|The solar hydrogen filling station|
A research consortium led by the University of Nevada Las Vegas Research Foundation (UNLVRF) and including Altair Nanotechnologies and Hydrogen Solar has received an additional $2.5 million Phase III grant award from the US Department of Energy (DOE) to further the development of solar hydrogen generation cells.
Under the terms of the grant, UNLVRF, a non-profit affiliate of UNLV, is leading a team in multiple projects to research and to develop solar hydrogen technologies, including the development of a solar hydrogen filing station.
In the initial phases of the project, which received $3 million in funding last year, Hydrogen Solar and Altair undertook research and product development to further raise the performance of Hydrogen Solar’s Tandem Cell (earlier post). The Tandem cell generates hydrogen directly from sunlight and water.
|Schematic of the Tandem Cell|
The Tandem Cell consists of two photo-catalytic cells in series. The front cell has glass walls and contains a water-based electrolyte. The photocatalytic nanocrystalline film is on the rear wall of the cell on conducting glass.
The front cell absorbs the high energy ultraviolet and blue light in sunlight, using nano-crystalline metal oxide thin films to generate electron-hole pairs. There is not quite enough voltage difference in the first type of cell to spilt water, so the Tandem Cell uses a second cell, a Grätzel cell.
The longer wavelength light in the green-to-red region passes through the front cell and is absorbed by the Grätzel Cell, which produces electrical potential under nearly all light conditions. This boosts the energy of the electrons which then come back to a hydrogen electrode in the front cell.
Hydrogen Solar developed the photo-catalytic nano-crystalline thin films in the cells. Altair Nanotechnologies is using its nanomaterials synthesis technology to develop low-cost processing for and to further improve the performance of the thin-film electrode in the front section of the Tandem Cell. Altair’s efforts include a focus on iron oxide-based materials and development of film deposition methods and synthesis routes for the optimized metal oxide nanomaterials.
Under Phase III, Task IV of the new grant, Altairnano is charged with enhancing the electrode materials to increase the photoelectrodes’ current density, and developing a flexible conducting substrate material for scaling up the electrodes.
Altairnano, which is a ceramic nanomaterials manufacturer, recently accelerated its efforts to develop nano-structured battery electrode materials and to manufacture in-house prototype lithium-ion cells, batteries and battery packs. (Earlier post.) The company is looking into combining its nano titanate spinel electrode materials (earlier post) with other materials that utilize manganese or iron phosphate (as compared to other batteries containing lead, acid, cobalt, cadmium, nickel and so on).