▎ 摘　　要

NOVELTY - Preparing graphene aerogel involves stirring and foaming the mixed solution of graphene oxide, reducing agent and foaming agent, so that the volume after foaming is 1.5-2.5 times the volume before foaming. The foamed mixture is put into the mold and heated at 50-90 degrees C to reduce it, and when the mixture turns into a black block and separates from the inner wall of the mold, added a volume not less than the volume of the black block to the mold. The heating and reduction reaction is continued for 8-10 hours, then freeze at (-20)-(-10) degrees C, and then thawn below 50 degrees C to obtain partially reduced graphene oxide hydrogel. The partially reduced graphene oxide hydrogel is mechanically compressed according to the required degree of compression, and then dried under 60 degrees C, and subjected to annealing treatment at 180-220 degrees C for not less than 4 hours to obtain the graphene aerogel. USE - Method for preparing graphene aerogel for sound-absorbing material and for acoustic identification device including an audio signal generator, a signal amplifier, the graphene aerogel, an insulating substrate, an electrochemical workstation, and a computer (all claimed). ADVANTAGE - The method by changing the thickness and compression degree of the graphene aerogel, makes possible to achieve high-efficiency noise absorption in any single frequency band within a wide frequency range, simple stacking and combination of graphene aerogels of different thicknesses and compression levels can achieve high-efficiency noise absorption in multiple frequency bands in a wide frequency range. The graphene aerogel can also be applied to an acoustic recognition device to realize the recognition of audio in a specific frequency band. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a sound-absorbing material is composed of N pieces of graphene aerogels, where the thickness of the N pieces of graphene aerogel is the same but the degree of compression is different, and sound-absorbing material exhibits N significant sound absorption peaks in a wide frequency band that requires sound absorption to achieve multi-frequency sound absorption, and N is an integer greater than or equal to 2.