▎ 摘　　要

NOVELTY - Preparation of closed-cell graphene oxide sponge involves preparing graphene oxide by adding graphite to sulfuric acid, adding potassium permanganate, stirring, pouring distilled water, adding diluted hydrogen peroxide, sonicating, centrifuging, obtaining centrifugal solid, washing with water, and drying; preparing graphene oxide emulsion by adding graphene oxide powder into deionized water, sonicating, adding polyvinyl alcohol, stirring, placing in water bath, adding sodium chloride and diphenyl ether, and stirring to obtain graphene oxide emulsion; and freeze-drying, and vacuum drying. USE - Method for preparing closed-cell graphene oxide sponge (claimed) used for heat insulation material, marine sound absorbing material and hydrophobic material. ADVANTAGE - The method is simple and environment-friendly. DETAILED DESCRIPTION - Preparation of closed-cell graphene oxide sponge comprises: (A) preparing graphene oxide by adding natural graphite to 98% concentrated sulfuric acid, stirring at 300-400 revolutions/minute (rpm) for 10-40 minutes, adding 4-6 times potassium permanganate, stirring at 300-400 rpm for 2-2.5 hours, placing in ice bath at 30-40 degrees C, stirring at 300-400 rpm for 30-60 minutes, transferring to constant temperature water bath at 80 degrees C, stirring at 300-400 rpm, heating to 80 degrees C, pouring distilled water, dividing into 46 times, stirring at 300-400 rpm for 15-20 minutes, diluting with distilled water, adding diluted hydrogen peroxide, sonicating for 1-2 hours, centrifuging at 8000 rpm for 10 minutes, obtaining centrifugal solid, washing solid with distilled water until pH is 5-6, and drying at 60 degrees C for 7-8 hours to obtain graphene oxide powder; (B) preparing graphene oxide emulsion by adding graphene oxide powder into deionized water, sonicating for 1-2 hours, adding polyvinyl alcohol, stirring at 90 degrees C and 1000-1800 rpm for 20-30 minutes, placing in water bath at 40 degrees C, adding sodium chloride and diphenyl ether, and stirring at 8000-20000 rpm for 1 hour to obtain graphene oxide emulsion; and (C) freeze-drying at - 60 degrees C for 30 minutes, freeze-drying at - 60 degrees C for 3 days, obtaining lyophilized oxidized graphene block, and vacuum drying at 80 degrees C for 24 hours.