News — Graphene oxide

Graphene oxide is part of the graphene family – two dimensional materials based on a honeycomb framework of carbon atoms. While graphene is pure carbon, graphene oxide has a series of oxygen functionalities decorating the surface of the honeycomb carbon structure. The oxygen functional groups can be complex, often containing alcohol, acid and epoxy units.

The presence of oxygen groups leads to significantly different properties when comparing graphene and graphene oxide. For example, graphene oxide can disperse easily in water, while graphene will not disperse. This is because the oxygen groups make graphene oxide a hydrophilic material, allowing water molecules to intercalate between the layers, separating them and forming a stable dispersion. As graphene is a hydrophobic material, this does not occur when trying to disperse graphene in water.

Another interesting difference between graphene and graphene oxide are their conductive properties, in terms of both thermal and electrical conductivity. While graphene has exceptionally high conductivity, graphene oxide is considered an insulator. Both materials have the same carbon framework, and as such the difference in functionality is directly related to the presence of the oxygen groups. The lower the oxygen content in graphene oxide, the higher the conductivity of the material.

There are some instances where the dispersion characteristics of graphene oxide are needed, but the properties of graphene are more relevant. In these instances, it is sometimes possible to convert graphene oxide into a material more similar to graphene in situ. This is done by reducing the graphene oxide, either chemically or thermally, to leave reduced graphene oxide. Reduced graphene oxide has a significantly lower oxygen content than graphene oxide, resulting in properties much closer to those of graphene. Reduced graphene oxide is distinguished from graphene because it will not have a pristine surface – the removal of oxygen groups usually leaves some defects on the surface, including some remaining oxygen functionality. For many applications, the surface of reduced graphene oxide is appropriate for yielding the desired functionality, in other instances the defects can lead to new, different properties for the material which make it interesting in its own right.

For more information on graphene oxide and how it could be of use for your research, please get in touch and a member of our team will be happy to discuss your work.

The GOgraphene team have added a new Graphene Oxide Analysis page to the webshop

There are currently no industry standards for analysing graphene related materials, however as the volume of research surrounding this exciting family of two dimensional materials grows, best practises for analysis are emerging. In order to provide the most relevant information to GOgraphene customers, William Blythe has worked extensively to gather high quality analysis using the techniques most appropriate to characterise the graphene oxide materials manufactured at their site in the UK.

Previously, William Blythe has communicated new graphene oxide analysis via the blog and in the specification of the products available online. To make this information easier to access, a new Graphene Oxide Analysis page has been added to the GOgraphene site. Information currently available on the page includes XPS (X-ray photoelectron spectroscopy), TGA (thermogravimetric analysis), AFM (atomic force microscopy), and SEM (scanning electron microscopy) on typical batches of their graphene oxide products. Wherever possible, the results are backed up with visual representations of the analysis, generally in the form of the raw data obtained by William Blythe on their products. The intention of this page is to provide GOgraphene customers with direct access to the most up-to date information on the products they are purchasing. As new analysis is obtained by William Blythe on their products, new entries will be added to the page and any existing information will be updated if new data becomes available. Any new additions to the Graphene Oxide Analysis page will be communicated via the GOgraphene blog, with all entries on the Graphene Oxide Analysis page entered in alphabetical order to make navigation to the data easier.

William Blythe intends to support the development of commercial applications for graphene oxide materials by working with customers. If you have any questions about the analytical results displayed on this site, or would like the GOgraphene team to consider carrying out other characterisation techniques on their products, please get in touch and a member of the team will be happy to discuss your needs further.

Last year was a busy year for the GOgraphene team, with the launch of the graphene oxide webshop in August 2016. Over the past few months GOgraphene have worked hard to improve the site based on customer feedback. This has led to the addition of an FAQ page to help customers understand more about graphene oxide as a material as well as the products available through their webshop. GOgraphene have also added a new Delivery Charges page to allow customers the opportunity to estimate their delivery charges before they proceed to checkout. Delivery charges are based on the shipping destination, with free shipping on all orders over $500.

As well as adding new pages, the GOgraphene team have also added graphene oxide flake to their product listings. As a product, the GOgraphene team believe this sits well between the graphene oxide powder and aqueous dispersions previously available on the site. This is because graphene oxide flake allows customers to use their graphene oxide in non-aqueous systems but at a lower cost than the freeze dried powder. The difference in cost is a direct consequence of the alternative drying technique used. It should be noted that graphene oxide flake will not be suitable for all researchers as it will need high energy sonication to achieve a dispersion while the freeze dried powder will disperse with mild sonication.

The GOgraphene team would like to take this as an opportunity to thank all of their customers for their support in 2016. It has been an exciting year and since the launch last summer support for GOgraphene has continued to grow. We would like to wish everyone a happy new year and look forward to all of the graphene oxide research to come in 2017.

William Blythe Ltd, the manufacturer of all of the graphene oxide materials supplied via the GOgraphene webshop has a clear objective to produce industrially relevant quantities and quality of graphene oxide in order to support the development and commercialisation of graphene oxide applications. As a result, the company has started work on scaling up the manufacture of graphene oxide, an exciting two-dimensional material from the graphene family.

Supply of research scale quantities of graphene oxide through the GOgraphene webshop became possible when William Blythe reached the large lab scale of manufacture. Batches of graphene oxide are currently prepared on the 30 L scale by a Development Chemist, ensuring each batch meets the same high quality expectations of all William Blythe Ltd products. As demand for William Blythe’s graphene oxide is increasing, the company is now looking at scaling their production to 3,000 L batches, allowing an output of up to 25 kg of dried equivalent graphene oxide per batch. Once William Blythe is able to manufacture on this scale, the company will be well placed to provide larger quantities of their graphene oxide products to customers looking to scale up their graphene oxide applications. As such, both initial research quantities (gram and millilitre scale) and initial scale-up quantities (kilogram and litre scale) will be available for purchase from William Blythe Ltd across all sectors and industries who have an interest in using graphene oxide to enhance their products.

The scale up of manufacture is a key step towards William Blythe’s stated objective of providing high quality, commercially relevant quantities of graphene oxide to promote the development of commercial applications for graphene oxide. If you have any questions regarding William Blythe's proposed roadmap for graphene oxide scale up please get in touch. Any enquiries received regarding higher volumes of graphene oxide will be passed to your local Business Manager, who will get in touch to discuss your needs further.

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.