The oxygen-producing catalyst is quoted as being made "of cobalt metal?, phosphate, and an electrode, placed in water". "When electricity - whether from a photovoltaic cell, a wind turbine or any other source - runs through the electrode, the cobalt and phosphate form a thin film on the electrode, and oxygen gas is produced."
I think in reality, for "catalyst" one should read "electrode". What they have actually done is to develop a new anode (positively charged electrode in an electrolytic cell) for the splitting of water by electrolysis. The solution contains Co2+ cations (not cobalt metal) and HPO4]2- anions . The electrode material consists of indium tin oxide upon which becomes absorbed some "cobalt-phosphate" solid when current is passed through it.
It is said [1,2] that the process "can duplicate the water-splitting reaction that occurs during photosynthesis". Well, O.K., that is what photosynthesis does in essence, and then uses the "hydrogen" part, in the form of protons and electrons, to reduce CO2 to form the polysaccharide component of plants, but this is quite a different kind of catalyst, from the chlorophyll magnesium-porphyrin complex that occurs in nature. Chlorophyll does however release oxygen, accounting for the atmospheric burden of the gas, without which organic, surface life would be impossible.
It sounds very innovative and clever and the photosynthesis angle is a nice explanation to use in layman's terms. However, is it true that the discovery means that "solar energy can now be generated on a massive scale as well as rather cheaply"?
I note that platinum is still presumably involved in the process - for the cathode - which will doubtless prove a problem to recover sufficient quantity of per annum to really make a hole in our energy budget using solar-power. I don't have access to the hard scientific weights and measures involved, otherwise I would work the numbers out. I'll try and get hold of the original paper in "Science" which I can't seem to access from my e-journal system here. I have quoted the abstract of the paper below, which casts a little more light on the subject .
There is a useful article with many comments which I have just found via google .
I think this may be another "solution" where the availability of platinum is the final fence at which the "hydrogen-horse" will fall. Other metals might be used to make the cathode, but none commonly are as efficient as platinum. In fuel-cells too, platinum is the best. Hence, presumably, the final fuel-cell in which the hydrogen and oxygen are combined to make the nocturnal electricity also uses an electrode made of platinum, thus increasing the further burden of demand on this rare metal.
Meanwhile our energy-imperatives, based on fossil-fuels and nuclear, become more pressing.
 "Boffins claim solar energy breakthrough." By Jesse Denzin-Weber. http://www.theinquirer.net/gb/inquirer/news/2008/08/05/major-discovery-field-solar
 "'Major discovery' from MIT primed to unleash solar energy revolution." By Anne Trafton, MIT News Office. http://web.mit.edu/newsoffice/2008/oxygen-0731.html
ublished Online July 31, 2008
Submitted on June 19, 2008
Accepted on July 18, 2008
In Situ Formation of an Oxygen-Evolving Catalyst in Neutral Water Containing Phosphate and Co2+
1 Department of Chemistry, 6-335, Massachusetts Institute of Technology, Cambridge, MA 02139–4307, USA.
* To whom correspondence should be addressed.
Daniel G. Nocera , E-mail: email@example.com