Growth of carbonaceous nanomaterials over stainless steel foams. Effect of activation temperature

•Stainless steel foams are suitable catalytic substrates to develop coatings of carbonaceous nanomaterials, like CNFs or graphene.•The oxidation temperature of the metallic foam affects to the type and morphology of the carbonaceous nanomaterials obtained.•The maximum productivity of CNMs, 17mgC/g foam.min, is obtained after oxidation, reduction and reaction at 800°C.•The highest adherence of the carbonaceous deposits to the metallic foam is obtained after oxidation, reduction and reaction at 800°C.•Elevated reduction temperatures, ca. 900°C, cause a loss of productivity due to the sintering of Fe and Ni nanoparticles exposed at the surface of the foam.