Oxygen-Assisted Trimming Growth of Ultrahigh Vertical Graphene Films in a PECVD Process for Superior Energy Storage

Combining the advantages of a three-dimensional structure with intrinsic properties of graphene, vertical graphene (VG) synthesized by the plasma-enhanced chemical vapor deposition (PECVD) process has shown great promise to be applied to energy-storage electrodes. However, the practical application of the VG electrodes suffers from the limited height, which is mostly in a scale of few hundreds of nanometers, as shown in the previous studies. The reason for the unacceptable thin VG film deposition is believed to be the height saturation, stemming from the inevitable confluence of the VG flakes along with the deposition time. In this study, we developed an oxygen-assisted "trimming" process to eliminate the overfrondent graphene nanosheets thereby surmounting the saturation of the VG thickness during growth. In this approach, the height of the VGs reaches as high as 80 μm. Tested as supercapacitor electrodes, a desirable capacitance of 241.35 mF cm^-2 is obtained by the VG films, indicating the superior electrochemical properties and the potential for applications in energy storage. It is worth noting, this thickness is by no means the maximum that can be achieved with our synthesis technique and higher capacitance can be achieved by conducting the circulating deposition-correction process in our work.