Suite of Photo-electrochemical Technologies for Hydrogen Production
The primary fuel powering new fuel cell technologies is hydrogen. The market for fuel cells is expected to grow tremendously in the near-term as vehicle manufacturers start mass-production of fuel cell vehicles. As the market for fuel cells grows, so too does demand for hydrogen to supply the fuel cells. The two biggest obstacles in the way of hydrogen production are high cost and storage of product.
While there are multiple methods of hydrogen production, photo-electrochemical (PEC) production may be one of the most promising. PEC production of hydrogen uses the sun’s energy and photo-electrodes to split water into oxygen and hydrogen. The National Renewable Energy Laboratory has developed a portfolio of intellectual property providing optimized hydrogen production in addition to storage solutions that are currently available for licensing.
National Renewable Energy Laboratory- PEC semiconductor fortification via Ion Implantation
- NREL scientists have developed a process for making photo-electrodes that have demonstrated greater than 12% solar to hydrogen efficiency using existing semiconductor manufacturing processes. These photo-electrodes have been tested to over 100 hours with no measurable depletion of material. The photo-electrodes utilize ion implantation and noble metal sputtering on the semiconductor surface. The two surfaces consist of a photovoltaic p/n-GaAs bottom cell and a p-GaInP2 top cell. Surface nitridation of p-GaInP2 is 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 is an innovative improvement in PEC production of hydrogen.
- Intellectual Property: US provisional patent application 61/822,744.
- To learn more, please see: http://techportal.eere.energy.gov/technology.do/techID=1076
National Renewable Energy Laboratory- Improved semiconductor electrode for photo-electrochemistry
- NREL scientists have developed a semiconductor photo-electrode which utilizes a nanostructured, anti-reflective (AR) surface to substantially improve solar to hydrogen efficiency. Nanostructured semiconductors used in the invention have optical properties of a density graded surface that can suppress reflection well below 5% over the entire range of the solar spectrum. The semiconductors with a density-graded surface have a 1-dimensional nanostructure, such as arrays of nanopores and/or nanowires. The density-graded surface on the semiconductor is formed by a chemical etching method which involves a metal catalyst and etching solution. The implementation of this AR surface can improve the efficiency of PEC H2 production by more than 20% compared to a silicon photocathode without an AR surface.
- Intellectual Property: US patent 8,729,798
- To learn more about this technology please visit: http://techportal.eere.energy.gov/technology.do/techID=1186
National Renewable Energy Laboratory- Hydrogen Electrochemical Energy Storage Device
- NREL scientists have designed an electrochemical energy storage device which comprises an electrode made of relatively lightweight materials. The device has a flexible design which allows for a variety of counter electrode and ion-exchange membrane materials. One of the key aspects of this design is the unique hydrogen storage mechanism that enables hydrogen atoms or di-hydrogen molecules to be stored and also conducted so that they may participate in electrochemical processes. Unlike metal hydrides or chemical hydrides, which are typically used to store hydrogen, this design uses relatively "inert" lightweight materials where the hydrogen is stored on the electrode materials with a substantially weaker binding than is typically the case. This "weaker" binding is sufficient to store substantial amounts of hydrogen at ambient temperatures, but also enables the transport and low energy barriers needed for efficient electrochemical processing.
- Intellectual Property: US patent 8,501,349
- To learn more, please see: http://techportal.eere.energy.gov/technology.do/techID=1107
- Storage and electrochemical processes in single device
- Higher efficiency and more durable photo-electrodes
- Anti-reflective coating through etching
Patents and Patent Applications
|Title and Abstract||
Hydrogen-based electrochemical energy storage
An energy storage device (100) providing high storage densities via hydrogen storage. The device (100) includes a counter electrode (110), a storage electrode (130), and an ion conducting membrane (120) positioned between the counter electrode (110) and the storage electrode (130). The counter electrode (110) is formed of one or more materials with an affinity for hydrogen and includes an exchange matrix for elements/materials selected from the non-noble materials that have an affinity for hydrogen. The storage electrode (130) is loaded with hydrogen such as atomic or mono-hydrogen that is adsorbed by a hydrogen storage material such that the hydrogen (132, 134) may be stored with low chemical bonding. The hydrogen storage material is typically formed of a lightweight material such as carbon or boron with a network of passage-ways or intercalants for storing and conducting mono-hydrogen, protons, or the like. The hydrogen storage material may store at least ten percent by weight hydrogen (132, 134) at ambient temperature and pressure.
|National Renewable Energy Laboratory||08/06/2013
Anti-reflective nanoporous silicon for efficient hydrogen production
Exemplary embodiments are disclosed of anti-reflective nanoporous silicon for efficient hydrogen production by photoelectrolysis of water. A nanoporous black Si is disclosed as an efficient photocathode for H.sub.2 production from water splitting half-reaction.
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