepared.•Iron incorporation induces increased d-spacing between nanosheets and ultra-small particle size.•The trend in Tafel slopes is related to the abundance of surface adsorbed hydroxyl groups.•Electronic structure and free energy change enhance the energetics for OER.