Hogweed turned into carbon material for electrodes
29 Aug 2019
Hogweed is being put to use to manufacture electrodes for supercapacitors.
A team at MISIS in Moscow have demonstrated a processing technique that turns fibrous substances from the stems of the plant – which is abundant across vast parts of Russia – into synthesised carbon material for electrodes.
Oleg Levin at the Department of Electrochemistry of St. Petersburg State University said: “The capacity obtained from hogweed stems is at the same level [as that] obtained from other materials.
“Of course, when using, for example, graphene, it will be higher. However, the use of plant waste material for the production of active carbon is without a doubt a global trend.”
Hogweed stems consist of a firm bark and a soft inner core. Hogweed sap is phototoxic and on contact with humans causes phytophotodermatitis, a skin inflammation.
To process the dangerous plant material, the team MISIS cut dry stalks of the hogweed into centimetre bars, which they treated with hydrochloric acid to remove inorganic compounds.
To obtain a carbon material from the hogweed, the bars were then washed, dried, crushed, saturated with CO2 at 400°C and mixed with potassium hydroxide.
Processing the primary carbon material at 900°C led to the formation of a surface with a large of pores between 2-4 nanometres in size – which are needed in electrodes to provide an increased surface area.
Scientists globally are trying to develop carbon materials from plant raw materials, especially from agricultural waste such as nut shells. Their potential uses range from electronic, electromagnetic, electrochemical, to environmental and biomedical.
Professor Mikhail Astakhov, leader of the project and head of Physical Chemistry at MISIS, co-authored a research paper on the technique, published in June.