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New Way to Split Water Molecules Into Hydrogen and Oxygen: Breakthrough for Solar Energy Conversion and Storage?

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November 12, 2012 – Comments (5)

Apologies for the multiple posts today, but this is another really good one. This idea has been around and in fact Dr. Dan Nocera from MIT has already made large advancements with it (see: The first practical artifical leaf) and his system already uses low cost materials. But this approach below uses a different set of materials that will offer different advantages. And it makes me very excited to see developments like this.

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New Way to Split Water Molecules Into Hydrogen and Oxygen: Breakthrough for Solar Energy Conversion and Storage?
http://www.sciencedaily.com/releases/2012/11/121112095943.htm


ScienceDaily (Nov. 12, 2012) — Using the power of the sun and ultrathin films of iron oxide (commonly known as rust), Technion-Israel Institute of Technology researchers have found a novel way to split water molecules into hydrogen and oxygen. The breakthrough, published this week in Nature Materials, could lead to less expensive, more efficient ways to store solar energy in the form of hydrogen-based fuels. This could be a major step forward in the development of viable replacements for fossil fuels.

“Our approach is the first of its kind,” says lead researcher Associate Prof. Avner Rothschild, of the Department of Materials Science and Engineering. “We have found a way to trap light in ultrathin films of iron oxide that are 5,000 times thinner than typical office paper. This is the enabling key to achieving high efficiency and low cost. ”

Iron oxide is a common semiconductor material, inexpensive to produce, stable in water, and – unlike other semiconductors such as silicon – can oxidize water without itself being oxidated, corroded, or decomposed. But it also presents challenges, the greatest of which was finding a way to overcome its poor electrical transport properties. Researchers have struggled for years with the tradeoff between light absorption and the separation and collection of photogenerated charge carriers before they die out by recombination.

“Our light-trapping scheme overcomes this tradeoff, enabling efficient absorption in ultrathin films wherein the photogenerated charge carriers are collected efficiently,” says Prof. Rothschild. “The light is trapped in quarter-wave or even deeper sub-wavelength films on mirror-like back reflector substrates. Interference between forward- and backward-propagating waves enhances the light absorption close to the surface, and the photogenerated charge carriers are collected before they die off."

The breakthrough could make possible the design of inexpensive solar cells that combine ultrathin iron oxide photoelectrodes with conventional photovoltaic cells based on silicon or other materials to produce electricity and hydrogen. According to Prof. Rothschild, these cells could store solar energy for on demand use, 24 hours per day. This is in strong contrast to conventional photovoltaic cells, which provide power only when the sun is shining (and not at night or when it is cloudy).

5 Comments – Post Your Own

#1) On November 12, 2012 at 1:34 PM, Melaschasm (56.75) wrote:

This is a really cool development.  If nothing else, it makes hydrogen generators an intriguing option.

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#2) On November 12, 2012 at 2:01 PM, chk999 (99.97) wrote:

The problem with the original idea for hydrogen based transport was that there's no native source of hydrogen. You always had to use other enegy (primarily electrical) to produce it. 

But this could make hydrogen farms on waste land possible and the hydrogen can be stored and transported. Suddenly a hydrogen infrastructure looks a lot more practical.

This could be big. 

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#3) On November 12, 2012 at 2:58 PM, binve (< 20) wrote:

Melaschasm,

Exactly. The power from the sun is free, and the substrate splits the water passively. Combine this will PVs to run pumps, etc. during the day to move water and store the hydrogen this could easily be part of a self-contained remote / distributed power generation plant.

chk999 ,

Exactly. Solar energy is free, and as long as substrates can break the water passively (like Nocera's artifical leaf) then the sun is the only power source you need to do the splitting.

I agree, this could be very big..

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#4) On November 12, 2012 at 5:05 PM, Turfscape (40.91) wrote:

>>But this could make hydrogen farms on waste land possible and the hydrogen can be stored and transported. Suddenly a hydrogen infrastructure looks a lot more practical.<<

Perhaps time to take a second look at companies like Ballard Power Systems or Plug Power?

It really is an exciting development. We're standing at the edge of a potential power and transportation sea-change.

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#5) On November 13, 2012 at 9:08 AM, binve (< 20) wrote:

Turfscape,

Indeed!.

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