Thomas Gennett

Rapid, Room Temperature, High-Density Hydrogen Adsorption on Single-Walled Carbon Nanotubes at Atmospheric Pressure Assisted by a Metal Alloy

Laser-generated, carbon single-walled nanotubes (SWNTs) adsorb hydrogen in a matter of minutes at room temperature and atmospheric pressure in the presence of a Ti-6Al-4V metal alloy. The unusual hydrogen adsorption properties are activated when the SWNTs are sonicated in nitric acid with a Ti-6Al-4V probe. The process cuts the SWNTs and introduces ∼15-40 wt% metal alloy into the previously pure single-walled nanotube material. Subsequent hydrogen adsorption occurs in two separate sites with a maximum adsorption capacity of ∼7 wt% on a total sample weight basis. Approximately 2.5 wt% hydrogen is evolved at 300 K while the remainder desorbs between 475-850 K. The pure metal alloy adsorbs ∼ 2.5 wt% H 2 , and evolvesydrogen with increasing temperature in a manner similar to the alloy-doped SWNTs. However, it is clear from studies presented here that the SWNT fraction is quite active in H 2 uptake, adsorbing as much as 7 % on a SWNT weight basis.

The Influence of Surfaces and Deposition Processes on Pt Structure and Properties

Transparent conductive oxides (TCOs), In-Zn-O (IZO) and Ga-Zn-O (GZO), on glass are used as model substrates to study the effect of surface treatments and deposition processes on Pt growth and nanostructure. The TCO type and surface treatments appear to affect Pt nucleation and growth. Ar and O2 plasma surface treatments significantly lowered the contact angle of water measured on TCOs compared to trimethylaluminum surface treatment and samples without surface treatment. Annealing TCO samples in oxygen resulted in lower IZO conductivity and higher contact angle; while annealing in vacuum or hydrogen resulted in increased carbon on the surface, which appears to be related to higher water contact angles and higher conductivity. Higher amounts of zinc and carbon (probably due to contamination from the annealing chamber) on the IZO surface seem to correlate with lower water contact angles and lower conductivity.