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Hydrogen sorption kinetics on bare and platinum-modified palladium nanofilms, grown by electrochemical atomic layer deposition (E-ALD)

Journal of the Electrochemical Society

Jagannathan, Kaushik; Benson, David M.; Robinson, David R.; Stickney, John L.

Nanofilms of Pd were grown using an electrochemical form of atomic layer deposition (E-ALD) on 100 nm evaporated Au films on glass. Multiple cycles of surface-limited redox replacement (SLRR) were used to grow deposits. Each SLRR involved the underpotential deposition (UPD) of a Cu atomic layer, followed by open circuit replacement via redox exchange with tetrachloropalladate, forming a Pd atomic layer: one E-ALD deposition cycle. That cycle was repeated in order to grow deposits of a desired thickness. 5 cycles of Pd deposition were performed on the Au on glass substrates, resulting in the formation of 2.5 monolayers of Pd. Those Pd films were then modified with varying coverages of Pt, also formed using SLRR. The amount of Pt was controlled by changing the potential for Cu UPD, and by increasing the number of Pt deposition cycles. Hydrogen absorption was studied using coulometry and cyclic voltammetry in 0.1 M H2SO4 as a function of Pt coverage. The presence of even a small fraction of a Pt monolayer dramatically increased the rate of hydrogen desorption. However, this did not reduce the films' hydrogen storage capacity. The increase in desorption rate in the presence of Pt was over an order of magnitude.

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TYPE Journal Article YEAR 2016
ScopusOSTIDOI

In-situ 3D characterization of He bubble and displacement damage in dense and nanoporous thin films

Hattar, Khalid M.; Robinson, David R.

This initial work attempted to determine the feasibility of using advanced in-situ, electron tomography, and precession electron diffraction techniques to determine the structural evolution that occurs during advanced aging of Pd films with nanometer resolution. To date, significant progress has been made in studying the cavity structures in sputtered, evaporated, and pulsed-laser deposited Pd films that result from both the deposition parameters, as well as from He ion implantation. In addition, preliminary work has been done to determine the feasibility of performing precession electron diffraction (PED) and electron tomography in these type of systems. Significant future work is needed to determine the proper conditions such that relevant advanced aging protocols can be developed.

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TYPE Other Report YEAR 2015
OSTIDOI

Hydrogen isotope MicroChemLab FY15

Robinson, David R.; Luo, Weifang L.; Stewart, Kenneth D.

We have developed a new method to measure the composition of gaseous mixtures of any two hydrogen isotopes, as well as an inert gas component. When tritium is one of those hydrogen isotopes, there is usually some helium present, because the tritium decays to form helium at a rate of about 1% every 2 months. The usual way of measuring composition of these mixtures involves mass spectrometry, which involves bulky, energy-intensive, expensive instruments, including vacuum pumps that can quite undesirably disperse tritium. Our approach uses calorimetry of a small quantity of hydrogen-absorbing material to determine gas composition without consuming or dispersing the analytes. Our work was a proof of principle using a rather large and slow benchtop calorimeter. Incorporation of microfabricated calorimeters, such as those that have been developed in Sandia’s MicroChemLab program or that are now commercially available, would allow for faster measurements and a smaller instrument footprint.

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TYPE Other Report YEAR 2015
OSTIDOI

Composite WO3/TiO2 nanostructures for high electrochromic activity

ACS Applied Materials and Interfaces

Reyes, Karla R.; Stephens, Zachary D.; Robinson, David R.

A composite material consisting of TiO2 nanotubes (NT) with WO3 electrodeposited on its surface has been fabricated, detached from its Ti substrate, and attached to a fluorine-doped tin oxide (FTO) film on glass for application to electrochromic (EC) reactions. Several adhesion layers were tested, finding that a paste of TiO2 made from commercially available TiO2 nanoparticles creates an interface for the TiO2 NT film to attach to the FTO glass, which is conductive and does not cause solution-phase ions in an electrolyte to bind irreversibly with the material. The effect of NT length and WO3 concentration on the EC performance were studied. As a result, the composite WO3/TiO2 nanostructures showed higher ion storage capacity, better stability, enhanced EC contrast, and longer memory time compared with the pure WO3 and TiO2 materials

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TYPE Journal Article YEAR 2015
OSTIDOI
Results 51–75 of 154
Results 51–75 of 154