Carbon-based materials are widely used in many fields such as energy storage, environmental science, and materials chemistry. In the past few decades, many scholars at home and abroad have successfully developed a rich variety of emerging carbon-based materials, such as biochar, graphene, graphene oxide (GO), carbon nanotubes, carbon nanofibers, carbon spheres, carbon aerogels, nitrogen-doped carbon and graphite phase carbon nitride. Aerogel is a kind of new solid material with ultra-fine porous structure and low density. Since its birth in 1931, it has always attracted wide attention. With the continuous progress of time, researchers continue to explore and optimize the preparation methods of aerogel, from the initial inorganic silica aerogel gradually developed to organic aerogel, and then extended to carbon aerogel, and correspondingly, the application range of aerogel is also continuing to expand.
Carbon-based aerogels are a new type of nano-porous carbon materials obtained by carbonization at high temperature in an inert gas environment, using organic aerogels as precursors. They have the dual characteristics of both aerogels and carbon-based materials. Due to its low density, high specific surface area and high porosity, carbon-based aerogel has been widely used in energy storage, adsorption, sensor, electromagnetic shielding and absorption.
Image source:Journal of Colloid and Interface Science
Classification of carbon-based aerogels：
Based on the difference of raw material sources, carbon aerogels can be roughly divided into three categories: graphite-based carbon aerogels, organic carbon aerogels and carbon composite aerogels.
For graphite-based carbon aerogels, such as graphene aerogels and carbon nanotube aerogels, graphite-carbon materials are directly combined into three-dimensional aerogel structures using appropriate assembly processes. Due to their high electrical conductivity, these carbon aerogel materials are widely used in a variety of electronic devices and sensors.
The precursor material of organic carbon aerogel belongs to organic matter, which is transformed into carbon material after high temperature carbonization process, and then three-dimensional porous structure is constructed with the help of assembly process. These carbon-based aerogels can be subdivided into biomass carbon aerogels and polymer-based carbon aerogels. Because of their excellent adsorption properties and unique structural characteristics, they have broad application and development potential in the fields of environmental protection and energy.
Carbon composite aerogel is a very important development trend in carbon-based aerogel field in recent years. By introducing organic groups or polymer, the ratio between components can be adjusted and controlled, and then the problems of single component carbon-based aerogel materials such as greater brittleness, easy moisture, poor flexibility and so on can be optimized. While maintaining excellent properties, carbon composite aerogels achieve functional complementarity between different materials, which opens up a broader space for the application of carbon-based aerogels.
Preparation of carbon-based aerogel：
The preparation of carbon-based aerogel usually includes the following three steps: (1) precursor solation, sol gelation and aging; ② The gel dries to become aerogel; ③ Carbonization of aerogel to obtain carbon-based aerogel. Carbon-based aerogel has shown good performance in many applications, but the complex preparation process, high cost and low yield limit its practical application. The preparation methods of carbon-based aerogel materials mainly include sol-gel method, hydrothermal method, chemical vapor deposition method and ice template method.
Application of carbon-based aerogel：
Carbon-based aerogel is a kind of light, porous, amorphous carbon material with nanoporous structure. Carbon-based aerogel has important application value in the key fields of electrochemical energy storage, catalyst and its carrier, national defense and military industry and environmental protection.
1.Thermal insulation for hot batteries and supercapacitors
In energy storage equipment, temperature has a great impact on its performance and lifetime. Aerogel can be used as a thermal insulation material for hot batteries and supercapacitors, preventing heat from being transferred too quickly inside the battery or capacitor, and maintaining the stability of the operating temperature of the equipment, thereby improving the performance and safety of the equipment.
2.Sound-absorbing material
The porous structure of aerogel makes it have good sound-absorbing properties. When sound waves propagate in the pores of aerogel, they will be reflected and scattered many times, so that the sound energy will continue to decay. In concert halls, recording studios and other places with high acoustic environment requirements, aerogel can be used to manufacture sound absorbing panels, effectively reducing the indoor reverberation time and improving the clarity of sound.
3.Catalyst support
The high specific surface area of aerogel provides a large number of loading sites for catalyst. In environmental catalytic reactions, such as catalytic purification of automobile exhaust gas, catalytic oxidation of industrial waste gas, etc., loading the catalyst on the aerogel carrier can improve the dispersion and activity of the catalyst, so as to catalyze the conversion of harmful substances more effectively and reduce the emission of pollutants.
4.Packaging materials for electronic devices
Aerogels have good electrical insulation properties and low dielectric constant, and can be used as packaging materials for electronic devices. In electronic devices such as integrated circuits and chips, aerogel packaging can protect electronic components from environmental factors such as moisture and dust, while its low dielectric constant helps reduce delays and losses during signal transmission.
image source：RSC Advances