News — graphene oxide flake

William Blythe currently offer two different solid forms of graphene oxide through the GOgraphene webshop; a powder and a flake.

Both products are formed from the aqueous dispersions of graphene oxide manufactured at William Blythe Ltd, and both products meet the same rigorous quality standards as all William Blythe products. We are often asked if there is any difference between these two products, and if so what those differences are. The simple answer to these questions is that while they are different, the differences allow the user to pick the product most suitable for their work rather than one being better than the other.

The flake and the powder are different products because of the drying technique used to produce them, which in turn leads to differences in the properties of the materials. GOgraphene’s graphene oxide powder is best described as a fine brown dust, which will disperse easily with minimal energy input. GOgraphene’s graphene oxide flake is visually different – the flakes are dark brown-amber discs with a diameter of 0.3-0.7 cm. Our graphene oxide flake has been specifically developed to allow researchers who cannot handle dusty solids to work with graphene oxide in non-aqueous systems.

The difference in physical form of these two materials affects the dispersibility of the products. The powder has a higher surface area by definition, this means it is easier to disperse. The flake can be considered as compacted graphene oxide layers; which water molecules need to intercalate between in order to form a dispersion. According to the work carried out by the GOgraphene team, there is no difference in the dispersion stability based on the solid form used. The difference lies in the ease of dispersion; where our graphene oxide powder can be dispersed with a very mild energy input, the flake requires higher energy sonication. For labs which are not equipped with this facility, the powder is undoubtedly the more appropriate option.

To summarise, our graphene oxide flake and freeze dried powder are different products, neither of which are better than the other in all applications. They are complementary products which find purpose in different research programmes. If you would like to speak to a team member regarding which product is more suitable for your work, we would be more than happy to discuss your research.

The GOgraphene Team have been investigating how to reduce graphene oxide to rGO

The GOgraphene team believe that understanding graphene oxide is the key to finding suitable applications. For many applications, the properties of reduced graphene oxide rather than graphene oxide are required by the user. It is well known that graphene oxide can be reduced through either chemical or thermal treatments, however the GOgraphene team wanted to obtain their own data. Considering the thermal reduction of graphene oxide, the GOgraphene team decided to investigate how to reduce their graphene oxide.

A small sample of graphene oxide flake was placed in a convection oven at 200 °C and left for 15 minutes. The material removed from the oven was visually different from the graphene oxide flake used. The relatively even size distribution of brown/amber coloured graphene oxide discs had become black, with variable shapes and sizes observed.

XPS analysis was conducted to determine how much the oxygen content within the material had dropped by. The graphene oxide flake used had an oxygen content of 21.2% before thermal treatment and 12.9% after treatment. This coincides well with the TGA (thermogravimetric analysis) carried out on GOgraphene’s graphene oxide flake which shows multiple decomposition steps when analysed between ambient and 1000 °C. Based on the TGA data, to achieve full reduction the GOgraphene team would predict that the sample would need to be heated to 350 – 550 °C.

In the future, the GOgraphene team intends to continue the investigation of thermal reduction of graphene oxide to rGO (reduced graphene oxide), with the intention of understanding how low the oxygen content can be driven. The team will also expand their work to examine chemical reductions, which in some applications may be more suitable than thermal reduction. In the meantime, the GOgraphene team hope that those interested in learning more about how to reduce graphene oxide find this latest news both interesting and useful. If you have any questions, please get in touch.

The GOgraphene team are pleased to announce the addition of graphene oxide flake to their high quality graphene oxide product range. 

The graphene oxide flake offered is formed by drying thin layers of an aqueous dispersion and results in brown-amber discs with approximate diameters of around 0.3 cm – 0.7 cm. As the graphene oxide flakes are made directly from GOgraphene's 1% aqueous graphene oxide dispersions, the flake meets the same stringent quality requirements of the other GOgraphene products.

By drying the GOgraphene graphene oxide dispersions at ambient temperature it is possible for GOgraphene to offer flake as an alternative solid to the freeze-dried powder. The resulting solid products are different and a customer’s choice to use powder or flake will depend on their research facilities. Graphene oxide flake will require more energy to disperse when compared to the freeze dried powder. To check the dispersibility of their graphene oxide flake, the GOgraphene team added their graphene oxide flake to deionised water at a concentration of 0.5 mg/mL and left it to sonicate in an ultrasonic bath. After one hour of sonication in an ultrasonic bath all of the flake had dispersed. The dispersion was left to stand for 7 days, at the end of which no solids were observed. No work has been carried out by GOgraphene on dispersing their graphene oxide flake in any other medium yet. This will be investigated in future work, with findings communicated via the GOgraphene blog. 

GOgraphene’s graphene oxide flake is now available to purchase online in 1 g and 5 g pack sizes and is available for shipment within 21 days of purchase. If you have any questions please get in touch via our enquiry form.