Graphene coatings for corrosion resistance of nickel and copper in acidic, alkaline and neutral environments

•Multilayer graphene coating provides robust and similar corrosion resistance to Ni irrespective of the aggressiveness of the environment.•Improvement in corrosion resistance of bare Ni due to multilayer graphene coating is greatest in the most aggressive environment of 0.5 M H2SO4.•Improvement in corrosion resistance of bare Ni due to multilayer graphene coating is least in 0.5 M NaOH because Ni develops a robust passive layer.•The improvement in corrosion resistance of bare Cu is limited because Cu develops only 1–2 layers of graphene.