1. Silica aerogels
The process of preparing silicon aerogel is roughly as follows: the raw material is water glass, which is soluble silicate; Add a suitable amount of condensing substance (just like adding a little alum to a water tank); A solid framework is formed in the solution, but it also contains salt substances; Rinse the salt with a large amount of ionized water; Then use the method of freeze-drying with negative pressure to remove the solution; Post processing is also required, which includes a series of steps such as aging and cracking prevention; Finally, the aerogel with unique performance is obtained.
Silicon aerogel is a solid material. Its basic characteristics are that it is porous, disordered, has a continuous network structure of nanometer scale, and the porosity of the framework is high; Large specific surface area; The frame has elasticity and can rebound after compression; The overall density is very low, with air accounting for over 99.8% of the total; Like glass, its composition is silicon dioxide, but silicon aerogel is the lightest solid in the world.
Silicon aerogel is the solid material with the best thermal insulation performance at present. In the civil field, the thermal insulation of glass, walls, refrigerators and pipes is very effective; Especially in aviation, aerospace, and military, this good insulation material is increasingly being used.
Silicon aerogel is the best structure for catalyst because of its huge porosity and specific surface area, but its thermal insulation hinders the catalytic process; Scientific workers came up with a way to mix titanium oxide solution and silicon dioxide solution before making aerogel; Then the aerogel catalyst containing "titanium oxide - silicon dioxide" is prepared. Inspired by this, people can make a variety of aerogel catalysts.
Silicone aerogel has a very good sound insulation effect. Because of its small gap and its high temperature resistance, aging resistance and corrosion resistance, it can be used as a sound insulation layer between glasses and as a sound insulation device of acoustic instruments.
Silicon aerogel has a good effect as the substrate of integrated circuit because of its good insulation, relatively high breakdown resistance voltage, thermal expansion coefficient close to that of silicon material, and good thermal stability. It will replace the previously common substrate materials.
The unique properties of silicon aerogels have aroused people's interest in basic research. Scientists hope that different aerogels can solve different application purposes.


2、 Carbon aerogel
Inspired by the production method of silicon aerogel, people use an organic material that can be carbonized and configured into
The solution of mechanical materials is added with coagulant to make organic aerogel, which is carbonized at high temperature in inert gas to obtain carbon aerogel.
This is just an intuitive method for making carbon aerogel. Now there are other methods that can be mass produced.
Carbon aerogel is a nano scale three-dimensional network structure. The network structure is elastic, with a very large specific surface area and a particularly light overall weight. It is a new type of carbon material.
Carbon aerogels are aerogels and carbonaceous aerogels, which determine their numerous applications. Here are a few examples.
1. Used as a fuel cell electrocatalyst carrier or electrocatalyst
Carbon aerogels and their composites are mainly used as carriers or directly as electrocatalysts in fuel cells because of their large specific surface area, stable electrochemical performance and conductivity.
2. Used as a negative electrode material for lead-acid batteries
The introduction of carbon gas gel (called lead carbon battery) into the negative electrode of lead-acid battery can reduce the sulfation of the negative electrode, enhance the charge acceptance ability, reduce the charging voltage, thus improving the efficiency, reducing the corrosion of the positive plate, extending the cycle life, and improving the energy storage performance.
3. Used as a positive electrode material for lithium-ion batteries
Adding carbon aerogel material to the positive electrode of the lithium ion battery can form a capacitive lithium ion battery
By significantly reducing energy density, its specific power and lifespan can be improved.
4. Used as an environmentally friendly treatment material
The existing environmental protection technologies generally use ion exchange, heating evaporation, and reverse osmosis methods to treat metal ions in wastewater; In contrast, carbon aerogel has many advantages in electro adsorption removal of metal ions in solution, including regeneration, reduction of secondary pollution and energy saving; Ultra high specific surface area, ultra-low density, good chemical inertness, corrosion resistance, and high compression mechanical properties can be used as selective oil-water separation adsorbents by modifying surface functional groups, and can be reused through distillation or combustion. Macroporous, mesoporous and microporous structures can produce strong thermionic effect and improve photothermal conversion efficiency. Carbon aerogels can be used as materials for seawater desalination, hard water softening and sewage treatment.
5. Used as a catalyst carrier
The network structure with high specific surface area, high porosity, low density and good stability is one of the best materials for catalyst support. As long as catalyst nanoparticles are effectively combined in carbon aerogel, blocky catalyst materials can be made.
6. Used as a biomedical material
With high porosity, biocompatibility and biodegradability, carbon aerogel has a wide range of applications in the medical field, such as diagnostic agents, artificial tissues, artificial organs, organ components, etc. Especially suitable for drug controlled release systems, it can achieve high drug loading capacity.
7. Used as a hydrogen storage material
Carbon aerogels have high specific surface area, low density, continuous network structure, small pore size and communication with the outside world. They have excellent hydrogen absorption and desorption properties under low pressure conditions, and are currently one of the potential best carbon based nano solid hydrogen storage materials.
Military and aerospace fields
Compared with traditional thermal insulation materials, nano porous aerogel super thermal insulation materials can be used with lighter weight and smaller
The volume achieves equivalent insulation effect. This characteristic gives it a significant advantage in the fields of aviation and aerospace applications. If used as insulation material for aircraft engines, it not only provides excellent insulation but also reduces the weight of the engine. As a super insulation material for outer space exploration and transportation vehicles, it also has great application prospects.
Intuitively, the thermal insulation performance of carbon aerogel is very good. It is assumed that the combination of silicon aerogel and carbon aerogel gel can be used as thermal insulation materials for refrigerators and other refrigeration equipment, and the effect must be very good.


3、 Graphene aerogel
If you want to use graphene fragments to make aerogels, you can use the usual method, that is, "solution" - "condensation" - "curing", but this method cannot guarantee the shape of the material.
Technology workers have come up with a simple production method: 1) Mix graphene powder, carbon nanotubes, and deionized water into a certain concentration of aqueous solution; Uniform ultrasonic oscillation; 2) Graphene organic hydrogel was prepared at high temperature; 3) Soaking the graphene organic hydrogel in ammonia water; 4) Low temperature and low pressure drying. In this way, graphene aerogels with high elasticity are obtained.
This method is simple and feasible. By changing the container, any shape of "carbon sponge" can be obtained, which can be manufactured on a large scale.
Graphene aerogel has high elasticity, and can still be recovered after 80% compression, and its density is only 1/6 of that of air. In addition to the characteristics of aerogel, especially large specific surface area and light specific gravity, it also has the characteristics of carbon and graphene texture. So it will bring numerous applications.
Graphene aerogel has super fast and high adsorption capacity for organic solvents, and is the material with the highest oil absorption capacity reported so far. And it only absorbs oil without absorbing water. If they are scattered on the sea surface, they can quickly absorb the oil leakage, then squeeze out the oil, and the materials can be recycled. Each gram of graphene aerogel can absorb 900 grams of gasoline, which is an oil absorption device for dealing with marine pollution.
Graphene aerogel can be used as a new type of gas filter material and liquid filter material.
Graphene aerogel can be used as the electrode of water electrolysis, the electrode of caustic soda electrolysis, and the electrode of hydrogen fuel cell, and the effect must be very good.
Graphene aerogel must be very effective as a supercapacitor.
Graphene aerogel must be very good as a carbonaceous catalyst material.
If the graphene aerogel is filled with appropriate electrolyte, it can certainly be made into a new type of rechargeable battery. It must have excellent characteristics such as large storage capacity, small internal resistance, light weight, fast charging and discharging energy, and can be repeatedly used.
The graphene aerogel is made into a thin layer, which can make cold proof clothes from the perspective of heat insulation; Improving its impact resistance can make it a bulletproof vest; There will definitely be good results.