Porous Graphite – A Complete Guide

Porous graphite is a new type of carbon material and has attracted much attention in the field of materials science. It retains the characteristics of graphite conductivity and stability, and introduces the pore structure, which has better performance. And it has great potential in the fields of energy, environment, catalysis, and so on.

Preparation method of porous graphite

Template method

Template method is a key method for preparing porous graphite. Hard templates such as silica nanospheres and anodized aluminum are regular in shape and stable in structure. First, fill the carbon sources such as phenolic resin into the template gap. And after high temperature carbonization, the carbon source is converted into graphite, and then the template is removed with chemical reagents, leaving pores. The flexible template uses micelles formed by self-assembly of surfactants to guide the deposition of carbon sources. And the porous structure is obtained by heat treatment. The method can accurately control the pores and prepare highly ordered porous graphite. But the template removal is complicated and the cost is high.

Chemical Vapor Deposition (CVD)

Under the action of high temperature and catalyst, CVD decomposes methane, ethylene and other gaseous carbon sources. And carbon atoms are deposited on the substrate surface to generate graphite. The growth rate and pore structure of graphite can be controlled by adjusting gas flow, temperature, pressure and catalyst. The porous graphite prepared by this method has high crystallinity and tight bonding with substrate. It is suitable for semiconductor manufacturing and other fields. But the equipment is expensive, the preparation is complicated and the yield is low.

Activation Method

The activation method uses graphite powder, carbon fiber and other formed carbon materials as raw materials. Physical activation with high temperature water vapor, carbon dioxide etch carbon atoms to form pores. Chemical activation allows carbon materials to react with potassium hydroxide, phosphoric acid and other reagents at a lower temperature to create holes. Such as potassium hydroxide activation after washing to remove potassium salt to leave holes. This method is simple and low-cost, and can greatly improve the specific surface area and porosity. But it is difficult to accurately control the pore structure, and the pore size distribution is wide.

Microstructure and Properties

Pore structure analysis

The porous graphite has three kinds of pores: micropores, mesoporous pores and large pores. The micropore size is less than 2nm, providing a large specific surface area, which is conducive to small molecule adsorption. Mesoporous aperture 2-50nm, help material diffusion. Macropores with apertures greater than 50nm are the channels through which substances enter the interior. The pore size of porous graphite prepared by template method is uniform. And the multi-stage pore structure formed by activation method is taken into account the adsorption and transport efficiency. It plays a prominent role in the field of environment and energy.

Crystal structure characteristics

Porous graphite is based on the layered structure of graphite, carbon atoms are covalently bonded to form hexagonal planes. And the layers are maintained by van der Waals forces. The preparation of pores causes lattice defects and disordered arrangement, but gives the material special properties. For example, in lithium-ion batteries, these defects can provide more storage sites for lithium ions, accelerate ion embedding and release. And improve battery charging and discharging performance and cycle stability.

Surface chemical properties

Preparation process and post-treatment determine the surface chemical properties of porous graphite. In the process, functional groups such as hydroxyl and carboxyl groups are introduced to give the material chemical reaction activity. Such as the carboxyl group can react with alkaline substances. At the same time, these functional groups affect the hydrophilicity and dispersion of the material. In adsorption applications, regulating surface functional groups can achieve efficient adsorption of specific substances. Such as porous graphite containing amino acids can adsorb acidic gases.

Performance advantages of porous graphite

High specific surface area and adsorption properties

The porous graphite is filled with abundant pores, creating a very high specific surface area. Some of them can reach thousands of square meters per gram. This feature provides a large number of adsorption sites, showing a strong adsorption capacity for various molecules and ions in gases and liquids. Compared with the traditional adsorption materials, it has a larger adsorption capacity, faster speed. And it can efficiently purify the environment and solve the pollution problem.

Excellent electrical conductivity

Inheriting the intrinsic characteristics of graphite, porous graphite has excellent electrical conductivity. Its unique layered crystal structure builds an efficient channel for electron transport. And even if there are pores, it is difficult to hinder electron conduction, and the conductivity is still maintained at a high level. In the field of energy storage and conversion, this advantage is highlighted. It can quickly conduct electrons, reduce internal resistance, greatly improve charge and discharge efficiency and power density.

Good thermal stability

Thanks to the strong covalent bond between carbon atoms, porous graphite has excellent thermal stability. In the high temperature environment above 1000℃, the structure can still be maintained stable, and no obvious performance decline occurs. Thanks to its thermal stability, it plays an important role in many high temperature applications.

Applications of porous graphite

Energy storage and conversion

Lithium ion battery

In lithium-ion batteries, you can use it as a negative electrode material. Its rich pores can store more lithium ions, improve the specific capacity of the battery. The good conductivity speeds up charge and discharge, eases the change of charge and discharge volume, and extends the service life of the battery.

Supercapacitors

You can use it for supercapacitor electrode, its high specific surface area can form double electric layer capacitor. The excellent conductivity achieves fast charge transfer, so that the supercapacitor has high power density, fast charge and discharge characteristics.

Environmental field

Wastewater treatment

Porous graphite wastewater treatment, relying on high specific surface area adsorption of organic pollutants, heavy metal ions. And it also supports catalysts, catalytic degradation of organic pollutants, to achieve harmless wastewater treatment, purification of water quality.

Air purification

With high adsorption performance, it can absorb harmful substances such as sulfur dioxide, nitrogen oxides and volatile organic compounds in the air. And you can make it into air purification filters and coatings to improve air quality.

Catalysis

Catalyst carrier

Porous graphite as a catalyst carrier, high specific surface area can disperse the active substance. Good stability ensures its structural stability in the catalytic reaction, improves catalyst activity and selectivity, widely used in chemical reactions.

Direct participation in catalytic reactions

Its surface defects and functional groups have catalytic activity, you can use it as non-metallic catalyst in organic synthesis reaction. The reaction conditions are mild, high selectivity, help green chemical synthesis, reduce pollution.

Other areas

Semiconductor manufacturing

With its good thermal stability and conductivity, you can use it as a high-temperature furnace component and heat dissipation material. To ensure process stability, effectively solve the chip heat dissipation problem, and improve device performance.

Biomedical Science

Porous graphite with good biocompatibility can be used as a drug carrier to achieve controlled drug release. And you can also use it to prepare biosensors, detect biomolecules, and assist in early diagnosis and treatment of diseases.

Conclusions

As a new type of carbon material, porous graphite has unique structure and excellent performance. A variety of preparation methods can regulate its structural properties to meet multiple needs. It plays a significant role in many fields. And with the development of technology, it is expected to provide key material support for solving global problems in the future.