Three Lawrence Livermore researchers have received the Department of Energy's 2014 Hydrogen Production R&D Award for developing a system that uses sunlight to split water molecules, producing hydrogen.
Shared with collaborators from the National Renewable Energy Laboratory (NREL)and the University of Nevada, Las Vegas (UNLV), the award recognizes the team for its work developing models of photoelectrochemical solar-hydrogen production and corrosion processes. It was presented by the Fuel Cell Technologies Office (FCTO) of DOE's Office of Energy Efficiency and Renewable Energy (EERE) in recognition of FCTO-funded R&D in hydrogen production.
These models have been crucial in the development of corrosion mitigation strategies for high-efficiency devices based on III-V semiconductor materials, offering a viable pathway to meet DOE's ultimate cost targets in renewable hydrogen production.
The Livermore team is made up of Tadashi Ogitsu, Brandon Wood and Woon Ih Choi. The Livermore team used quantum-mechanical models to characterize and optimize photoelectrode surfaces for solar to hydrogen fuel conversion.
To break it down simply, the project team develops materials to produce hydrogen by splitting water molecules, using sunlight as the only source of energy. Effectively, the process combines a photovoltaic (solar-cell) and with water electrolysis, but in a tightly coupled way. The system consists of a water-immersed semiconductor, which absorbs sunlight and generates electricity, and a co-catalyst (such as a platinum nanoparticle) that is dispersed on top of the semiconductor to aid in evolving H2 gas from water.
Ogitsu said the award is tied to a recent Journal of the American Chemical Society paper the team published in which a new type of hydrogen evolution mechanism and a way to optimize device performance was discussed.
For the project, NREL researchers design, assemble, and analyze the performance of photoelectrochemical cells based on carefully grown compound semiconductors of Ga, In and P. However, since these high efficiency devices tend to be prone to photo-corrosion, NREL has also been working with the Livermore and UNLV teams to improve their durability. As an example, the project team recently discovered that certain types of surface treatments such as nitrogen implantation can act in concert with specific cocatalysts to dramatically improve device lifetime.
In addition to modeling the device chemistry itself, the Livermore team plays an integral role in interpreting and analyzing the data from the experimental characterization team, which is led by UNLV. Electrode samples provided by NREL are analyzed at the Advanced Light Source at Lawrence Berkeley National Laboratory using X-ray synchrotron spectroscopy, which offers information about the local surface and interface structure. The Livermore team performs spectroscopy calculations of model surfaces to compare directly to the experiments and identify the key underlying mechanisms of durability improvement.