Custom‐Built Graphene Acoustic‐Absorbing Aerogel for Audio Signal Recognition

Abstract

Porous acoustic‐absorbing materials currently used to solve noise pollution mainly include polyurethane composite materials and porous fibers which are dedicated to achieving good noise reduction effects in a wide frequency range. Nevertheless, traditional porous acoustic‐absorbing materials face irreparable defects as required by the multifunction and high energy efficiency. The reason is nothing more than the internal microstructure of conventional acoustic‐absorbing materials is difficult to be precisely controlled by macroscopic operations, resulting in poor mass transfer capability and low energy conversion efficiency. In this work, by customized design of controlled mechanical foaming and atmospheric drying technique, a custom‐built graphene aerogel (cGA) as acoustic‐absorbing material with an acoustic absorption coefficient approaching 100% is prepared, which can efficiently absorb noise at an assigned frequency (2000–6000 Hz range) according to individual needs. Through simple stacking, cGAs expand from single‐frequency absorption to multi‐frequency high‐efficiency absorption. What is more significant is that a single aerogel has electrical signal responses of different intensities to sounds of different frequencies, which allows to build the aerogel into an acoustic detector to convert noise signals into electrical signals and realize the goal of sound fingerprint detection.

The promising solar‐powered water purification based on graphene functional architectures

“…Therefore, the studies of graphene assemblies have attracted much attention in the past few years. For example, as shown in Figure 1D, three-dimensional (3D) graphene foams with massive channels and porous structures can be obtained from graphene oxide dispersion by hydrothermal methods, 25,26 template-assisted reduction assembly, [27][28][29] freeze-drying process, 30 in situ growth on 3D metal templates, 31 and even natural drying. 32,33 Two-dimensional (2D) graphene films can be synthesized via filtration, 34,35 evaporation induced self-assembly method, 36 and so on.…”

From Materials to Devices: Graphene toward Practical Applications

“…a peak value, which often corresponds to the natural frequency of the structure. Li et al [123] studied the acoustic absorption curve of partial rGO hydrogels, and concluded that the absorbing performance was greatly affected by rGO concentration, and the peak of curve shifted toward low frequency as the rGO con-centration increased (Figure 10a). In order to overcome the problem that traditional sound-absorbing materials only have good sound-absorbing effect in a certain frequency domain and low energy conversion effect, they compressed rGO hydrogels and built a superimposed structure stacked by hydrogels with The process of compressing custom-built cGA to obtain aerogel with the same size and different graphene concentration.…”

“…Reproduced with permission. [ 123 ] Copyright 2021, Wiley‐VCH. d) Schematic diagram of microwave absorption and attenuation.…”

“…c) The acoustic absorption coefficient-frequency curve of quintuple-superimposed cGA. Reproduced with permission [123]. Copyright 2021, Wiley-VCH.…”