Students: Chia-Jung Chung
In order for the transition to a hydrogen-based economy to become feasible and economically practical, many material challenges must be met. Not the least of these is the engineering of a hydrogen storage material with high storage density (both gravimetric and volumetric), appropriate equilibrium pressure, favorable reaction kinetics, relative safety and low cost. Metal hydrides represent one attractive way to store large amounts of hydrogen due to the very high potential volumetric capacity which can even exceed that of liquid hydrogen. So far, however, no single material has met all the requirements needed for a practical, reversible on-board storage material.
We combine the flexibility and control of physical vapor deposition to fabricate thin film samples with precise chemical compositions and microstructures in order to probe metal hydride reactions in a very controlled way. Using a variety of thin film and powder characterization techniques (from x-ray diffraction to quartz crystal microbalance measurements and gas adsorption in a Sievert’s type apparatus) we monitor the thermodynamic, kinetic and structural properties of these materials in order to gain a more fundamental understanding about the processes limiting their practical implementations. By applying the knowledge learned from these highly controlled systems we can engineer materials to better meet the challenge of a hydrogen based economy.
Our research focuses on metal hydride materials and carbon nanotube-based materials for hydrogen storage and we collaborate with other institutions, working at Stanford as well as NASA Ames Research Center and the Stanford Synchrotron Radiation Lightsource.