Mechanically Assisted Exfoliation and Functionalization of Thermally Converted Graphene Sheets

Published versio

Longitudinal unzipping of carbon nanotubes to form graphene nanoribbons.

Published versio

In-situ electronic characterization of graphene nanoconstrictions fabricated in a transmission electron microscope

We report electronic measurements on high-quality graphene nanoconstrictions (GNCs) fabricated in a transmission electron microscope (TEM), and the first measurements on GNC conductance with an accurate measurement of constriction width down to 1 nm. To create the GNCs, freely-suspended graphene ribbons were fabricated using few-layer graphene grown by chemical vapor deposition. The ribbons were loaded into the TEM, and a current-annealing procedure was used to clean the material and improve its electronic characteristics. The TEM beam was then used to sculpt GNCs to a series of desired widths in the range 1 - 700 nm; after each sculpting step, the sample was imaged by TEM and its electronic properties measured in-situ. GNC conductance was found to be remarkably high, comparable to that of exfoliated graphene samples of similar size. The GNC conductance varied with width approximately as, where w is the constriction width in nanometers. GNCs support current densities greater than 120 \muA/nm2, two orders of magnitude higher than has been previously reported for graphene nanoribbons and 2000 times higher than copper.Comment: 17 pages, 4 figures. Accepted by Nano Letter

Exergy analysis and energy utilization in the transportation sector of the Philippines

This paper analysed the energy and exergy utilization of the four transportation sectors (road, rail, water, and air) in the Philippines during the years 1990 to 2016. The consumption per fuel was also considered in the analysis because each sector utilizes one or more type of fuel. The collected data showed that road transportation has the highest fuel utilization, and energy and exergy efficiency amongst the four followed by the aviation and marine subsectors which are both less significant than the results from the road transportation sector. Also, it was observed that diesel and gasoline are the ones commonly used in the road, rail, and marine subsectors compared to LPG, ethanol, biodiesel, and electricity. Comparing the overall energy and exergy efficiencies from 20 years ago, it was observed that the efficiencies are gradually increasing annually in small increments. The data presented in this research will be beneficial to the Philippine transportation sector to effectively reduce cost and improve the quality of transport in the country. It is also helpful to base future transportation designs on the energy and exergy efficiencies to better improve transportation and reduce the environmental impact which can both be practical for the economy and the ecosystem. © 2020 IOP Publishing Ltd