High Functionalization Density Graphene via Electrochemical Exfoliation
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Solution Overview
Problem
It is challenging to obtain fully exfoliated, unaggregated graphene with desirable chemical functionalization for various applications, as existing methods often result in aggregated materials with low functionalization densities.
Innovation Solution
A method involving the application of a voltage to a carbon-based material in the presence of specific solvents, which promotes the formation of graphene sheets spaced apart by a significant distance, allowing for high functionalization densities and reversible covalent bonding with species, thereby preventing aggregation and enhancing dispersibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional methods are used to obtain graphene, then graphene can be produced, but it aggregates and has low functionalization density
Solution Approach 1:
The method segments the graphene production process into distinct stages: electrochemical exfoliation to create individual sheets, followed by controlled functionalization. This segmentation prevents aggregation by treating graphene sheets individually rather than as bulk material, enabling high functionalization density on each sheet while maintaining dispersion.
Solution Approach 2:
The invention changes key parameters including applying specific voltage ranges (−2.2 V to −3.15 V) during electrochemical exfoliation, controlling solvent composition (mixtures like DMF/acetonitrile or NMP/acetonitrile), and regulating functionalization conditions. These parameter changes enable simultaneous achievement of high functionalization density and prevention of aggregation.
2Quantity of substance
If voltage is applied to functionalize graphene, then functionalization density increases, but aggregation may occur
Solution Approach 1:
The invention uses specific solvent mixtures (e.g., DMF/acetonitrile, NMP/acetonitrile) as intermediaries during the electrochemical functionalization process. These solvent systems mediate between the applied voltage and the graphene sheets, enabling controlled functionalization while maintaining dispersibility and preventing aggregation through their specific surface tension and electrochemical properties.
Solution Approach 2:
The method employs periodic voltage application with controlled ramp rates (2-40 μV/s) during electrochemical functionalization. This periodic, controlled voltage application allows functional groups to be introduced gradually at high density while preventing sudden structural changes that would cause aggregation, thereby maintaining reliability of dispersibility.
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 functionalization densities of graphene, preventing aggregation and enabling efficient dispersibility and functionalization, suitable for applications requiring self-healing and superlubricant properties.
Implementation Method 1
application of a voltage to a carbon-based material in the presence of specific solvents, which promotes the formation of graphene sheets spaced apart by a significant distance
Implementation Method 2
The functional group is capable of forming a reversible covalent bond with a species
Implementation Method 3
The combination of solvents comprises a solvent with a surface tension within 25% of a surface tension of the carbon-based material
Data Source
AI summary
Carbon-based materials, and associated methods and articles, are generally provided. In some embodiments, a carbon-based material comprises a carbon-based portion and a functional group bonded to the carbon-based portion. The functional group may be capable of forming a reversible covalent bond with a species. Carbon may make up greater than or equal to 30 wt % of the carbon-based portion. The carbon-based portion may comprise graphene, and a ratio of a total number of functional groups in a plurality of functional groups bonded to the graphene to a total number of carbon atoms in the plurality of carbon atoms of the graphene may be greater than or equal to 1:50. The carbon-based portion may comprise graphene, and greater than or equal to 70% of the graphene sheets may be spaced apart from their nearest neighbors by a distance of greater than or equal to 10 Å. A method may comprise applying a voltage to a carbon-based material. The voltage may be applied in the presence of a combination of solvents comprising a dissolved species. The combination of solvents may comprise a solvent stable at voltages of greater than or equal to −3.15 V and less than or equal to −2.2 V and/or may comprise a solvent with a surface tension within 25% of a surface tension of the carbon-based material. The voltage may be a decreasing voltage that decreases at a rate of greater than or equal to 2 μV/s and less than or equal to 40 μV/s and has a value of greater than or equal to −2.2 V and less than or equal to −3.15 V at at least one point in time.