▎ 摘　　要

NOVELTY - Preparing large-size graphene sheet with high mechanical strength involves dissolving potassium persulfate and phosphorus pentoxide in concentrated sulfuric acid for 0.5 hours to obtain dispersed solution. The graphite is added with obtained dispersion solution at 78-82 degrees C with stirring for 4.5 hours, then cooled to room temperature and then diluted using de-ionized water. The supernatant is removed, then filtered the precipitate with 0.2 millimeter filter for removing impurities, dried for 12 hours in vacuum drying box and then grinding to obtain oxide precipitate. USE - Method for preparing large-size graphene sheet with high mechanical strength (claimed). ADVANTAGE - The method enables to prepare large-size graphene sheet with high mechanical strength in simple and safe manner. The product has good application prospect. DETAILED DESCRIPTION - Preparing large-size graphene sheet with high mechanical strength involves dissolving potassium persulfate and phosphorus pentoxide in concentrated sulfuric acid for 0.5 hours to obtain dispersed solution. The graphite is added with obtained dispersion solution at 78-82 degrees C with stirring for 4.5 hours, then cooled to room temperature and then diluted using de-ionized water. The supernatant is removed, then filtered the precipitate with 0.2 millimeter filter for removing impurities, dried for 12 hours in vacuum drying box and then grinding to obtain oxide precipitate. The 120 mL of concentrated sulfuric acid is added with stirring and temperature is controlled at 4-6 degrees C. The 15 g potassium permanganate is ground into powder, then added concentrated sulfuric acid at 4-6 degrees C, then the temperature is controlled at 33-37 degrees C with stirring for 2 hours. The 250 mL deionized water is added to dilute the solution with stirring for 2 hours, where diluting temperature is controlled at 14-18 degrees C. The 0.7 L of de-ionized water and 30% hydrogen peroxide are added. The mixture is stirred at room temperature for 2 hours. The reaction produces bubbles and the color changes from brown to bright yellow. The mixture solution is allowed to stand overnight. The supernatant is removed, then diluted with 1 L of deionized water, and the diluted solution is dispensed into 35-50 mL centrifuge tubes and centrifuged at a speed of 10,000 revolutions/minutes for 10 minutes. The precipitate A is put into the beaker, washed the precipitate A and packed into 30-50 mL centrifuge tube. The packed precipitate A is centrifuged at a speed of 10000 revolutions per minutes for 10 minutes, then removed the supernatant and centrifuged to obtain precipitate B'. The obtained precipitate B' is washed with deionized water. The washed precipitate B' is put into 30-50 mL centrifuge tube, then Centrifuged at a speed of 10,000 revolutions/minutes for 10 minutes to obtain precipitate C'. The dispersion solution of the graphene oxide is mixed with 5 moles/litres sodiumchloride to precipitate the salt, then dissolved the precipitate overnight and then removed the supernatant to obtain large size graphene sheet.