Graphene Preparation via Mixed Acid Oxidation
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Solution Overview
Problem
Current methods for synthesizing graphene face challenges such as low yield, unstable product quality, high costs, and difficulties in achieving large-scale production due to the use of strong acids and oxidants, which lead to equipment corrosion and low reaction rates in the preparation of graphene oxide.
Innovation Solution
A method involving a mixed acid system is employed, where graphite is treated with a combination of organic and inorganic strong acids and oxidants, followed by ultrasonication and controlled hydrolysis to produce graphene oxide, which is then reduced using an acidic reducing agent to obtain high-quality graphene with improved dispersibility and reaction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional oxidation-reduction process is used to prepare graphene oxide, then graphene can be produced with stable quality, but equipment corrosion is severe due to strong acids and oxidants
Solution Approach 1:
The patent changes the chemical parameters of the oxidation process by using a mixed acid system (sulfuric acid, nitric acid, and phosphoric acid) with specific concentration ratios, replacing traditional strong oxidants like potassium permanganate. This parameter modification reduces the corrosiveness while maintaining oxidation effectiveness, thus protecting equipment while producing stable quality graphene oxide
Solution Approach 2:
The patent employs a composite acid system combining three different acids (sulfuric acid, nitric acid, and phosphoric acid) in specific proportions. This composite approach leverages the complementary properties of each acid: sulfuric acid for intercalation, nitric acid for oxidation, and phosphoric acid for buffering and corrosion reduction, achieving both stable product quality and reduced equipment corrosion
2Reliability
If solid oxidants are used in the oxidation process, then the reaction can proceed, but the reaction rate is low due to solid-solid reaction between oxidant and graphite
Solution Approach 1:
The patent changes the physical state parameter of the oxidant from solid to liquid by using liquid acids (sulfuric acid, nitric acid, phosphoric acid) instead of solid oxidants like potassium permanganate. This state change enables liquid-solid reaction between the acid mixture and graphite powder, dramatically increasing the reaction rate and enabling efficient mass production while maintaining reaction feasibility
Solution Approach 2:
The patent introduces phosphoric acid as an intermediary substance in the mixed acid system. Phosphoric acid acts as a buffer and mediator that facilitates the interaction between sulfuric acid and nitric acid with graphite, improving the overall reaction efficiency and rate while reducing the need for excessive strong oxidants
3Manufacturing precision
If physical methods like mechanical exfoliation are used to synthesize graphene, then the graphene layers are intact, but the yield is low and production cost is high
Solution Approach 1:
The patent replaces the mechanical exfoliation system with a chemical oxidation-reduction system. Instead of using mechanical force to peel graphite layers, the patent uses chemical reactions (oxidation of graphite to graphene oxide followed by reduction to graphene) to produce graphene. This substitution enables high-yield mass production while maintaining adequate layer integrity through controlled chemical processes
Solution Approach 2:
The patent modifies the chemical parameters of the oxidation process using a mixed acid system with controlled concentrations and ratios of sulfuric acid, nitric acid, and phosphoric acid. By optimizing these parameters, the process achieves high yield of graphene oxide with controlled oxidation levels, which after reduction produces graphene with good layer integrity and high production efficiency
4Reliability
If strong oxidants are used to prepare graphene oxide, then oxidation can be achieved, but heat release is large causing violent reaction and potential explosion
Solution Approach 1:
The patent changes the thermal parameters of the oxidation process by using a mixed acid system that operates at lower temperatures compared to traditional strong oxidants. The phosphoric acid component acts as a thermal buffer, reducing the exothermic nature of the reaction. This allows effective oxidation to proceed with controlled heat release, preventing violent reactions and potential explosions
Solution Approach 2:
The patent uses a composite acid system where phosphoric acid serves as a thermal buffer and heat sink among the three acids. This composite approach distributes and moderates the heat release across multiple acid components, preventing localized overheating and violent reactions while maintaining effective oxidation of graphite to graphene oxide
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 results in graphene with large layers, high specific surface area, and superior properties, enabling large-scale industrial production while minimizing equipment corrosion and optimizing reaction efficiency.
Implementation Method 1
a predetermined amount of oxidant is added to a second acid component... to obtain a second acid system... The second acid system is added dropwise to the first acid system... to obtain a mixed solution... After treatment, the mixed solution is added dropwise to water... to obtain a graphite oxide suspension
Implementation Method 2
The graphite powder obtained in Step a is added to an intercalator that is a first acid component, and ultrasonicated to obtain a graphite-first acid component dispersion... The mixed solution is ultrasonically stirred for 0.5-3 h... ultrasonically exfoliated at 100-600 W for 0.5-3 h
Implementation Method 3
A reducing agent is added to the graphene oxide dispersion obtained in Step a... The graphene oxide dispersion treated with the reducing agent in Step b is heated for 5-30 min in microwave... to obtain graphene
Implementation Method 4
The graphene oxide dispersion treated with the reducing agent in Step b is heated for 5-30 min in microwave at 400-900 W
Implementation Method 5
the mixed solution is added dropwise to water in an environment of 70-100°C for the purpose of hydrolyzing the substance in the mixed solution
Data Source
AI summary
The present invention relates to a preparation method of graphene oxide based on mixed acid system. The method consists of the following steps. a. Preparation of graphite powder; b. Preparation of suspension liquid of first acid system; c. Preparation of second acid system; d. Preparation of graphene oxide. The invention also relates to a preparation method of graphene using graphene oxide obtained by method mentioned above. The method consists of the following steps. e. Preparation of graphene oxide-dispersant solution; f. Reduction of graphene oxide; g. Process of supersonic stripping; h. Obtaining graphene by separation and drying. The preparation methods of graphene oxide and graphene in our invention could reduce the dosage of strong acid as well as heat release of chemical reaction, and cause less corrosion to our equipments, which makes the reaction more effective and properties of graphene products better, facilitating the achievement of large scale industrial production.