Preparation and Application of Porous Graphene

Release time:

2019-05-22

Graphene is a two-dimensional carbon material composed of a single layer of sp2 hybridized carbon atoms arranged in a hexagonal pattern. It has advantages such as a large theoretical specific surface area, high intrinsic carrier mobility, high thermal conductivity, and ultra-high electrical conductivity at room temperature. Due to its unique structure and properties, graphene has gradually become one of the attractive application materials. However, graphene also has its shortcomings. In the field of digital electronics, due to the lack of a bandgap between the electrons in graphene, it is difficult to stop data transmission once it has started. The solution is to create a bandgap by perforating the surface of graphene or integrating two-dimensional graphene to construct a specific three-dimensional structure, forming a porous structure. Preparation Methods for Porous Graphene Template Method The template method can be divided into hard template and soft template methods based on the composition and characteristics of the template. Hard Template Method The preparation of porous graphene materials using the hard template method mainly involves four aspects: (1) preparing the hard template; (2) functionalizing/modifying the template surface to obtain suitable surface properties; (3) coating graphene or its derivatives, such as graphene oxide, onto the template using various methods; (4) selectively removing the template. The hard template method also has many drawbacks, such as relatively low yield, inability to achieve high production, significant limitations when using multi-step synthesis processes, and insufficient structural integrity during template removal. Soft Template Method The soft template method involves a self-assembly reaction between carbon precursors and soft templates, resulting in porous graphene through high-temperature carbonization and polymerization. The pore structure mainly depends on the synthesis conditions, such as the ratio of reactants, type of solvent, and reaction temperature. This method can be directly used to synthesize mesoporous or macroporous graphene materials. Compared to hard templates, soft templates essentially involve synthesis at the molecular level, constructing porous structures while utilizing chemical bonds or hydrophilic/hydrophobic interactions. In the process of preparing porous graphene materials using the soft template method, the chemical reaction between the template and surfactants plays a crucial role. Template-Free Method The template-free method includes etching, solvothermal, and chemical vapor deposition methods. Etching Method The etching method utilizes a chemical reaction between the etchant and graphene, causing the carbon atoms on the surface of graphene to be etched away, leaving behind a pore structure. This method has significant selectivity for material etching, meaning that etching stops immediately after completion, without damaging the remaining material layers. Solvothermal Method The solvothermal method involves using water or organic solvents as the reaction system in a specific high-pressure reaction vessel, heating it to the critical temperature, and synthesizing materials in a high-pressure reaction system. This method greatly reduces environmental pollution, and the porous graphene materials produced have the advantage of controllable pore size. Chemical Vapor Deposition Method The main process of preparing porous graphene materials using the chemical vapor deposition method involves introducing carbon-containing gases such as methane and acetylene, allowing the gaseous carbon source to deposit onto the surface of a solid substrate to produce graphene, and then gradually heating in a protective gas to obtain porous graphene materials. This method is simple to operate, allows for large-scale production, and the resulting porous graphene materials have a complete structure and excellent electrical conductivity. Applications of Porous Graphene and Its Composites Electrode Materials Using porous graphene or composite materials as electrode materials, their highly interconnected structure greatly facilitates the rapid transport of ions, resulting in high capacity and power characteristics. Environmental Adsorption Materials Porous graphene has a rich pore structure, and due to differences in preparation methods, it contains many defects on the surface, making it easier to introduce different functional groups. Porous graphene and its composites have numerous applications in oil/water separation, metal ion adsorption, and dye molecule removal. Separation Field Through model establishment and computer simulation, it has been found that porous graphene has high permeability and selectivity for gas molecules such as hydrogen (H2), nitrogen (N2), and hydrogen sulfide (H2S), effectively separating mixed gases such as H2/CH4, CO2/N2, and H2S/CH4. References: Wu Pengbo, Wang Chengjun, et al. Research Progress on the Preparation of Porous Graphene and Its Nanocomposites Zeng Yang, et al. Research Progress on the Preparation of Porous Graphene Materials Shi Peng, Hou Zhaoxia, et al. Research Progress on Porous Graphene and Its Composites

Key words:

Porous, graphite, template, material, method, preparation, having, structure, etching