Photoelectrochemical Semiconductor Surface Fortification via Ion Implantation
Producing hydrogen from clean sources of energy has been one of the major challenges of hydrogen production. While production from fossil fuel processes has been the norm, one of the most promising clean technologies has been hydrogen production through photo-electrochemical (PEC) cells. The three main hurdles of PEC hydrogen production have been efficiency, durability, and cost of production. The U.S. Department of Energy (DOE) reports that for photo-electrochemical water splitting to be economical, solar to hydrogen efficiency must reach at least 10% for 1000+ hours.
PEC production of hydrogen works by using the sun’s energy and photo-electrodes. The sun shines on the photo-electrodes in an aqueous solution. This in turn creates an electric current which drives the water splitting processes to produce hydrogen and oxygen. The produced hydrogen can currently be used in a variety of applications including metal processing, electronics manufacturing, aerospace and others. Developing markets for hydrogen include fuel cells, transportation, and other power generation.
The market for hydrogen has been growing consistently. U.S. fuel cell shipments quadrupled between 2008 and 2010. The small-industrial market for hydrogen is about 300,000 kg/day and while fuel prices vary, mainly varying per transportation method and purity, it is estimated that the small-industrial hydrogen market ranges between $1-2 billion/year and expected to grow at a CAGR of 6.5% through 2016.Description
NREL scientists have developed a process for making photo-electrodes that have demonstrated greater than 12% solar to hydrogen efficiency. These photo-electrodes have been tested to over 100 hours with no measurable depletion of material.
This was developed through ion implantation and noble metal sputtering of the semiconductor surface. The two surfaces consisted of a photovoltaic p/n-GaAs bottom cell and a p-GaInP2 top cell. Surface nitridation of p-GaInP2 was done by bombardment with low-energy N2+ ions at room temperature. The second process involves sputtering very small amounts of a PtRu alloy on the surface of the semiconductor. These two processes are commonly used in semiconductor processing, but this combination and application to a semiconductor surface for photo-electrolysis hasn’t been demonstrated before.
NREL scientists have shown that two common manufacturing processes applied to photo-electrodes increase the efficiency and durability of a PEC system to viable levels where economic hydrogen could be produced. The technology is ready for further development and manufacturing design.Benefits
More durable photo-electrodes, higher efficiency photo-electrodes, higher efficiency photo-electrochemical production of hydrogen, decreased hydrogen production costsApplications and Industries
Energy storage, electric vehicles, hydrogen production, fuel cellsPatents and Patent Applications
|Title and Abstract||
STABLE PHOTOELECTRODE SURFACES AND METHODS
Disclosed herein are methods of treating a semiconductor surface by nitridation and deposition of a ruthenium alloy. Also disclosed are semiconductors treated with these methods, their incorporation into photoelectrochemical cells, and their use in photoelectrochemical water splitting.
|National Renewable Energy Laboratory||05/13/2014
|Technology ID||Development Stage||Availability||Published||Last Updated|