What is the Difference Between Graphene Oxide and Reduced-Graphene Oxide

Graphene oxide and reduced-graphene oxide are two forms of graphene. Graphene is a single layer of carbon atoms with a hexagonal lattice arrangement. Graphite is made from graphene. 

What is the difference between graphene oxide and reduced-graphene oxide? In graphite oxide, the oxygen content is high, whereas in reduced graphene oxide, the oxygen content is low.

Key Areas Covered

1. What is Graphene Oxide  
      – Definition, Features, Composition 
2. What is Reduced-Graphene Oxide
      – Definition, Features, Composition 
3. Similarities Between Graphene Oxide and Reduced-Graphene Oxide
      – Outline of Common Features
4. Difference Between Graphene Oxide and Reduced-Graphene Oxide
      – Comparison of Key Differences
5. FAQ: Graphene Oxide and Reduced-Graphene Oxide
      – Answers to Frequently Asked Questions

Key Terms

Graphene Oxide, Reduced-Graphene Oxide, Graphite

What is Graphene Oxide

Graphene oxide is derived from graphene. It’s formed by treating graphite, a naturally occurring form of carbon, with strong oxidizing agents. In this process, functional groups that contain oxygen, such as hydroxyl, epoxy, and carbonyl groups, are added to the graphene surface. The addition of those groups disrupts the crystalline structure, and creates a structure containing spores and hydrophilic material.

Due to the presence of these polar functional groups, graphene oxide is more soluble in water and in other polar solvents. These polar functional groups also cause the reduction of electrical conductivity in graphene. These oxygen-containing groups trap electrons. 

The surface of graphene oxide is highly porous. The large surface area helps with better absorption, filtration, and sensing. Graphene oxides are incorporated into polymers, ceramics, and metals to increase their properties. It is also useful in energy storage devices, water purification, and as a component of electronic devices.

What is Reduced Graphene Oxide

Reduced graphene is a derivative of graphene that has undergone a physical or chemical process to remove a considerable amount of its oxygen-containing groups. Graphene oxide is a precursor to reduced graphene.

The reduction process involves various methods. These include chemical reduction using agents like hydrazine or sodium borohydride, thermal reduction at high temperatures, and electrochemical reduction. Compared to pristine graphene, reduced graphene oxide is generally more affordable and easier to produce in large quantities.

Similarities Between Graphene Oxide and Reduced-Graphene Oxide

1. Graphene oxide and reduced-graphene oxide have a similar hexagonal lattice structure.
2. Furthermore, both materials mainly contain carbon atoms.
3. They exhibit a large surface area
4. In addition, both are excellent thermal conductors.

Difference Between Graphene Oxide and Reduced-Graphene Oxide

Definition

• Graphene oxide is oxidized graphene with oxygen-containing functional groups, while reduced graphene oxide is graphene oxide after chemical or thermal reduction to remove oxygen groups.

Composition

• Graphene oxide contains a high concentration of oxygen-containing functional groups (e.g., hydroxyl, epoxide, carboxyl). Reduced-graphene oxide has significantly lower oxygen content due to the removal of these functional groups during the reduction process.

Hydrophilic Nature

• Graphene oxide is highly hydrophilic due to the polar oxygen-containing groups, whereas reduced-graphene oxide is less hydrophilic.

Surface Area

• Graphene oxide typically has a lower surface area compared to reduced-graphene oxide. 

Conclusion

Graphene oxide (GO) is oxidized graphene with oxygen-containing functional groups. Reduced graphene oxide (rGO) is GO after chemical or thermal reduction to remove oxygen groups. Both of these species have different applications in the industry.

FAQ: Graphene Oxide and Reduced-Graphene Oxide

1. Is reduced graphene oxide the same as graphene?

No, reduced graphene oxide (rGO) is not the same as graphene. rGO is produced by removing oxygen-containing functional groups from graphene oxide, while graphene is a single layer of carbon atoms arranged in a hexagonal lattice.

2. What is the role of reduced graphene oxide?

Reduced graphene oxide (rGO) is a material with applications in energy storage, electronics, and composites. It is usually more affordable and easier to produce in large quantities than graphene oxide.

3. How can you tell the difference between graphene and graphene oxide?

Graphene is a single layer of carbon atoms with a honeycomb lattice arrangement. Graphene oxide is graphene with oxygen-containing functional groups, such as hydroxyl, epoxy, and carboxyl groups.

4. Why reduced graphene oxide is conductive?

Reduced graphene oxide is conductive due to its delocalized π electrons. These electrons can move freely throughout the material, creating a pathway for electrical current.

5. Is reduced graphene oxide soluble?

Reduced graphene oxide is generally not soluble in water. But it can be dispersed in certain solvents like dimethylformamide (DMF) or N-methyl-2-pyrrolidone (NMP) with the help of surfactants or stabilizers.

Reference:

1. “Graphene Oxide.” Science Direct. 
2. “Reduced-Graphene Oxide.” Science Direct. 

Image Courtesy:

1. “GrapheneOxide” By PackBMEengineer (CC BY-SA 4.0) via Commons Wikimedia
2. “Reduced Graphene Oxide” By Wncolombo – Own work (CC BY-SA 4.0) via Commons Wikimedia