There is a small constellation of atoms – 4 manganese, 5 oxygens and one calcium – that lies embedded in a protein matrix in what is known as Photosystem II (PSII). This is the water-splitting complex in plants: the key process in photosynthesis and one which technologists would dearly love to replicate to create solar fuels. An intense effort is revealing the secrets of this cubane structure and how it performs. A paper in the August 15th issue of Science takes the structure further: the process of water splitting has 5 stages and everything up to an including stage 4 is now revealed. As the journal’s commentary has it, we are now one step away from the oxygen releasing step itself. In fact, of course, the important product if the process is not oxygen (although this has many industrial uses) but the other component of water: hydrogen – key to the low carbon economy.
By itself, understanding the natural process won’t enable an instant solar fix. Attempts have been made to create synthetic cubanes but the water splitting ability is a millionth of that of the natural system. PSII, like all enzymatic processes, is orders of magnitude more efficient that simple inorganic catalysis.
But that efficient ways of mimicking photosystem II will now be discovered seems inevitable. The goal is to create from air, water and sunlight liquid fuels and feedstocks such as methanol that will not only power motor vehicles (allowing all the existing infrastructure of pipelines and filling stations to remain) but allow the chemicals and plastics industries to be fed from a carbon-neutral source. In some cases these processes will even be carbon negative in taking carbon dioxide (to be reduced by solar-generated hydrogen) from power station effluent or even the air.
Watch that cubane space!
Science, 15 August 2014, pp. 736 and 804-808
By itself, understanding the natural process won’t enable an instant solar fix. Attempts have been made to create synthetic cubanes but the water splitting ability is a millionth of that of the natural system. PSII, like all enzymatic processes, is orders of magnitude more efficient that simple inorganic catalysis.
But that efficient ways of mimicking photosystem II will now be discovered seems inevitable. The goal is to create from air, water and sunlight liquid fuels and feedstocks such as methanol that will not only power motor vehicles (allowing all the existing infrastructure of pipelines and filling stations to remain) but allow the chemicals and plastics industries to be fed from a carbon-neutral source. In some cases these processes will even be carbon negative in taking carbon dioxide (to be reduced by solar-generated hydrogen) from power station effluent or even the air.
Watch that cubane space!
Science, 15 August 2014, pp. 736 and 804-808
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