TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Component: The intercalation compound comprises alkali metal, halogen, metal halide, organic compound, and/or acidic compound. The intercalation compound comprises lithium, sodium, potassium, rubidium, cesium, fluorine, chlorine, bromine, iodine, iodine bromide, iodine chloride, arsenic fluoride, iron chloride, nickel chloride, cobalt chloride, pentacene, tetracene, anthracene, 9,10-dichloroanthracene, 9,10-dibromoanthracene, acetic acid, nitric acid, hydrochloric acid, and/or sulfuric acid. The graphitizing catalyst comprises nickel, cobalt, iron, platinum, gold, aluminum, chromium, copper, magnesium, manganese, molybdenum, rhodium, silicon, tantalum, titanium, tungsten, uranium, vanadium, and/or zirconium.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The graphene sheet is formed by preparing a substrate having a graphitizing catalyst disposed on surface(s) of the substrate; contacting a carbonaceous material with the substrate on which the graphitizing catalyst is disposed; and heat treating the carbonaceous material and the graphitizing catalyst in an inert or a reducing atmosphere to form graphene. The method further comprises removing the graphitizing catalyst by acid treatment after the heat treatment. The intercalation compound comprises alkali metal(s), halogen, metal halide, organic compound, and/or acidic compound.    TECHNOLOGY FOCUS - POLYMERS - Preferred Component: The carbonaceous material is carbon-containing polymer, gaseous carbonaceous material, and/or liquid carbonaceous material. EXAMPLE - A graphene sheet was disposed in a first chamber, and potassium (0.1 g) was disposed in the second chamber. Then, the two chambers were sealed by heating both ends of the quartz reactor. The first chamber was heated at 250 degrees C, and the second chamber was heated at 300 degrees C. After these temperatures were maintained for 48 hours, the second chamber was cooled, and then the first chamber was cooled to prepare a graphene sheet including potassium layers. A single unit layer of graphene was identified between the potassium layers by X-ray diffraction. The transmittance of the graphene sheet including the potassium was 85%.