A commercially-viable material for use in energy applications, catalysis and environmental clean-up could be one step closer, thanks to researchers in the US.
Graphene is rarely out of the headlines. The single layer of carbon atoms displays remarkable properties, including its superior electrical and thermal conductivity, and mechanical strength. In its native form, graphene has limited utility, so focus has shifted to integrating it into bulk-scale materials, to effectively ‘scale-up’ its properties. One option is graphene aerogels, which show potential for use in a wide range of applications.
The time-consuming manufacturing processes involved in producing these aerogels have historically been a bottleneck to their use in commercial systems, but that may all be about to change. In a paper from the upcoming December issue of Carbon [DOI: 10.1016/j.carbon.2015.08.037], researchers from the Pacific Northwest National Laboratory and the University of Washington have outlined an ultra-fast process for synthesising graphene-oxide (GO) aerogels.
Carbon-based aerogels – often referred to RF aerogels after their main ingredients (resorcinol and formaldehyde) – have been in use since the 1990s. But most depend on a slow, water-based process at elevated temperatures that can take up to 72 hours to complete. Those based on sodium catalysts take even longer to cure – up to seven days at 85°C. Pauzauskie and his team adapted the standard RF approach, using an acid-catalysed route, they produced a graphene-oxide (GO) laden aerogel in just two hours.
Collaborating with an energy storage company, the researchers tested the aerogel’s performance as an electrode for supercapacitors. This work demonstrated that GO-loaded aerogels exhibit a higher capacitance and power capability than RF-aerogels, making them a material of interest for energy storage! As well as analysing the material’s electrochemical properties, the researchers also tested it as a possible sorbent for environmental toxins. Cyclohexane is a precursor for many industrial products – nylon being one of them. It was found that, despite having fewer pores, the GO-aerogels could absorb more than 3 times as much cyclohexane as RF-aerogels. The graphene’s hydrophobic nature was believed to be source of this behaviour.
The team are now focused on finding an alternative, more environmentally-friendly catalyst for the process. They believe that their approach will make it easier, and cheaper, to rapidly produce graphene aerogels on a large scale, and could open the door for their use in energy storage and environmental applications.
M. B. Lim, M. Hu,S. Manandhar, A. Sakshaug, A. Strong, L. Riley, P. J. Pauzauskie - “Ultrafast sol-gel synthesis of graphene aerogel materials” - Carbon (2015) 95, 616-624. DOI: 10.1016/j.carbon.2015.08.037