H+ reduction catalyst

H2O oxidising photo catalyst

2H2O

4H+ + 4e-

Anode

Electrolyte

Cathode

→

e-

O2

→

→ 4H+ +

2H2

H+ reduction catalyst

H2O oxidising photo catalyst

2H2O

4H+ + 4e-

Anode

Electrolyte

Cathode

→ e-O2

→

→ 4H+ +

2H2

Dan Nocera (MIT) has created an O2 producing catalyst

A conventional solar panel would capture sunlight to produce electricity - in turn, that electricity would power an electrolyzer, which would use his catalyst to split water.

A conventional solar panel would capture sunlight to produce electricity - in turn, that electricity would power an electrolyzer, which would use his catalyst to split water.

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An Australian-US research team led by Monash University

has developed a catalyst for the splitting of water into oxygen and hydrogen using

solar energy.

The researchers have copied nature, taking the elements and mechanisms found in plant life that have evolved

over 3 billion years and recreated one of those processes in the laboratory.

Barber's team has located the binding sites of two chloride ions in photosystem II (PSII), the complex that catalyses the water splitting reaction in plants. The location of the ions suggests that they play a role in transport of protons and substrates into and out of the active centre, says the team.'We have used a trick whereby heavier bromide ions were substituted for chloride within PSII, which maintains full activity,' Barber says. This allowed the team to use an x-ray diffraction technique sensitive to heavy atoms to study crystals of the enzymes and locate the binding sites for bromide, and therefore chloride."Chemists can use this information to design efficient systems for solar energy conversion."- Gary Brudvig'It has been known for a long time that chloride ions play a role in the chemistry of PSII, but the molecular mechanism has been unclear,' says Gary Brudvig of Yale University, New Haven, US, who himself studies the water splitting reaction in PSII. He says that Barber's results represent 'a significant step forward,' as the exact role of the chloride ions can now be studied based on the new structural information.'Natural photosynthesis provides a working example of how sunlight can be used for fuel production,' says Brudvig. 'With a better understanding of how nature does the very difficult water-oxidation chemistry, chemists can use this information to design efficient systems for solar energy conversion'.

The second approach would employ a system that more closely mimics the structure of a leaf. The catalysts would be deployed side by side with special dye molecules designed to absorb sunlight; the energy captured by the dyes would drive the water-splitting reaction. Either way, solar energy would be converted into hydrogen fuel that could be easily stored and used at night--or whenever it's needed.

- jpg - earthyblog.com/joomla/images/62/water1.jpg

A manganese cluster is central to a plant’s ability to use water, carbon dioxide and sunlight to make carbohydrates and oxygen.

Man-made mimics of this cluster developed by Charles Dismukes some time ago

Present rearchers have taken it a step further, harnessing the ability of these molecules to convert water into its component elements, oxygen and hydrogen

The catalyst assembly was still active after three days of continuous use

While the efficiency of the system still needs to be improved, it is a major step forward in an attempt to power the vehicles of the future. In July, researchers at MIT reported on their discovery of a new water-splitting catalyst that is prepared from earth-abundant materials (cobalt and phosphorous) and operates in benign conditions: pH neutral water at room temperature and 1 atm pressure. The cobalt-phosphorous catalyst targets the generation of oxygen gas from water; another catalyst generates the hydrogen. This is really cool in case the technology transcends in to reality.

The second approach would employ a system that more closely mimics the structure of a leaf. The catalysts would be deployed side by side with special dye molecules designed to absorb sunlight; the energy captured by the dyes would drive the water-splitting reaction. Either way, solar energy would be converted into hydrogen fuel that could be easily stored and used at night--or whenever it's needed.