Original data from the first ever paper on graphene oxide, by Brodie.
The history of graphene oxide (GO), like many other novel materials, begins with its unintended discovery. Though there is a gap of about 150 years between its creation and its renewed interest, graphene oxide is perhaps one of the most unique substances ever researched. Starting from its first synthesis in in the lab to its modern day capability for practical application ranging from radioactive waste cleanup to quantum dots, the story of this wondrous material begins in a single lab.
B.C. Brodie was a professor at the University of Oxford in 1859 who was attempting to find the molecular weight of graphite. Having noticed that graphite had very different properties than other forms of carbon such as diamond or charcoal, Brodie had hypothesized that graphite was a unique element and therefore decided that the best method was to oxidize the graphite and then to perform elemental analysis, since he already knew the molecular weights of hydrogen and oxygen: graphite would be the missing piece of his puzzle.
However, Brodie knew that graphite was unreactive with strong oxidizers, as even submerging it in boiling sulfuric acid would result in no reaction, eliciting his usage of extremely strong chemicals. Therefore, after using a mixture of potassium chlorate, fuming nitric acid, and heating, Brodie observed that the dull grey graphite had gained weight and taken on a light yellow color. Upon weighing the substance, Brodie also noticed that the substance had gained weight from the original graphite used: an indication of oxidization.
At this point, Brodie set off to analyze his product and quickly noticed that it was divided into seemingly smaller flakes, which he deemed to be crystals. Though his observation through a light microscope, he made an observation that would be significant even today: noticing that “the crystals are so extremely thin in a direction perpendicular to the paper … that it is impossible to obtain any reflection” (251). Though he was observing a thin, dried film rather than a suspension, this is perhaps one of the first times a near-atom thick substance was observed by a human being.
Brodie reduces graphene oxide through thermal means.
Having no luck from optical observation, Brodie resorted to combusting it in order to discover what elements it contained. Luckily, he managed to determine it contained only carbon, oxygen, and hydrogen in the forms of carbonic acid and water, with a carbon:oxygen ratio of 11:6. Interestingly enough, it did not contain a detectable amount of nitrogen or chlorine, which was found in the original reagents. Upon ignition, Brodie also observed that the graphene oxide would “explode” into a black powder: the first ever reduction of graphene oxide ever performed .
Though Brodie’s conclusion that graphite was a unique element was eventually proven to be wrong, his lengthy observations and studies into the synthesis of graphene oxide offer us valuable insight in its physical and chemical properties. However, there was still one major issue: Brodie’s synthesis method involved chemicals that were extremely dangerous and prone to explosion, which would only be exacerbated by his addition of heat. It was only a century later, in 1957, when W. Hummers and R. Offeman would develop a safer method of oxidation.
Hummers and Offeman also used a method that involved extremely strong oxidizers: potassium permanganate, sodium nitrate, and sulfuric acid. However, their method used fewer reagents and had no water: allowing for both a speedier and safer synthesis, as well as producing a product with a slightly higher ratio of oxidation at 2.1 carbon atoms with every 1 oxygen atoms. Modern scientists still use a modified version of Hummer’s method, showing how Brodie, Hummers, and Offemans’ studies have ultimately been the root of thousands of studies of graphene oxide across a multitude of industries .
Today, graphene oxide has the potential to open thousands of doors of human potential. As we continue to research and streamline the process to create graphene oxide, we hope that our research will allow us to bring various graphene oxide applications into reality.
- On the Atomic Weight of Graphite
B. C. Brodie
Philosophical Transactions of the Royal Society of London, Vol. 149, (1859), pp. 249-259
Published by: The Royal Society
Article Stable URL: http://www.jstor.org/stable/108699
- DOI: 10.1021/ja01539a017
There actually were only two notable papers during the history of graphene oxide; this is probably because:
- Graphene oxide wasn’t created to be used, it was accidently created when Brodie tried to provide graphite was an element
- The technology to utilize graphene oxide has only been recently discovered (last decade)
- Graphene oxide mainly gained attention due to the graphene hype, which only started in the last few years as well