Large-Scale Direct Patterning of Aligned Single-Walled Carbon Nanotube Arrays Using Dip-Pen Nanolithography

The strength of dip-pen nanolithography (DPN) is the ability to create nano- or microarrays of organic compounds and nanomaterials in a nondestructive and direct-write manner. However, transporting large-sized ink materials, such as carbon nanotubes (CNTs), has been a significant challenge. We report a direct-write patterning of aligned single-walled carbon nanotube (SWNT) arrays on silicon oxide using DPN. The patterned SWNT arrays show a high degree of alignment and controllable width ranging from 2 μm down to 8 nm. Furthermore, field-effect transistors based on these SWNT arrays show p-type characteristic. High-throughput patterning of the aligned SWNTs over a large area was also achieved via polymer pen lithography (PPL). The reported technique will further expand the application of SWNTs to diverse nanoelectronic devices

Vertical Alignments of Graphene Sheets Spatially and Densely Piled for Fast Ion Diffusion in Compact Supercapacitors

Supercapacitors with porous carbon structures have high energy storage capacity. However, the porous nature of the carbon electrode, composed mainly of carbon nanotubes (CNTs) and graphene oxide (GO) derivatives, negatively impacts the volumetric electrochemical characteristics of the supercapacitors because of poor packing density (<0.5 g cm^–3). Herein, we report a simple method to fabricate highly dense and vertically aligned reduced graphene oxide (VArGO) electrodes involving simple hand-rolling and cutting processes. Because of their vertically aligned and opened-edge graphene structure, VArGO electrodes displayed high packing density and highly efficient volumetric and areal electrochemical characteristics, very fast electrolyte ion diffusion with rectangular CV curves even at a high scan rate (20 V/s), and the highest volumetric capacitance among known rGO electrodes. Surprisingly, even when the film thickness of the VArGO electrode was increased, its volumetric and areal capacitances were maintained