Q: What is graphene oxide? A: Graphene oxide (GO) is a two-dimensional material in which oxygen-containing functional groups are introduced into the graphene skeleton. The introduction of oxygen-containing functional groups, on the one hand, destroys the ideal π-electron conjugated structure of graphene, changing it from a conductor to an insulator. On the other hand, these functional groups also confer functions such as hydrophilicity, so that graphene oxide can form stable colloids in water and some low molecular weight alcohols. Using these chemically active functional groups, covalent bonding of graphene oxide with other materials can also be realized.
Q: What are the categories of graphene materials? A: According to the different preparation processes, graphene materials can be divided into two categories: graphene oxide and graphene, and graphene can be divided into graphene nanosheets prepared by physical method, usually denoted by GNP, and reduced graphene oxide prepared by redox method, usually denoted by rGO, according to the different preparation processes
Q: What are the differences in the usage conditions of these three types of graphene products? A: GO has better hydrophilicity and can be stably dispersed in water without adding any additives, but some lattice defects are introduced in the process of oxidative intercalation, so GO is almost non-conductive; GNP has a complete lattice and better electrical conductivity, but GNP has a strong hydrophobicity, which makes it difficult to be dispersed without dispersing additives and the number of layers is higher than that of graphene oxide; rGO has a higher conductivity and dispersibility between GO and GNP; rGO also needs to add appropriate amount of dispersing additives in the process. The conductivity and dispersibility of rGO is between GO and GNP, and it is necessary to add appropriate amount of dispersing additives in the process.
Q: Can graphene oxide dispersion be used directly? A: It can be used directly after opening, if it has been placed for a long time, it can be used after ultrasonic dispersion for 5~10min, the ultrasonic time should not be too long, after the ultrasonic time is too long, the temperature of the water bath rises, and graphene oxide is easy to deoxidize, resulting in poor dispersion effect.
Q: Graphene oxide can be dispersed into which agents? A: Graphene oxide can be stably dispersed in water due to a large number of oxygen-containing functional groups, in addition, ethanol, acetic acid, NMP, DMF and so on are also good dispersants of graphene oxide.
Q: How to store the unused graphene oxide dispersion after opening? A: It is recommended to be stored in a ventilated and dry environment at a temperature not higher than 35ºC, do not contact with metals, vitamin C, NaHSO3, NaBH4 and other reducing reagents when storing, and keep it sealed at low temperature after opening.
Q: What is the particle size of graphene oxide? A: At present, the particle size of our graphene oxide products is less than 5μm, if you need other sizes, please contact us for customization.
Q: Is the smaller the particle size of graphene oxide, the better the dispersibility? A: The dispersibility of graphene oxide has a little relationship with the particle size, but there is no direct influence on the relationship, the more critical influencing factor is the degree of oxidation as well as the dispersing technology, the oxygen content of more than 20% of the GO has been able to meet the normal dispersion needs.
Q: Graphene oxide dispersed in water is acidic or alkaline? A: Graphene oxide is weakly acidic when dispersed in water due to its acidic oxygen-containing functional groups. Some GO dispersions on the market that are more acidic are due to incomplete cleaning and high content of impurity ions.
Q: Can graphene oxide be stabilized under alkaline condition? A: Weakly alkaline conditions can be stable, but pH more than 11 is prone to agglomeration, because the adsorption of graphene oxide and metal ions under strong alkaline conditions changes the zeta potential of the lamellae, resulting in mutual attraction between the lamellae. In addition, it is easy to deoxidize under heating condition in alkaline solution, resulting in poor dispersion of the product.
Q: Why is the color of graphene oxide dispersion different from graphene dispersion? A: According to the different concentration, graphene oxide dispersion shows brownish yellow to blackish brown from low to high concentration respectively. The reason for the color of graphene oxide is the destruction of its conjugated structure during the preparation process, the opening of the optical band gap, the hanging unsaturated bonds and the joint action of oxygen-containing functional groups. Graphene with a perfect conjugated structure does not have an optical band gap, and by destroying the conjugated structure or narrowing the conjugated structure, graphene can absorb or emit a certain range of wavelengths of light. Graphene oxide has suspended unsaturated double bonds and other color-generating groups, together with the oxygen-containing functional groups of the color-assisting groups, the corresponding color is produced.
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