Electromechanical Actuators Based on Graphene and Graphene/Fe3O4 Hybrid Paper

Exceptionally high specific 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 flexible graphene-based paper prepared via a filtration 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, Fe3O4 nanoparticles were used to partially prevent graphene sheets from restacking and allow the electrolyte ions to infiltrate 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.