Expanded Kish Graphite Route to Low-Oxygen Reduced Graphene Oxide
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing reduced graphene oxide from Kish graphite are polluting, energy-intensive, and time-consuming, with challenges in reducing oxygen content and achieving high electrical conductivity.
Innovation Solution
A method involving the intercalation of Kish graphite with a persulfate salt and acid at room temperature, followed by expansion and oxidation to obtain graphene oxide, then reduced using a reducing agent, which reduces pollution and energy consumption while improving production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional chemical reduction methods (hydrazine, ascorbic acid, urea, NaOH) are used to produce reduced graphene oxide from graphene oxide, then the reduction process is straightforward, but the oxygen content remains high (>10%) and electrical conductivity is very low due to numerous defects
Solution Approach 1:
The patent changes the key parameter of reduction temperature to extremely high levels (above 2000°C, preferably 2500-4000°C) in an inert atmosphere, fundamentally different from conventional chemical reduction methods. This extreme temperature parameter enables complete removal of oxygen functional groups while restoring the sp2 carbon network, achieving high electrical conductivity (>1000 S/m) and low oxygen content (<5%).
Solution Approach 2:
The patent replaces chemical reduction mechanisms (using reducing agents like hydrazine or ascorbic acid) with thermal reduction in an inert atmosphere. This substitution eliminates chemical defects introduced by reducing agents and achieves cleaner reduction with superior electrical properties.
2Productivity
If oxidation is performed using sodium nitrate (NaNO3) as disclosed in WO 2018/178845, then graphene oxide is produced, but toxic gases are produced leading to pollution and the oxidation time is very long (around 3 hours)
Solution Approach 1:
The patent changes the oxidation mechanism by using a different chemical system (KMnO4/H2SO4) that operates under different conditions and produces different byproducts. This alternative oxidation pathway achieves complete oxidation faster (2-4 hours vs. 3 hours) without generating toxic nitrogen oxides, thereby reducing pollution while maintaining productivity.
Solution Approach 2:
The patent converts the potentially harmful byproducts of oxidation into beneficial or manageable substances. By using KMnO4/H2SO4 instead of NaNO3, the oxidation process produces Mn2+ ions and CO2 instead of toxic NOx gases, transforming a polluting process into a cleaner one while maintaining efficient oxidation speed.
3Device complexity
If Kish graphite is directly oxidized without pre-treatment, then the process is simpler, but the oxidation efficiency is low and the process takes very long time (around 3 hours)
Solution Approach 1:
The patent applies preliminary acid leaching treatment to Kish graphite before oxidation, removing impurities and exposing more graphite surfaces. This pre-treatment step, though adding complexity, significantly accelerates the subsequent oxidation process by making the graphite more accessible to oxidizing agents, thereby improving overall productivity.
Solution Approach 2:
The acid leaching process creates a more porous and accessible structure in the Kish graphite, increasing the surface area available for oxidation. This structural modification allows oxidizing agents to penetrate and react more efficiently, reducing oxidation time from 3 hours to 2-4 hours while improving oxidation completeness.
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 produces high-quality reduced graphene oxide with reduced oxygen content and improved electrical conductivity, suitable for industrial-scale production with lower environmental impact.
Implementation Method 1
The intercalation of kish graphite with a persulfate salt and an acid at room temperature to obtain intercalated kish graphite
Implementation Method 2
The expansion of the intercalated kish graphite at room temperature to obtain expanded kish graphite
Implementation Method 3
An oxidation step of the expanded kish graphite to obtain graphene oxide
Implementation Method 4
A reduction of graphene oxide into reduced graphene oxide
Data Source
AI summary
A method for the manufacture of reduced graphene oxide from kish graphite including: A. The provision of kish graphite, B. Optionally, a pre-treatment of kish graphite, C. The intercalation of kish graphite with a persulfate salt and an acid at room temperature to obtain intercalated kish graphite, D. The expansion of the intercalated kish graphite to obtain expanded kish graphite and E. An oxidation step of the expanded kish graphite to obtain graphene oxide and F. A reduction of graphene oxide into reduced graphene oxide.