Exceptionally high specifi c surface area, mechanical strength, electrical
conductivity, and a special two-dimensional structure make graphene a
highly promising material for electromechanical actuators. Electromechanical
actuators are fabricated using fl exible graphene-based paper prepared via a
fi ltration process, and the stroke of these graphene-based actuators is directly
measured during electrochemical double-layer charge injection. Actuation
strain up to 0.064% was obtained for pristine graphene paper in response to
an applied potential of –1 V in 1 M NaCl solution. Double-layer charge injection
in graphene sheets is believed to induce actuation strain through a combination
of coulombic and quantum-chemical-based expansion. To increase
electrochemical-double-layer capacitance and actuator performance, Fe 3 O 4
nanoparticles were used to partially prevent graphene sheets from restacking
and allow the electrolyte ions to infi ltrate the resulting magnetic graphene
paper more easily. The magnetic graphene paper exhibits actuation strain as
large as 0.1% at –1 V applied potential, which is about 56% higher than that
of the pristine graphene paper.
