Additive Manufacturing of Graphene-based Devices

Abstract

Additive manufacturing (AM) introduces a new era for the fabrication of 3D structures. AM, as an emerging and disruptive manufacturing technology, has the potential to be employed for fabrication of polymeric, metallic, and ceramic structures. Although AM is now being used for commercial applications, there are still many challenges in incorporating high-performance materials into these techniques and employing them to fabricate practical devices. For instance, reduced graphene oxide (RGO) has interesting properties such as high specific surface area and lattice defects with tunable functional groups which make it ideal for different applications. However, there is still a substantial need to introduce reliable manufacturing techniques for RGO-based devices while attaining the utmost performance of graphene-based materials. In this study, a binder-jetting powder-bed AM technique has been employed to fabricate graphene-based structures and devices for energy storage and sensing applications. First, 3D structures of graphene/hydroxyapatite (Hap) based composite with potential applications in bone-implantation were fabricated using AM technique. Hap suffers from lack of sufficient mechanical strength which has limited its application for practical use. The compressive strength of the 3D printed structures were tested and the printing parameters were optimized to improve the mechanical behavior of the specimens. It was shown that at a layer thickness of 125 μm and core binder saturation level of 400%, the mechanical strength of HG4 structures with only 0.4 wt.% of graphene oxide were 70 times more than that of HG0 structures. Our next goal was to print pure graphene-based structures for energy and sensing applications. Hence, graphene oxide was first synthesized through Hummer’s method and then reduced it through thermal and chemical methods to compare their performance for energy applications. The as-obtained thermally and chemically reduced graphene-oxide based powder were both 3D printed and studied accordingly. It was revealed that the gravimetric capacitance of thermally reduced graphene oxide (TRGO) 3D printed electrodes were 3-4 times higher than that of chemically reduced powder. Therefore, TRGO powder was selected for further studies and optimization. In order to improve the performance of 3D printed TRGO based electrodes, a nano palladium dispersion was synthesized and injected into the electrodes after printing. TRGO based decorated with nano palladium particles showed an impressive capacitance of 265 F/g and 700 mF/cm2 at 5 mV/s. This study can introduce a new potential application of AM for the fabrication of graphene-based supercapacitor devices. In addition, a graphene-based humidity sensing devices was also fabricated using powder-bed AM technique. The results obtained from this device were promising and demonstrated a great potential for the use of AM for manufacturing of graphene-based sensor devices.