Classical Values :: A New Kind Of Solar Cell

August 01, 2008

A New Kind Of Solar Cell

The boffins are at it again They have just invented a new kind of solar cell that produces hydrogen from salt water.

In Situ Formation of an Oxygen-Evolving Catalyst in Neutral Water Containing Phosphate and Co2+

Matthew W. Kanan 1 and Daniel G. Nocera 1*

The utilization of solar energy on a large scale requires its storage. In natural photosynthesis, energy from sunlight is used to rearrange the bonds of water to O2 and H2-equivalents. The realization of artificial systems that perform similar "water splitting" requires catalysts that produce O2 from water without the need for excessive driving potentials. Here, we report such a catalyst that forms upon the oxidative polarization of an inert indium tin oxide electrode in phosphate-buffered water containing Co²⁺. A variety of analytical techniques indicates the presence of phosphate in an approximate 1:2 ratio with cobalt in this material. The pH dependence of the catalytic activity also implicates HPO₄^2- as the proton acceptor in the O2- producing reaction. This catalyst not only forms in situ from earth-abundant materials but also operates in neutral water under ambient conditions.

There are two possible flies in this ointment.

Indium is not abundant.

Efficiency.

It will be interesting to see if this can be manufactured at a reasonable cost.

The New York Times has more.

H/T Just One Minute

Cross Posted at Power and Control

Update 02 Aug 008 1415z

Commenter Bill Woods tells me that this is not a solar cell but a more efficient way to separate hydrogen from oxygen. He is right.

posted by Simon on 08.01.08 at 01:10 PM

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Comments

I'm still a fan of the idea (I'm happy this has been talked about a bit). I was talking it up a few years ago when I realized that chemical storage is probably the way to go do to higher energy densities. The solar part makes it renewable as one's gonna get.

As to the idium part, to be fair, it's a catalyst. It doesn;t get used up. As to the efficiency.. well.. there's very little outside energy input once the system's up. This is a long term solution (although I think nuclear is the midterm one) as the hydrogen gets recycled back into water during the combustion. In an odd way, it's like a steam cycle.

bellisaurius · August 1, 2008 07:34 PM

No, it's not a new kind of solar cell. It's a new kind of electrolysis, which might make it cost-effective to store electricity — if it pans out. Take electricity generated any old how, break water (H2O) into H2 and O, then later run the gases (H2 and O2) through a fuel cell to get back X% of your electricity.

This is being billed as a way to exploit solar power, but it seems to me that solar power matches peak demand tolerably well anyway. If you can make it, just sell it or use it.

Wind power would benefit at least as much, since this would provide a way to turn an intermittent power supply into something more reliable. And nuclear (and coal) plants could run full blast during the night, storing up power for the next day's peak demand.

Bill Woods · August 2, 2008 02:51 AM

Unless there are MAJOR reductions in fuel cell costs, then the reconversion of the hydrogen to electricity needs to be done in some other way. Maybe a small turbine for residential installations, or a combined gas/steam cycle for larger facilies. Yes, it's less efficient than a fuel cell, but I bet on a cost basis, it still comes out ahead.

david foster · August 2, 2008 11:36 AM