News — graphene oxide research

Graphene oxide was first reported in the literature over 150 years ago, at a time when there was little interest in exploring the benefits of the material in the multitude of application areas it is currently being used in. Interest in graphene oxide rose dramatically with the discovery of, and Nobel prize for, graphene. The subsequent years have seen the use of graphene oxide in a diverse range of applications, with many researchers focussing on graphene oxide as a potential precursor material for graphene with specific graphene oxide applications now under development.

With no suppliers, initial graphene oxide researchers were unable to purchase graphene oxide and therefore synthesised all of their own material. Despite multiple graphene oxide suppliers launching a variety of products for this market in the past few years, some researchers are still undecided as to whether they should purchase or make their own graphene oxide for their work. While William Blythe understand that there are always reasons to synthesise your own graphene oxide, we have tried to overcome some of the most common concerns around purchase with our GOgraphene webshop.

Consistent quality 

William Blythe are aware that some suppliers do not offer a consistent product. As an established chemicals manufacturer with over 150 years’ experience supplying chemicals, we ensure our graphene oxide meets the same high standards as our other products before we dispatch your order.

Flexibility

Buying from someone else will always reduce some of the flexibility compared to in house synthesis. William Blythe have tried to overcome this by offering multiple product forms, developing a high concentration dispersion which can be easily diluted and by taking requests for custom functionalisation of our standard material.

Availability 

To keep results comparable, most researchers do not want to swap materials supply part way through their research programme. We monitor our stock levels carefully to make sure we always have enough of our graphene oxide to fulfil our orders. Keep an eye on our lead times if you have any concerns

Volume 

Graphene oxide is currently only available for purchase online in relatively low quantities. Some researchers are concerned that the raw materials availability will prevent their application from being scalable. As William Blythe has already developed scale-up plans, this need not be a concern. Not only is our process is scalable, but within 12 months of demand projections requiring it, William Blythe can scale on to a dedicated multi-tonne production facility.

Price 

Some materials suppliers fluctuate their prices, meaning there are some researchers who do not want to become reliant on a materials supplier. The graphene oxide available on the GOgraphene webshop has never been increased in price. Depending on the currency you are purchasing in, the screen may display slight variations, however our GBP pricing has not been increased since launch.

We hope that the above helps to alleviate some of the concerns which we know exist in the marketplace. If you have other concerns or questions regarding purchase versus in house synthesis, please get in touch. There are a host of benefits to purchasing graphene oxide, including saving time and removing the need for hazardous synthesis. If you are ready to switch to buying graphene oxide, please take a look at our current product portfolio.

Raman spectroscopy has been used to prove William Blythe's graphene oxide readily disperses into monolayers.

Raman spectroscopy is a well-known and very common technique for the analysis of graphene related materials. By assessing the position, intensity and ratios of the D and G peaks, it is possible to learn a lot about the material in question. Useful information from raman spectroscopy include the level of oxidation and whether the graphene oxide is present as single, double or few layer material. The ratio of the D and G peak intensities (ID/IG) can be used to estimate the distance between defects, where the term defects refers to disruption in the bonding structure observed for pristine graphene. When analysing graphene oxide, the number of defects is expected to be high as each oxygen functional group on the surface increases the amount of sp3 hybridisation and therefore reduces sp2 hybridisation.

Recent raman spectroscopy carried out on William Blythe’s graphene oxide proved that the material was fully oxidised with an ID/IG ratio of about 1, which is fairly typical for graphene oxide. An estimation of the number of layers present can be given by comparing the area of the D and G peaks to the area of the silicon substrate peak (ca 950 cm-1). Coupling with an SEM image and applying false colour, it has been possible to illustrate the presence of large quantities of single layer graphene oxide. While some 2 layer and 3+ layer material is present, based on the flake shapes and the nature of spin coating, it is thought that these areas are more likely to be flake overlaps rather than multilayer graphene oxide.

The raman analysis carried out on William Blythe’s graphene oxide shows that the graphene oxide manufactured readily exfoliates into monolayers in aqueous dispersions. This has previously been indicated by the ease of dilution. If you have any questions about this analysis or how you can incorporate graphene oxide into your work, please get in touch.

Have you recently seen a paper related to graphene oxide research that you think the GOgraphene team would be interested in sharing?

The GOgraphene team have started posting entries to the GOgraphene blog about papers they have found particularly interesting, be that for the promising results achieved by the researchers, the application area focussed on or the approach taken to the research.

As a company, William Blythe has a strong history of manufacturing products to tight specifications for multiple applications, with materials tuned for their specific end use. By comparison to the existing William Blythe portfolio, graphene oxide is therefore fairly unique. While the material can be tuned for specific applications through both functionalisation and physical property manipulation, the requirements of graphene oxide in each application are not yet well understood. As a result, graphene oxide is considered applicable to many research areas in its standard form. This results in a huge diversity of application sectors interested in graphene oxide materials.

The GOgraphene team like to stay up to date with graphene oxide research which is being carried out across the globe and have taken to writing brief overviews of some of their favourite pieces. The team are always looking to increase both the breadth and depth of their application knowledge around this material, so if you would like to recommend a paper to the team please let us know – if we really like it we might even include it in a future blog post!

A recent study estimates the annual cost of global corrosion as USD 2.5 trillion. As a result, studying ways in which to reduce corrosion is an extensive research field with many papers published each year on the topic. There are many ways to address the issue of corrosion, from using corrosion-resistant materials to applying coatings. Over the past few years, there have been several publications looking at exploiting the barrier properties of graphene oxide in anti-corrosion coatings.

A focus of graphene based anti-corrosion coatings has been the use of CVD (chemical vapour deposition), however on an industrial scale CVD is accompanied by many potential barriers due to the specialist equipment and arrangements which are needed. A recent paper in Applied Nanoscience used a process which is arguably easier to scale – they took reduced graphene oxide and dip coated it onto mild steel. The work used rGO in 1-propanol and used multiple layers to form a good barrier around the mild steel coupon. The authors found that they could reduce the corrosion of uncoated mild steel from 282 mm/year in water at pH 6.0 to 0.107 mm/year with a 5 layer coating of reduced graphene oxide. With just 3 layers of coating, the corrosion rate was still reduced by 98.7%.

The research also looked at their coated mild steel in hydrochloric acid (0.1 N), sodium chloride solution (3.5 wt%) and sodium hydroxide (1 M). In all three solutions a reduction in corrosion was observed compared to the uncoated mild steel. Using three layers of coating, the researchers were able to reduce the corrosion rate compared to the uncoated mild steel coupon in all three solutions. Corrosion in HCl was reduced by 86.9%, in sodium chloride by 99.5% and in sodium hydroxide by 99.2%.

This research has illustrated another major potential application for graphene oxide; reducing corrosion is a key objective for many, with the benefits felt by people around the world. If you are interested in using graphene oxide in your work, please get in touch.

Appl. Nanosci., 2016, 6, 1175-1181

A recent article published earlier this year investigated the use of graphene oxide in nanocomposites for use as drug carriers.

Graphene oxide has been researched in many application areas, one of which is in drug carriers. The high surface area and potential for functionalisation result in the possibility to load drugs onto the graphene oxide nanosheets. While graphene oxide disperses well in aqueous systems, it has been found that in physiological systems it will aggregate, limiting its potential use. To overcome this issue researchers have looked to both functionalisation of the graphene oxide and the formation of nanocomposites with other materials.

Bacterial cellulose has also recently become of interest as a drug carrier for several reasons, including its good biocompatibility and its web-like structure, which allows it to support drugs. The research presented in a recent paper illustrates the benefit of combining graphene oxide with bacterial cellulose. The study focussed on in vitro studies of the release of ibuprofen, comparing ibuprofen on bacterial cellulose to ibuprofen on a bacterial cellulose/graphene oxide composite. At both a neutral and acidic pH, the GO composite material showed a more sustained and controlled release of ibuprofen than when supported on bacterial cellulose alone. This indicates that the presence of graphene oxide aids in providing a more controlled release of the drug.

The study also noted several other interesting differences between the bacterial cellulose only carrier and the GO composite. Using a cell counting kit 8 assay, the research showed that graphene oxide increased the biocompatibility of the bacterial cellulose. Two different GO loadings were studied in the biocompatibility tests, with the lower loading showing superior performance. This indicates that too much graphene oxide is detrimental in terms of biocompatibility in this application, although both loadings did show a higher biocompatibility than the bacterial cellulose on its own. The research also found that it was possible to achieve a higher ibuprofen loading on the GO composite material, even in the lower graphene oxide content nanocomposite.

This research has illustrated multiple benefits to forming nanocomposites of graphene oxide and bacterial cellulose for use as drug carriers. It has provided yet another example of the diversity of research which graphene oxide is currently being investigated in. If you are considering using graphene oxide in your research, please get in touch and a member of the team will be happy to discuss which form of graphene oxide they think would be most appropriate for your research.

Reference: Curr. Appl. Phys. 2017, 17, 249-254