Graphene Powder Defect Repair via Supercritical Fluid Impregnation
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Solution Overview
Problem
Current methods for repairing graphene defects, such as wet chemical reactions, are limited by room temperature processing, difficulty in penetrating multilayer graphene, complexity, and environmental concerns, which hinder complete defect repair and increase production costs.
Innovation Solution
A method involving a composite fluid with a reactive compound and supercritical fluid is used to impregnate graphene powder in a reactor, utilizing the solubility and diffusion of the supercritical fluid to passivate and repair defects, with the reactive compound forming bonds like C—H, C—O, or C—Si, and using molecular sieves for separation, thereby reducing defects and improving conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet chemical reaction method is used to repair graphene defects, then defect repair is attempted, but the process is limited by room temperature processing, cannot penetrate multilayer graphene, and produces waste liquid
Solution Approach 1:
The patent changes the temperature and pressure parameters by using supercritical fluid (typically CO2 at above 31°C and 73 atm), transforming the fluid into a supercritical state that can penetrate multilayer graphene effectively. This parameter change enables the reactive compound to reach and repair defects in multilayer structures while avoiding the waste liquid problem of conventional wet chemical methods, as the supercritical fluid can be easily separated and recycled.
2Reliability
If wet chemical reaction method is used at room temperature, then defect passivation is attempted, but the penetration ability into multilayer graphene is insufficient
Solution Approach 1:
The patent applies parameter changes by elevating temperature and pressure to achieve supercritical fluid state, which dramatically improves penetration ability into multilayer graphene while maintaining effective defect passivation. The supercritical fluid's unique properties (high diffusivity, low viscosity, and solvent power) enable it to penetrate deep into stacked graphene layers, delivering reactive compounds to repair defects throughout the multilayer structure.
Solution Approach 2:
The patent utilizes phase transition by transforming the fluid (typically CO2) into a supercritical phase through temperature and pressure control. This phase transition creates a fluid state that combines properties of both gas (high penetration and diffusivity) and liquid (solvent power and reactivity), enabling effective delivery of reactive compounds into multilayer graphene for comprehensive defect repair.
3Productivity
If conventional preparation methods are used, then graphene is produced, but many defects are created due to covalent bond cleavage
Solution Approach 1:
The patent applies preliminary action by performing defect repair treatment on graphene after its preparation but before final application. The process involves: (1) preparing graphene using conventional methods, (2) treating it with supercritical fluid containing reactive compounds to repair defects, and (3) separating the supercritical fluid to obtain high-quality graphene. This preliminary repair step eliminates defects created during preparation without requiring changes to the original high-productivity preparation methods.
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
This method effectively reduces graphene defects, increases the composition content, and decreases the number of layers, providing graphene with enhanced thermal and electrical conductivity while maintaining a simple, low-cost process without pollution, offering wide application prospects.
Implementation Method 1
utilizing the solubility and diffusion of the supercritical fluid to passivate and repair defects
Implementation Method 2
a composite fluid having a reactive compound and a supercritical fluid is used to impregnate graphene powder
Implementation Method 3
separating the composite fluid and the graphene powder, and adsorbing the graphene powder retained in the composite fluid by a molecular sieve
Data Source
AI summary
The present disclosure provides a method for repairing defect of graphene, including: firstly introducing a composite fluid containing a reactive compound and a supercritical fluid to a reactor where the graphene powder has been placed, and impregnating the graphene powder with the composite fluid to passivate and repair the defect of graphene, wherein the reactive compound includes carbon, hydrogen, nitrogen, silicon or oxygen element; and separating the composite fluid from the graphene powder, simultaneously using molecular sieves to absorb the graphene from the composite fluid. The present disclosure further provides the graphene powder prepared by the method above. With the method of the present disclosure, it effectively reduces the ratio of the defect of the graphene, increases the content of the graphene, and has less-layer graphene with high thermal conductivity and electrical conductivity.