Thermal Plasma Synthesis of Graphene Quantum Dots

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Solution Overview

Problem

Current methods for producing graphene quantum dots face limitations in large-scale production, size control, and crystallinity, which hinders their application in various fields due to low-cost production and mass production challenges.

Innovation Solution

A method involving thermal plasma is used to produce graphene quantum dots by injecting a carbon source into a thermal plasma jet, allowing carbon atoms to collide within a tube, enabling control over the size and crystallinity of the dots through adjustments in tube length and carbon source supply, and separating different types using polar and nonpolar solvents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional methods (top-down or bottom-up) are used to produce graphene quantum dots, then graphene quantum dots can be obtained, but large-scale production and mass production are limited

Engineering Contradiction:

Improvelarge-scale production capabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent replaces conventional mechanical or chemical methods with thermal plasma technology. The thermal plasma provides high-energy environment for direct carbonization of hydrocarbon gases, enabling continuous large-scale production of graphene quantum dots without complex mechanical processing or multi-step chemical reactions

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes parameter changes in the thermal plasma process, specifically controlling plasma power, gas flow rates, and reactor temperature to optimize graphene quantum dot production. By adjusting these parameters, the process achieves both high productivity and controlled quantum dot characteristics

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If conventional production methods are used, then graphene quantum dots are produced, but size control precision is insufficient

Engineering Contradiction:

Improvequantum dot size controlVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent implements feedback control by monitoring the size distribution of produced graphene quantum dots and adjusting plasma process parameters accordingly. This closed-loop control enables precise size control while maintaining relatively simple process equipment

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent employs dynamic control of plasma parameters during the production process. By dynamically adjusting power input and gas flow rates based on real-time production conditions, the process achieves precise size control without requiring overly complex static equipment configurations

Inventive Principle:

Principle #15Dynamics

3Reliability

If conventional methods are used to produce graphene quantum dots, then production can proceed, but crystallinity and photoluminescence properties are insufficient

Engineering Contradiction:

Improvecrystallinity and photoluminescence qualityVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent utilizes phase transitions in the thermal plasma process, where hydrocarbon gases transition through plasma phase to form carbonized graphene quantum dots. The high-energy plasma environment promotes proper crystallization during this phase transition, achieving high crystallinity and photoluminescence quality

Inventive Principle:

Principle #36Phase transitions

Solution Approach 2:

The patent performs preliminary carbonization of hydrocarbon gases in the thermal plasma before the carbon atoms aggregate into graphene quantum dots. This preliminary high-energy treatment ensures proper crystalline structure formation early in the process, reducing the need for additional energy-intensive post-processing steps

Inventive Principle:

Principle #10Preliminary action

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 approach allows for continuous large-scale production of high-crystallinity graphene quantum dots with controlled sizes from a few nanometers to hundreds of nanometers, enhancing their photoluminescence and applicability in diverse applications.

Implementation Method 1

injecting a carbon source into a thermal plasma jet to pyrolyze the carbon source so as to form a carbon atomic beam

Methodology Applied

Scientific EffectPyrolysis: Pyrolysis

Implementation Method 2

thermal plasma jet to pyrolyze the carbon source

Methodology Applied

Scientific EffectThermal heating: Heating

Data Source

PatentUS10435301B2Graphene quantum dots with different types and method for obtaining each of different types of graphene quantum dots

Publication Date: 2019.10.08 SEOUL NATIONAL UNIVERSITY R&DB FOUNDATION

AI summary

The present application provides a method for producing a graphene quantum dot using thermal plasma, comprising injecting a carbon source into a thermal plasma jet to pyrolyze the carbon source so as to form a carbon atomic beam and allowing the carbon atomic beam to flow in a tube connected to an anode to produce a graphene quantum dot. The present application also provides an isolated graphene quantum dot from different types of graphene quantum dots and method for obtaining each of an isolated graphene quantum dot from different types of graphene quantum dots.