Green preparation method of graphene oxide proposed by Institute of Metals, Chinese Academy of Sciences

Graphene oxide is an important graphene derivative. It was originally used as a precursor for the preparation of graphene in macroscopic quantities. In recent years, it has become more and more popular because of its unique physical and chemical properties and broad application prospects. Pay attention to it. Due to the large amount of oxygen-containing functional groups, graphene oxide has good dispersibility in water and is easy to assemble and functionalize. Therefore, it is widely used in the preparation of multifunctional separation membranes, high-conductivity and high-strength fibers, ultra-light superelastic aerogels, etc. It is a kind of functional material and has a good application prospect in electrochemical energy storage, catalysis, biomedicine, composite materials and so on.

Currently, graphene oxide is mainly prepared by exfoliating graphite oxide. The preparation of graphite oxide has been more than 150 years old. Both the original Brodie method (1859) and the later developed Staudenmaier and Hummers methods are based on graphite with a large amount of concentrated nitric acid, concentrated sulfuric acid and potassium permanganate. The reaction of a complex strong oxidant is realized, not only the risk of explosion, but also serious pollution and long reaction period. Taking the most commonly used Hummers method as an example, the oxidant consists of concentrated sulfuric acid and potassium permanganate, and its typical material to mass ratio ( mass ratio) is 40:3:1 (concentrated sulfuric acid: potassium permanganate: graphite). The reaction ultimately produces more than 1000 mass units of acidic wastewater. Moreover, the highly active Mn2O7 intermediate may explode at high temperatures, and the completion of the oxidation reaction may take hours to hundreds of hours.

Recently, the Advanced Carbon Materials Research Department of the National Research Center for Materials Science of the Institute of Metal Research, Chinese Academy of Sciences proposed a new method for the oxidation of electrolyzed water, breaking the traditional idea of ​​oxidizing graphite by strong oxidants for more than 150 years, and realizing graphene oxide. Safe, green, and ultra-fast preparation. The method first intercalates graphite in concentrated sulfuric acid and then oxidizes the intercalated graphite in dilute sulfuric acid. Oxygen isotope tracing and free radical trapping experiments show that the oxygen element in graphene oxide is mainly derived from water in the electrolyte, and a large amount of highly reactive oxygen radicals generated by electrolyzed water react with graphite to form graphene oxide. There is almost no loss of sulfuric acid in the reaction, and no other substances are formed, which can be repeatedly used for electrochemical reactions. The study also found that the oxidation rate of electroplated water to produce graphene oxide is more than 100 times faster than the existing method, and the obtained material is similar to the existing method, and is easy to be continuously prepared. The method effectively solves the problem of long-term explosion explosion, environmental pollution and long reaction period of the preparation of graphene oxide, and is expected to greatly reduce the preparation cost and promote the industrial application of graphene oxide.

Relevant research results were published in Nature-Communication, and related technologies have applied for Chinese invention patents and PCT patents. The research was funded by the Ministry of Science and Technology's key research and development program, the National Natural Science Foundation of China Outstanding Youth Fund, major projects, and innovative group projects.