Graphene Production via Supercritical Fluid Reduction
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Solution Overview
Problem
Current methods for preparing graphene often involve hazardous reducing agents and result in impurities, leading to decreased electrical conductivity and inefficiencies in mass production.
Innovation Solution
A method using a mixed solution of graphite oxide, a solvent, a sulfur compound or nitrogen compound, and a reducing adjuvant under subcritical or supercritical conditions to produce graphene with low oxygen content and high carbon/oxygen weight ratio, effectively removing impurities and enhancing electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chemical oxidation and reduction method is used for mass production of graphene, then productivity and economical feasibility are improved, but harmful factors increase due to use of hazardous reducing agents (hydrazine) with high corrosiveness, explosiveness, and human toxicity
Solution Approach 1:
The patent converts the harmful oxidized state of graphite oxide into a beneficial reduced state by using water under subcritical or supercritical conditions as a reducing agent. This transforms the previously harmful chemical reduction process into a safe physical-chemical process where water acts as both solvent and reducing agent, eliminating hazardous chemicals while achieving the desired graphene product.
Solution Approach 2:
The patent changes the physical parameters of water (temperature and pressure) to subcritical or supercritical states to alter its chemical properties. By controlling temperature (200-400°C) and pressure (73-300 atm), water gains enhanced reducing capability and solubility, enabling it to effectively reduce graphite oxide without requiring hazardous chemical reducing agents.
2Manufacturing precision
If chemical reducing agents are used for deoxygenation of graphene oxide, then oxygen content is reduced, but impurities are introduced that decrease electrical conductivity
Solution Approach 1:
The patent eliminates the introduction of harmful impurities by replacing chemical reducing agents with subcritical or supercritical water. The water molecules physically penetrate and reduce the graphite oxide structure through hydrothermal reactions, removing oxygen functional groups without leaving behind harmful chemical residues that would compromise electrical conductivity.
Solution Approach 2:
Water serves as an intermediary substance that mediates the reduction process. It acts as both the reaction medium and the reducing agent, facilitating the removal of oxygen from graphite oxide through controlled hydrothermal treatment. This intermediary role allows water to transfer hydrogen atoms to the carbon structure while maintaining purity and avoiding contamination from external reducing agents.
3Ease of manufacture
If traditional exfoliation methods are used, then graphene can be produced, but production efficiency is low and impurities remain
Solution Approach 1:
The patent dramatically improves production efficiency by changing the physical state parameters of the reaction system to subcritical or supercritical conditions. This parameter change enables rapid reduction and exfoliation of graphite oxide into high-quality graphene with controlled layer thickness, achieving both high productivity and product quality simultaneously through continuous processing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves high-quality graphene with excellent electrical conductivity and thermal stability, suitable for various industrial applications by reducing oxygen content and impurities, and enabling continuous, economical, and low-risk production.
Implementation Method 1
forming the graphene by reacting the mixed solution under a subcritical condition or a supercritical condition of the solvent
Implementation Method 2
forming the graphene by reacting the mixed solution under a subcritical condition or a supercritical condition of the solvent
Implementation Method 3
reducing agents such as hydrazine, and the like, should be used for a deoxygenation reaction of graphene oxide
Implementation Method 4
chemical oxidation and reduction
Data Source
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AI summary
There are provided a graphene having an oxygen atom content in a predetermined range or less and a carbon/oxygen weight ratio in a specific range to show excellent electrical and thermal conductivity properties, and a barrier property, and a method and an apparatus for preparing the graphene having excellent electrical and thermal conductivity properties and a barrier property by using a subcritical-state fluid or a supercritical-state fluid. According to the method and the apparatus for preparing the graphene, impurities such as graphene oxide, and the like, may be effectively removed, such that uniformity of the graphene to be prepared may be increased, and therefore, the graphene which is highly applicable as materials throughout the industry may be mass-produced.