ELECTROCHEMISTRY

Silver's salty twist on water splitting

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Science  20 Mar 2015:
Vol. 347, Issue 6228, pp. 1326
DOI: 10.1126/science.347.6228.1326-a

When plants split water during photosynthesis, they expel oxygen as a by-product. Ironically, it's this oxygen-generating step that's also proving the most difficult to optimize in artificial photosynthetic schemes, where the practical goal is simply to release the oxygen while accumulating hydrogen for fuel. Du et al. explore an alternative scheme, whereby the electrons to make the hydrogen come from chloride ions—already abundant in seawater—instead of other water molecules. Specifically, they show that dissolved silver ions act as efficient electrocatalysts for chloride oxidation, provided that the chloride is present at a high enough concentration to form (AgCl2) and (AgCl3)2− ions, both of which are more soluble and more reactive than AgCl.

J. Am. Chem. Soc. 10.1021/jacs.5b00037 (2015).

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