Large scale oxidized graphene production for industrial applications
View Patent ↗Existing methods of producing high quality graphene/graphite oxides are generally accomplished by exfoliating graphite into flakes and oxidizing the graphite flakes with strong oxidizers under extreme conditions and require careful purification. The oxidizers are typically strong acids used in high concentrations at elevated temperatures requiring complicated purification processes to yield oxidized graphene/sheets. The existing processes can cost up to $12,000/gram. This invention uses a mild oxidant combined with mechanical processing where the sole products are oxidized graphite/graphene and water without the need for further purification.
1. A method of making oxidized graphene, consisting essentially of:
placing graphite into water containing an oxidizing agent, wherein the oxidizing agent is at least one of CO 2 , O 2 , steam, N 2 O, NO, NO 2 , O 3 , ClO 2 , or H 2 O 2 , at a concentration wherein the oxidation potential is less than 2V and wherein said oxidizing agent has an oxidation potential less than 2V;
mechanically exfoliating in a mechanical milling apparatus the graphite into oxidized graphene flakes in the water containing the oxidizing agent, wherein the mechanical exfoliation is in an Attrition mill, a dry grind Attritor, a wet grind Attritor, a regular speed Attritor, a high speed Attritor, an Attritor, or a stirred media mill; and
separating the oxidized graphene flakes from the water.
2. The method of claim 1 , wherein the step of mechanically exfoliating graphite into oxidized graphene flakes in done in a stirred media mill.
3. The method of claim 1 , wherein the pH of the water containing the oxidized graphene flakes is from pH 2 to pH 9.
4. The method of claim 1 , wherein the pH of the resulting water of the oxidized graphene flakes mixture is about 7.
5. The method of claim 1 , wherein the oxidized graphene flakes are oxidized from 1% to 15%.
6. The method of claim 1 , further comprising the step of precipitating any remaining graphite by increasing the pH of the mixture above pH 9, or below a pH of 3.
7. The method of claim 1 , wherein the oxidizing agent is an aqueous oxidizing agent.
8. The method of claim 1 , wherein the method produces an output that is limited to flat oxidized graphene flakes and water.