A supercapacitor electrode comprising a mixture of graphene sheets and humic acid, wherein humic acid occupies 0.1% to 99% by weight of the mixture and the graphene sheets are selected from a pristine graphene material having essentially zero % of non-carbon elements, or a non-pristine graphene material having 0.001% to 5% by weight of non-carbon elements wherein said non-pristine graphene is selected from graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, chemically functionalized graphene, or a combination thereof; and wherein said mixture has a specific surface area greater than 500 m2/g.