Graphene: stackable when wet

A quick one to add to the list of fun facts about graphene: if you want to stack it in layers to make a supercapacitor, you’d do well to keep it wet. This fun fact has been brought to our attention by the good people of Monash University in Australia.

Dan Li and colleagues have found that keeping layers of chemically derived graphene wet prevents them from forming a "solid, graphite-like mass", according to Nanowerk.com, which is otherwise what tends to happen when you try to stack layers of the two dimensional material.

The research, which is published in the journal Advanced Materials focused on chemically derived graphene sheets. These are corrugated rather than being perfectly flat. Li suggests that when they are stacked, this quality means they have less contact with each other than flat sheets. Adding water adds enough repulsion to keep the sheets apart, the Australian team discovered.

Per Nanowerk: Li and his colleagues characterized the electrochemical response of supercapacitors constructed using their wet graphene films and observed a much higher capacitance that in the case of dried films. This enhanced capacitance was obtained even at very high frequency, meaning that the charging and discharging of the capacitor can occur at very high speed. Applications [that could] benefit from this bulk assembly [include] battery electrodes, fuel cells, electrochemical sensors and actuators, water purification membranes and even biomedical devices.