Abstract: Disclosed herein are composite materials and methods of making and use thereof. The composite materials comprise: a carbon nanotube and a plurality of ferrihydrite particles disposed on the carbon nanotube, the composite material comprising the plurality of ferrihydrite particles and the carbon nanotube in a weight ratio of from 5:95 to 95:5. The weight ratio can be selected such that the composite material has a desired balance between specific surface area and specific capacitance. Also disclosed herein are methods comprising: making a plurality of the composite materials, the weight ratio of the plurality of ferrihydrite particles and the carbon nanotube being different for each composite material; and determining and comparing the specific surface area and specific surface capacitance for the plurality of composite materials to determine the weight ratio at which the composite material has a desired balance between the specific surface area and the specific capacitance.