A semiconducting graphene structure may include a graphene material and a graphene-lattice matching material over at least a portion of the graphene material, wherein the graphene-lattice matching material has a lattice constant within about ±5% of a multiple of the lattice constant or bond length of the graphene material. The semiconducting graphene structure may have an energy band gap of at least about 0.5 eV. A method of modifying an energy band gap of a graphene material may include forming a graphene-lattice matching material over at least a portion of a graphene material, the graphene-lattice matching material having a lattice constant within about ±5% of a multiple of the lattice constant or bond length of the graphene material.